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updated Sat Aug 22 2020 by Robert van Engelen
 
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1 
2 C and C++ XML Data Bindings {#mainpage}
3 ===========================
4 
5 [TOC]
6 
7 Introduction {#intro}
8 ============
9 
10 This article presents a detailed overview of the gSOAP XML data bindings for C
11 and C++. The XML data bindings for C and C++ are extensively used with gSOAP
12 Web services to serialize C and C++ data in XML as part of the SOAP/XML Web
13 services payloads. Also REST XML with gSOAP relies on XML serialization of C
14 and C++ data via XML data bindings.
15 
16 The major advantage of XML data bindings is that your application data is
17 always **type safe** in C and C++ by binding XML schema types to C/C++ types.
18 So integers in XML are bound to C integers, strings in XML are bound to C or
19 C++ strings, complex types in XML are bound to C structs or C++ classes, and so
20 on. The structured data you create and accept will fit the data model and is
21 **static type safe**. In other words, by leveraging strong typing in C/C++,
22 your XML data meets **XML schema validation requirements** and satisfies **XML
23 interoperability requirements**.
24 
25 In fact, gSOAP data bindings are more powerful than simply representing C/C++
26 data in XML. The gSOAP tools implement true and tested **structure-preserving
27 serialization** of C/C++ data in XML, including the serialization of cyclic
28 graph structures with id-ref XML attributes. The gSOAP tools also generate
29 routines for deep copying and deep deletion of C/C++ data structures to
30 simplify memory management. In addition, C/C++ structures are deserialized
31 into managed memory, managed by the gSOAP `soap` context.
32 
33 At the end of this article two examples are given to illustrate the application
34 of XML data bindings. The first simple example <i>`address.cpp`</i> shows how to use
35 wsdl2h to bind an XML schema to C++. The C++ application reads and writes an
36 XML file into and from a C++ "address book" data structure as a simple example.
37 The C++ data structure is an STL vector of address objects. The second example
38 <i>`graph.cpp`</i> shows how C++ data can be accurately serialized as a tree, digraph,
39 and cyclic graph in XML. The digraph and cyclic graph serialization rules
40 implement SOAP 1.1/1.2 multi-ref encoding with id-ref attributes to link
41 elements through IDREF XML references, creating a an XML graph with pointers to
42 XML nodes that preserves the structural integrity of the serialized C++ data.
43 
44 These examples demonstrate XML data bindings only for relatively simple data
45 structures and types. The gSOAP tools support more than just these type of
46 structures to serialize in XML. There are practically no limits to the
47 serialization of C and C++ data types in XML.
48 
49 Also the support for XML schema (XSD) components is unlimited. The wsdl2h tool
50 maps schemas to C and C++ using built-in intuitive mapping rules, while
51 allowing the mappings to be customized using a <i>`typemap.dat`</i> file with mapping
52 instructions for wsdl2h.
53 
54 The information in this article is applicable to gSOAP 2.8.26 and greater that
55 support C++11 features. However, C++11 is not required. The material and the
56 examples in this article use plain C and C++, until the point where we
57 introduce C++11 smart pointers and scoped enumerations. While most of the
58 examples in this article are given in C++, the concepts also apply to C with
59 the exception of containers, smart pointers, classes and their methods. None
60 of these exceptions limit the use of the gSOAP tools for C in any way.
61 
62 The data binding concepts described in this article were first envisioned in
63 1999 by Prof. Robert van Engelen at the Florida State University. An
64 implementation was created in 2000, named "stub/skeleton compiler". The first
65 articles on its successor version "gSOAP" appeared in 2002. The principle of
66 mapping XSD components to C/C++ types and vice versa is now widely adopted in
67 systems and programming languages, including Java web services and by C# WCF.
68 
69 We continue to be committed to our goal to empower C/C++ developers with
70 powerful autocoding tools for XML. Our commitment started in the very early
71 days of SOAP by actively participating in
72 [SOAP interoperability testing](http://www.whitemesa.com/interop.htm),
73 participating in the development and testing of the
74 [W3C XML Schema Patterns for Databinding Interoperability](http://www.w3.org/2002/ws/databinding),
75 and continues by contributing to the development of
76 [OASIS open standards](https://www.oasis-open.org) in partnership with leading
77 IT companies in the world.
78 
79 🔝 [Back to table of contents](#)
80 
81 Notational Conventions {#conventions}
82 ======================
83 
84 The typographical conventions used by this document are:
85 
86 * `Courier` denotes C and C++ source code.
87 
88 * <i>`Courier`</i> denotes XML content, JSON content, file and path names, and URIs.
89 
90 * <b>`Courier`</b> denotes HTTP content, text file content, and shell commands with command line options and arguments.
91 
92 The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD",
93 "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to
94 be interpreted as described in RFC-2119.
95 
96 🔝 [Back to table of contents](#)
97 
98 Mapping WSDL and XML schemas to C/C++ {#tocpp}
99 =====================================
100 
101 To convert WSDL and XML schemas (XSD files) to code, we use the wsdl2h command
102 on the command line (or command prompt), after opening a terminal. The wsdl2h
103 command generates the data binding interface code that is saved to a special
104 Web services and data bindings interface header file with extension <i>`.h`</i>
105 that contains the WSDL service declarations and the data binding interface
106 declarations in a familiar C/C++ format:
107 
108  wsdl2h [options] -o file.h ... XSD and WSDL files ...
109 
110 This command converts WSDL and XSD files to C++ (or pure C with
111 <b>`wsdl2h -c`</b>) and saves the data binding interface to a interface header
112 file <i>`file.h`</i> that uses familiar C/C++ syntax extended with `//gsoap`
113 [directives](#directives) and annotations. Notational conventions are used in
114 the data binding interface to declare serializable C/C++ types and functions
115 for Web service operations.
116 
117 The WSDL 1.1/2.0, SOAP 1.1/1.2, and XSD 1.0/1.1 standards are supported by the
118 gSOAP tools. In addition, the most popular WS specifications are also
119 supported, including WS-Addressing, WS-ReliableMessaging, WS-Discovery,
120 WS-Security, WS-Policy, WS-SecurityPolicy, and WS-SecureConversation.
121 
122 This article focusses mainly on XML data bindings. XML data bindings for C/C++
123 bind XML schema types to C/C++ types. So integers in XML are bound to C
124 integers, strings in XML are bound to C or C++ strings, complex types in XML
125 are bound to C structs or C++ classes, and so on.
126 
127 A data binding is dual, meaning supporting a two way direction for development.
128 Either you start with WSDLs and/or XML schemas that are mapped to equivalent
129 C/C++ types, or you start with C/C++ types that are mapped to XSD types.
130 Either way, the end result is that you can serialize C/C++ types in XML such
131 that your XML is an instance of XML schema(s) and is validated against these
132 schema(s).
133 
134 This covers all of the following standard XSD components with their optional
135 attributes and properties:
136 
137 XSD component | attributes and properties
138 -------------- | -------------------------
139 schema | targetNamespace, version, elementFormDefault, attributeFormDefault, defaultAttributes
140 attribute | name, ref, type, use, default, fixed, form, targetNamespace, wsdl:arrayType
141 element | name, ref, type, default, fixed, form, nillable, abstract, substitutionGroup, minOccurs, maxOccurs, targetNamespace
142 simpleType | name
143 complexType | name, abstract, mixed, defaultAttributesApply
144 all | *n/a*
145 choice | minOccurs, maxOccurs
146 sequence | minOccurs, maxOccurs
147 group | name, ref, minOccurs, maxOccurs
148 attributeGroup | name, ref
149 any | minOccurs, maxOccurs
150 anyAttribute | *n/a*
151 
152 And also the following standard XSD directives are covered:
153 
154 directive | description
155 ---------- | -----------
156 import | Imports a schema into the importing schema for referencing
157 include | Include schema component definitions into a schema
158 override | Override by replacing schema component definitions
159 redefine | Extend or restrict schema component definitions
160 annotation | Annotates a component
161 
162 The XSD facets and their mappings to C/C++ are:
163 
164 XSD facet | maps to
165 -------------- | -------
166 enumeration | `enum`
167 simpleContent | class/struct wrapper with `__item` member
168 complexContent | class/struct
169 list | `enum*` bitmask (`enum*` enumerates a bitmask up to 64 bits)
170 extension | class/struct inheritance/extension
171 restriction | `typedef` and class/struct inheritance/redeclaration
172 length | `typedef` with restricted content length annotation
173 minLength | `typedef` with restricted content length annotation
174 maxLength | `typedef` with restricted content length annotation
175 minInclusive | `typedef` with numerical value range restriction annotation
176 maxInclusive | `typedef` with numerical value range restriction annotation
177 minExclusive | `typedef` with numerical value range restriction annotation
178 maxExclusive | `typedef` with numerical value range restriction annotation
179 precision | `typedef` with pattern annotation (pattern used for output, but input is not validated)
180 scale | `typedef` with pattern annotation (pattern used for output, but input is not validated)
181 totalDigits | `typedef` with pattern annotation (pattern used for output, but input is not validated)
182 fractionDigits | `typedef` with pattern annotation (pattern used for output, but input is not validated)
183 pattern | `typedef` with pattern annotation (define `soap::fsvalidate` callback to validate patterns)
184 union | string with union of value
185 
186 All primitive XSD types are supported, including but not limited to the
187 following XSD types:
188 
189 XSD type | maps to
190 ---------------- | -------
191 any/anyType | `_XML` string with literal XML content (or enable DOM with wsdl2h option `-d`)
192 anyURI | string (i.e. `char*`, `wchar_t*`, `std::string`, `std::wstring`)
193 string | string (i.e. `char*`, `wchar_t*`, `std::string`, `std::wstring`)
194 boolean | `bool` (C++) or `enum xsd__boolean` (C)
195 byte | `char` (i.e. `int8_t`)
196 short | `short` (i.e. `int16_t`)
197 int | `int` (i.e. `int32_t`)
198 long | `LONG64` (i.e. `long long` and `int64_t`)
199 unsignedByte | `unsigned char` (i.e. `uint8_t`)
200 unsignedShort | `unsigned short` (i.e. `uint16_t`)
201 unsignedInt | `unsigned int` (i.e. `uint32_t`)
202 unsignedLong | `ULONG64` (i.e. `unsigned long long` and `uint64_t`)
203 float | `float`
204 double | `double`
205 integer | string or `#import "custom/int128.h"` to use 128 bit `xsd__integer`
206 decimal | string or `#import "custom/long_double.h"` to use `long double`
207 precisionDecimal | string
208 duration | string or `#import "custom/duration.h"` to use 64 bit `xsd__duration`
209 dateTime | `time_t` or `#import "custom/struct_tm.h"` to use `struct tm` for `xsd__dateTime`
210 time | string or `#import "custom/long_time.h"` to use 64 bit `xsd__time`
211 date | string or `#import "custom/struct_tm_date.h"` to use `struct tm` for `xsd__date`
212 hexBinary | special class/struct `xsd__hexBinary`
213 base64Binary | special class/struct `xsd__base64Binary`
214 QName | `_QName` string (URI normalization rules are applied)
215 
216 All other primitive XSD types not listed above are mapped to strings, by
217 wsdl2h generating a `typedef` to string for these types. For example,
218 <i>`xsd:token`</i> is bound to a C++ or C string:
219 
220 ~~~{.cpp}
221  typedef std::string xsd__token; // C++
222  typedef char *xsd__token; // C (wsdl2h option -c)
223 ~~~
224 
225 This associates a compatible value space to the type with the appropriate XSD
226 type name used by the soapcpp2-generated serializers.
227 
228 It is possible to remap types by adding the appropriate mapping rules to
229 <i>`typemap.dat`</i> as we will explain in more detail in the next section.
230 
231 Imported custom serializers are intended to extend the C/C++ type bindings when
232 the default binding to string is not satisfactory to your taste and if the
233 target platform supports these C/C++ types. To add custom serializers to
234 <i>`typemap.dat`</i> for wsdl2h, see [adding custom serializers](#custom) below.
235 
236 🔝 [Back to table of contents](#)
237 
238 Using typemap.dat to customize data bindings {#typemap}
239 ============================================
240 
241 Use a <i>`typemap.dat`</i> file to redefine namespace prefixes and to customize type
242 bindings for the the generated header files produced by the wsdl2h tool. The
243 <i>`typemap.dat`</i> is the default file processed by wsdl2h. Use <b>`wsdl2h -tfile.dat`</b>
244 option <b>`-tfile.dat`</b> to specify a different mapping file <i>`file.dat`</i>.
245 
246 Declarations in <i>`typemap.dat`</i> can be broken up over multiple lines by
247 continuing on the next line by ending each line to be continued with a
248 backslash <b>`\`</b>. The limit is 4095 characters per line, whether the line is
249 broken up or not.
250 
251 🔝 [Back to table of contents](#)
252 
253 XML namespace bindings {#typemap1}
254 ----------------------
255 
256 The wsdl2h tool generates C/C++ type declarations that use `ns1`, `ns2`, etc.
257 as schema-binding URI prefixes. These default prefixes are generated somewhat
258 arbitrarily for each schema targetNamespace URI, meaning that their ordering
259 may change depending on the WSDL and XSD order of processing with wsdl2h.
260 
261 Therefore, it is **strongly recommended** to declare your own prefix for each
262 schema URI in <i>`typemap.dat`</i> to reduce maintaince effort of your code. This
263 is more robust when anticipating possible changes of the schema(s) and/or the
264 binding URI(s) and/or the tooling algorithms.
265 
266 The first and foremost important thing to do is to define prefix-URI bindings
267 for our C/C++ code by adding the following line(s) to our <i>`typemap.dat`</i> or make
268 a copy of this file and add the line(s) that bind our choice of prefix name to
269 each URI:
270 
271  prefix = "URI"
272 
273 For example, to use `g` as a prefix for the "urn:graph" XML namespace:
274 
275  g = "urn:graph"
276 
277 This produces `g__name` C/C++ type names that are bound to the "urn:graph"
278 schema by association of `g` to the generated C/C++ types.
279 
280 This means that <i>`<g:name xmlns:g="urn:graph">`</i> is parsed as an instance of a
281 `g__name` C/C++ type. Also <i>`<x:name xmlns:x="urn:graph">`</i> parses as an
282 instance of `g__name`, because the prefix <i>`x`</i> has the same URI value
283 <i>`urn:graph`</i>. Prefixes in XML have local scopes (like variables in a block).
284 
285 The first run of wsdl2h will reveal the XML namespace URIs, so you do not need
286 to search WSDLs and XSD files for all of the target namespaces. Just copy them
287 from the generated header file after the first run into <i>`typemap.dat`</i> for
288 editing.
289 
290 @note Only define a namespace prefix once in <i>`typemap.dat`</i>. That is, do not
291 use the same prefix for multiple XML namespace URIs. This is to avoid
292 namespace conflicts that may cause failed builds and failures in XML parsing
293 and XML schema validation.
294 
295 🔝 [Back to table of contents](#)
296 
297 XSD type bindings {#typemap2}
298 -----------------
299 
300 Custom C/C++ type bindings can be declared in <i>`typemap.dat`</i> to associate C/C++
301 types with specific schema types. These type bindings have four parts:
302 
303  prefix__type = declaration | use | ptruse
304 
305 where
306 
307 - <b>`prefix__type`</b> is the schema type to be customized (the <b>`prefix__type`</b> name
308  uses the common double underscore naming convention);
309 
310 - <b>`declaration`</b> declares the C/C++ type in the wsdl2h-generated header file.
311  This part can be empty if no explicit declaration is needed;
312 
313 - <b>`use`</b> is an optional part that specifies how the C/C++ type is used in the
314  code. When omitted, it is the same as <b>`prefix__type`</b>;
315 
316 - <b>`ptruse`</b> is an optional part that specifies how the type is used as a pointer
317  type. By default it is the <b>`use`</b> type name with a <b>`*`</b> or C++11
318  <b>`std::shared_ptr<type>`</b> when enabled (see further below). If <b>`use`</b> is already a
319  pointer type by the presence of a <b>`*`</b> in the <b>`use`</b> part, then the default
320  <b>`ptruse`</b> type is the same as the <b>`use`</b> type (that is, no double
321  pointers <b>`**`</b> will be created in this case).
322 
323 For example, to map <i>`xsd:duration`</i> to a `long long` (`LONG64`) type that holds
324 millisecond duration values, we can use the custom serializer declared in
325 <i>`gsoap/custom/duration.h`</i> by adding the following line to <i>`typemap.dat`</i>:
326 
327  xsd__duration = #import "custom/duration.h"
328 
329 Here, we omitted the second and third parts, because `xsd__duration` is the
330 name that wsdl2h uses for this type in our generated code so we should leave
331 the <b>`use`</b> part unspecified. The third part is omitted to let wsdl2h use
332 `xsd__duration *` for pointers or `std::shared_ptr<xsd__duration>` if smart
333 pointers are enabled.
334 
335 To map <i>`xsd:string`</i> to `wchar_t*` wide strings for C source code output:
336 
337  xsd__string = | wchar_t* | wchar_t*
338 
339 For C++ we can use the `std::wstring` wide string:
340 
341  xsd__string = | std::wstring
342 
343 Note that the first part is empty, because these types do not require a
344 declaration. A <b>`ptruse`</b> part is also defined for `wchar_t*`, but this
345 is actually needed because the wsdl2h tool recognizes that the <b>`use`</b>
346 part `wchar_t*` is already a pointer. By contrast, when using 8-bit strings,
347 it is recommended to use the `SOAP_C_UTFSTRING` flag to enable UTF-8 formatted
348 strings.
349 
350 When the auto-generated declaration should be preserved but the <b>`use`</b> or
351 <b>`ptruse`</b> parts replaced, then we use an ellipsis for the declaration part:
352 
353  prefix__type = ... | use | ptruse
354 
355 This is useful to map schema polymorphic types to C types for example, where we
356 need to be able to both handle a base type and its extensions as per schema
357 extensibility. Say we have a base type called <i>`ns:base`</i> that is extended, then
358 we can remap this to a C type that permits referening the extended types via a
359 `void*` as follows:
360 
361  ns__base = ... | int __type_base; void*
362 
363 such that `__type_base` and `void*` will be used to (de)serialize any data
364 type, including base and its derived types. The `__type_base` integer is set
365 to a `SOAP_TYPE_T` value to indicate what type of data the `void*` pointer
366 points to.
367 
368 🔝 [Back to table of contents](#)
369 
370 Custom serializers for XSD types {#custom}
371 --------------------------------
372 
373 In the previous part we saw how a custom serializer is used to bind
374 <i>`xsd:duration`</i> to a `long long` (`LONG64` or `int64_t`) type to store millisecond
375 duration values:
376 
377  xsd__duration = #import "custom/duration.h"
378 
379 The `xsd__duration` type is an alias of `long long` (`LONG64` or `int64_t`).
380 
381 While wsdl2h will use this binding declared in <i>`typemap.dat`</i>
382 automatically, you will also need to compile <i>`gsoap/custom/duration.c`</i>.
383 Each custom serializer has an interface header file to be imported into another
384 interface header file that declares the custom type for soapcpp2 and a
385 serializer implementation file written in C, which should be compiled with the
386 application. You can compile these in C++ (rename files to <i>`.cpp`</i> if
387 needed).
388 
389 A custom serializer is declared in an interface header file for soapcpp2 using
390 `extern typedef`. The typedef name declared is serializable, whereas the
391 type on which it is based is not serializable. This declaration can be
392 combined with `volatile` when the type should not be redeclared, see
393 [volatile classes and structs](#toxsd9-2). For example, the custom serializer
394 for `struct tm` is the type `xsd__datetime` declared as follows in
395 `gsoap/custom/struct_tm.h`:
396 
397 ~~~{.cpp}
398  extern typedef volatile struct tm
399  {
400  int tm_sec; ///< seconds (0 - 60)
401  int tm_min; ///< minutes (0 - 59)
402  int tm_hour; ///< hours (0 - 23)
403  int tm_mday; ///< day of month (1 - 31)
404  int tm_mon; ///< month of year (0 - 11)
405  int tm_year; ///< year - 1900
406  int tm_wday; ///< day of week (Sunday = 0) (NOT USED)
407  int tm_yday; ///< day of year (0 - 365) (NOT USED)
408  int tm_isdst; ///< is summer time in effect?
409  char* tm_zone; ///< abbreviation of timezone (NOT USED)
410  } xsd__dateTime;
411 ~~~
412 
413 Another example is `xsd__duration` as a custom serializer for the C++11 type
414 `std::chrono::nanoseconds`:
415 
416 ~~~{.cpp}
417  extern typedef class std::chrono::nanoseconds xsd__duration;
418 ~~~
419 
420 Next, we present all pre-defined custom serializers that are available to you.
421 
422 🔝 [Back to table of contents](#)
423 
424 ### xsd:integer {#custom-1}
425 
426 The wsdl2h tool maps <i>`xsd:integer`</i> to a string by default. To map <i>`xsd:integer`</i> to
427 the 128 bit big int type `__int128_t`:
428 
429  xsd__integer = #import "custom/int128.h"
430 
431 The `xsd__integer` type is an alias of `__int128_t`.
432 
433 @warning Beware that the <i>`xsd:integer`</i> value space of integers is in principle
434 unbounded and values can be of arbitrary length. A value range fault
435 `SOAP_TYPE` (value exceeds native representation) or `SOAP_LENGTH` (value
436 exceeds range bounds) will be thrown by the deserializer if the value is out of
437 range.
438 
439 Other XSD integer types that are restrictions of <i>`xsd:integer`</i>, are
440 <i>`xsd:nonNegativeInteger`</i> and <i>`xsd:nonPositiveInteger`</i>, which are further restricted
441 by <i>`xsd:positiveInteger`</i> and <i>`xsd:negativeInteger`</i>. To bind these types to
442 `__int128_t` add the following definitions to <i>`typemap.dat`</i>:
443 
444  xsd__nonNegativeInteger = typedef xsd__integer xsd__nonNegativeInteger 0 : ;
445  xsd__nonPositiveInteger = typedef xsd__integer xsd__nonPositiveInteger : 0 ;
446  xsd__positiveInteger = typedef xsd__integer xsd__positiveInteger 1 : ;
447  xsd__negativeInteger = typedef xsd__integer xsd__negativeInteger : -1 ;
448 
449 Or simply uncomment these definitions in <i>`typemap.dat`</i> when you are using the
450 latest gSOAP releases.
451 
452 @note If `__int128_t` 128 bit integers are not supported on your platform and if it
453 is certain that <i>`xsd:integer`</i> values are within 64 bit value bounds for your
454 application's use, then you can map this type to `LONG64`:
455 
456  xsd__integer = typedef LONG64 xsd__integer;
457 
458 @note Again, a value range fault `SOAP_TYPE` or `SOAP_LENGTH` will be thrown by
459 the deserializer if the value is out of range.
460 
461 After running wsdl2h and soapcpp2, compile <i>`gsoap/custom/int128.c`</i> with your project.
462 
463 @see Section [numerical types](#toxsd5).
464 
465 🔝 [Back to table of contents](#)
466 
467 ### xsd:decimal {#custom-2}
468 
469 The wsdl2h tool maps <i>`xsd:decimal`</i> to a string by default. To map <i>`xsd:decimal`</i> to
470 extended precision floating point:
471 
472  xsd__decimal = #import "custom/long_double.h" | long double
473 
474 By contrast to all other custom serializers, this serializer enables `long
475 double` natively without requiring a new binding name (`xsd__decimal` is NOT
476 defined).
477 
478 If your system supports <i>`quadmath.h`</i> quadruple precision floating point
479 `__float128`, you can map <i>`xsd:decimal`</i> to `xsd__decimal` that is an alias of
480 `__float128`:
481 
482  xsd__decimal = #import "custom/float128.h"
483 
484 @warning Beware that <i>`xsd:decimal`</i> is in principle a decimal value with arbitraty
485 lengths. A value range fault `SOAP_TYPE` will be thrown by the deserializer if
486 the value is out of range.
487 
488 In the XML payload the special values <i>`INF`</i>, <i>`-INF`</i>, <i>`NaN`</i>
489 represent plus or minus infinity and not-a-number, respectively.
490 
491 After running wsdl2h and soapcpp2, compile <i>`gsoap/custom/long_double.c`</i> with your
492 project.
493 
494 @see Section [numerical types](#toxsd5).
495 
496 🔝 [Back to table of contents](#)
497 
498 ### xsd:dateTime {#custom-3}
499 
500 The wsdl2h tool maps <i>`xsd:dateTime`</i> to `time_t` by default.
501 
502 The trouble with `time_t` when represented as 32 bit `long` integers is that it
503 is limited to dates between 1970 and 2038. A 64 bit `time_t` is safe to use if
504 the target platform supports it, but lack of 64 bit `time_t` portability may
505 still cause date range issues.
506 
507 For this reason `struct tm` should be used to represent wider date ranges. This
508 custom serializer avoids using date and time information in `time_t`. You get
509 the raw date and time information. You only lose the day of the week
510 information. It is always Sunday (`tm_wday=0`).
511 
512 To map <i>`xsd:dateTime`</i> to `xsd__dateTime` which is an alias of `struct tm`:
513 
514  xsd__dateTime = #import "custom/struct_tm.h"
515 
516 If the limited date range of `time_t` is not a problem but you want to increase
517 the time precision with fractional seconds, then we suggest to map <i>`xsd:dateTime`</i>
518 to `struct timeval`:
519 
520  xsd__dateTime = #import "custom/struct_timeval.h"
521 
522 If the limited date range of `time_t` is not a problem but you want to use the
523 C++11 time point type `std::chrono::system_clock::time_point` (which internally
524 uses `time_t`):
525 
526  xsd__dateTime = #import "custom/chrono_time_point.h"
527 
528 Again, we should make sure that the dates will not exceed the date range when
529 using the default `time_t` binding for <i>`xsd:dateTime`</i> or when binding
530 <i>`xsd:dateTime`</i> to `struct timeval` or to `std::chrono::system_clock::time_point`.
531 These are safe to use in applications that use <i>`xsd:dateTime`</i> to record date
532 stamps within a given window. Otherwise, we recommend the `struct tm` custom
533 serializer.
534 
535 After running wsdl2h and soapcpp2, compile <i>`gsoap/custom/struct_tm.c`</i> with your
536 project.
537 
538 You could even map <i>`xsd:dateTime`</i> to a plain string (use `char*` with C and
539 `std::string` with C++). For example:
540 
541  xsd__dateTime = | char*
542 
543 @see Section [date and time types](#toxsd7).
544 
545 🔝 [Back to table of contents](#)
546 
547 ### xsd:date {#custom-4}
548 
549 The wsdl2h tool maps <i>`xsd:date`</i> to a string by default. We can map <i>`xsd:date`</i> to
550 `struct tm`:
551 
552  xsd__date = #import "custom/struct_tm_date.h"
553 
554 The `xsd__date` type is an alias of `struct tm`. The serializer ignores the
555 time part and the deserializer only populates the date part of the struct,
556 setting the time to 00:00:00. There is no unreasonable limit on the date range
557 because the year field is stored as an integer (`int`).
558 
559 After running wsdl2h and soapcpp2, compile <i>`gsoap/custom/struct_tm_date.c`</i> with your
560 project.
561 
562 @see Section [date and time types](#toxsd7).
563 
564 🔝 [Back to table of contents](#)
565 
566 ### xsd:time {#custom-5}
567 
568 The wsdl2h tool maps <i>`xsd:time`</i> to a string by default. We can map <i>`xsd:time`</i> to
569 an `unsigned long long` (`ULONG64` or `uint64_t`) integer with microsecond time
570 precision:
571 
572  xsd__time = #import "custom/long_time.h"
573 
574 This type represents 00:00:00.000000 to 23:59:59.999999, from `0` to an upper
575 bound of `86399999999`. A microsecond resolution means that a 1 second
576 increment requires an increment of 1000000 in the integer value. The serializer
577 adds a UTC time zone.
578 
579 After running wsdl2h and soapcpp2, compile <i>`gsoap/custom/long_time.c`</i> with your
580 project.
581 
582 @see Section [date and time types](#toxsd7).
583 
584 🔝 [Back to table of contents](#)
585 
586 ### xsd:duration {#custom-6}
587 
588 The wsdl2h tool maps <i>`xsd:duration`</i> to a string by default, unless <i>`xsd:duration`</i>
589 is mapped to a `long long` (`LONG64` or `int64_t`) type with with millisecond
590 (ms) time duration precision:
591 
592  xsd__duration = #import "custom/duration.h"
593 
594 The `xsd__duration` type is a 64 bit signed integer that can represent
595 106,751,991,167 days forwards (positive) and backwards (negative) in time in
596 increments of 1 ms (1/1000 of a second).
597 
598 Rescaling of the duration value by may be needed when adding the duration value
599 to a `time_t` value, because `time_t` may or may not have a seconds resolution,
600 depending on the platform and possible changes to `time_t`.
601 
602 Rescaling is done automatically when you add a C++11 `std::chrono::nanoseconds`
603 value to a `std::chrono::system_clock::time_point` value. To use
604 `std::chrono::nanoseconds` as <i>`xsd:duration`</i>:
605 
606  xsd__duration = #import "custom/chrono_duration.h"
607 
608 This type can represent 384,307,168 days (2^63 nanoseconds) forwards and
609 backwards in time in increments of 1 ns (1/1,000,000,000 of a second).
610 
611 Certain observations with respect to receiving durations in years and months
612 apply to both of these serializer decoders for <i>`xsd:duration`</i>.
613 
614 After running wsdl2h and soapcpp2, compile <i>`gsoap/custom/duration.c`</i> with your
615 project.
616 
617 @see Section [time duration types](#toxsd8).
618 
619 🔝 [Back to table of contents](#)
620 
621 Custom Qt serializers for XSD types {#qt}
622 -----------------------------------
623 
624 The gSOAP distribution includes several custom serializers for Qt types. Also
625 Qt container classes are supported, see
626 [the built-in typemap.dat variables $CONTAINER, $POINTER and $SIZE](#typemap5).
627 
628 This feature requires gSOAP 2.8.34 or higher and Qt 4.8 or higher.
629 
630 Each Qt custom serializer has an interface header file for soapcpp2 and a C++
631 implementation file to be compiled with your project.
632 
633 Other Qt primitive types that are Qt `typedef`s of C/C++ types do not require a
634 custom serializer.
635 
636 🔝 [Back to table of contents](#)
637 
638 ### xsd:string {#qt-1}
639 
640 To use Qt strings instead of C++ strings, add the following definition to
641 <i>`typemap.dat`</i>:
642 
643  xsd__string = #import "custom/qstring.h"
644 
645 After running wsdl2h and soapcpp2, compile <i>`gsoap/custom/qstring.cpp`</i> with your
646 project.
647 
648 🔝 [Back to table of contents](#)
649 
650 ### xsd:base64Binary {#qt-2}
651 
652 To use Qt byte arrays for <i>`xsd:base64Binary`</i> instead of the
653 `xsd__base64Binary` class, add the following definition to <i>`typemap.dat`</i>:
654 
655  xsd__base64Binary = #import "custom/qbytearray_base64.h"
656 
657 After running wsdl2h and soapcpp2, compile <i>`gsoap/custom/qbytearray_base64.cpp`</i> with
658 your project.
659 
660 🔝 [Back to table of contents](#)
661 
662 ### xsd:hexBinary {#qt-3}
663 
664 To use Qt byte arrays for <i>`xsd:hexBinary`</i> instead of the `xsd__base64Binary`
665 class, add the following definition to <i>`typemap.dat`</i>:
666 
667  xsd__hexBinary = #import "custom/qbytearray_hex.h"
668 
669 After running wsdl2h and soapcpp2, compile <i>`gsoap/custom/qbytearray_hex.cpp`</i> with
670 your project.
671 
672 🔝 [Back to table of contents](#)
673 
674 ### xsd:dateTime {#qt-4}
675 
676 To use Qt QDateTime for <i>`xsd:dateTime`</i>, add the following definition to
677 <i>`typemap.dat`</i>:
678 
679  xsd__dateTime = #import "custom/datetime.h"
680 
681 After running wsdl2h and soapcpp2, compile <i>`gsoap/custom/qdatetime.cpp`</i> with
682 your project.
683 
684 🔝 [Back to table of contents](#)
685 
686 ### xsd:date {#qt-5}
687 
688 To use Qt QDate for <i>`xsd:date`</i>, add the following definition to
689 <i>`typemap.dat`</i>:
690 
691  xsd__date = #import "custom/qdate.h"
692 
693 After running wsdl2h and soapcpp2, compile <i>`gsoap/custom/qdate.cpp`</i> with your
694 project.
695 
696 🔝 [Back to table of contents](#)
697 
698 ### xsd:time {#qt-6}
699 
700 To use Qt QDate for <i>`xsd:time`</i>, add the following definition to
701 <i>`typemap.dat`</i>:
702 
703  xsd__time = #import "custom/qtime.h"
704 
705 After running wsdl2h and soapcpp2, compile <i>`gsoap/custom/qtime.cpp`</i> with your
706 project.
707 
708 🔝 [Back to table of contents](#)
709 
710 Class/struct member additions {#typemap3}
711 -----------------------------
712 
713 All generated classes and structs can be augmented with additional
714 members such as methods, constructors and destructors, and private members:
715 
716  prefix__type = $ member-declaration
717 
718 For example, we can add method declarations and private members to a class, say
719 `ns__record` as follows:
720 
721  ns__record = $ ns__record(const ns__record &); // copy constructor
722  ns__record = $ void print(); // a print method
723  ns__record = $ private: int status; // a private member
724 
725 Method declarations cannot include any code, because soapcpp2's input permits
726 only type declarations, not code.
727 
728 🔝 [Back to table of contents](#)
729 
730 Replacing XSD types by equivalent alternatives {#typemap4}
731 ----------------------------------------------
732 
733 Type replacements can be given to replace one type entirely with another given
734 type:
735 
736  prefix__type1 == prefix__type2
737 
738 This replaces all `prefix__type1` by `prefix__type2` in the wsdl2h output.
739 
740 @warning Do not agressively replace types, because this can cause XML schema
741 validation to fail when a value-type mismatch is encountered in the XML input.
742 Therefore, only replace similar types with other similar types that are wider
743 (e.g. `short` by `int` and `float` by `double`).
744 
745 🔝 [Back to table of contents](#)
746 
747 The built-in typemap.dat variables $CONTAINER, $POINTER and $SIZE {#typemap5}
748 -----------------------------------------------------------------
749 
750 The <i>`typemap.dat`</i> <b>`$CONTAINER`</b> variable defines the container type to use in
751 the wsdl2h-generated declarations for C++, which is `std::vector` by default.
752 For example, to use `std::list` as the container in the wsdl2h-generated
753 declarations we add the following line to <i>`typemap.dat`</i>:
754 
755  $CONTAINER = std::list
756 
757 Also a Qt container can be used instead of the default `std::vector`, for
758 example `QVector`:
759 
760  [
761  #include <QVector>
762  ]
763  $CONTAINER = QVector
764 
765 To remove containers, use <b>`wsdl2h -s`</b>. This also removes `std::string`,
766 but you can re-introduce `std::string` with
767 <b>`xsd__string = | std::string`</b> in <i>`typemap.dat`</i>.
768 
769 The <i>`typemap.dat`</i> <b>`$POINTER`</b> variable defines the smart pointer to use in the
770 wsdl2h-generated declarations for C++, which replaces the use of `*` pointers.
771 For example:
772 
773  $POINTER = std::shared_ptr
774 
775 Not all pointers in the generated output are replaced by smart pointers by
776 wsdl2h, such as pointers as union members and pointers as struct/class members
777 that point to arrays of values.
778 
779 @note The standard smart pointer `std::shared_ptr` is generally safe to use.
780 Other smart pointers such as `std::unique_ptr` and `std::auto_ptr` may cause
781 compile-time errors when classes have smart pointer members but no copy
782 constructor (a default copy constructor). A copy constructor is required for
783 non-shared smart pointer copying or swapping.
784 
785 Alternatives to `std::shared_ptr` of the form `NAMESPACE::shared_ptr` can be
786 assigned to <b>`$POINTER`</b> when the namespace `NAMESPACE` also implements
787 `NAMESPACE::make_shared` and when the shared pointer class provides `reset()`
788 and`get()` methods and the dereference operator. For example Boost
789 `boost::shared_ptr`:
790 
791  [
792  #include <boost/shared_ptr.hpp>
793  ]
794  $POINTER = boost::shared_ptr
795 
796 The user-defined content between <b>`[`</b> and <b>`]`</b> ensures that we include the Boost
797 header files that are needed to support `boost::shared_ptr` and
798 `boost::make_shared`.
799 
800 The variable <b>`$SIZE`</b> defines the type of array sizes, which is `int` by
801 default. For example, to change array size types to `size_t`:
802 
803  $SIZE = size_t
804 
805 Permissible types are `int` and `size_t`. This variable does not affect the
806 size of dynamic arrays, `xsd__hexBinary` and `xsd__base64Binary` types, which
807 is always `int`.
808 
809 🔝 [Back to table of contents](#)
810 
811 User-defined content {#typemap6}
812 --------------------
813 
814 Any other content to be generated by wsdl2h can be included in <i>`typemap.dat`</i> by
815 enclosing it within brackets <b>`[`</b> and <b>`]`</b> anywhere in the <i>`typemap.dat`</i> file.
816 Each of the two brackets must appear at the start of a new line.
817 
818 For example, we can add an `#import "wsa5.h"` to the wsdl2h-generated output as
819 follows:
820 
821  [
822  #import "import/wsa5.h"
823  ]
824 
825 which emits the `#import "import/wsa5.h"` literally at the start of the
826 wsdl2h-generated header file.
827 
828 🔝 [Back to table of contents](#)
829 
830 Mapping C/C++ to XML schema {#toxsd}
831 ===========================
832 
833 The soapcpp2 command generates the data binding implementation code from a data
834 binding interface <i>`file.h`</i>:
835 
836  soapcpp2 [options] file.h
837 
838 where <i>`file.h`</i> is a interface header file that declares the XML data
839 binding interface. The <i>`file.h`</i> is typically generated by wsdl2h, but
840 you can also declare one yourself. If so, add `//gsoap`
841 [directives](#directives) and declare in this file all our C/C++ types you want
842 to serialize in XML.
843 
844 You can also declare functions that will be converted to Web service operations
845 by soapcpp2. Global function declarations define service operations, which are
846 of the form:
847 
848 ~~~{.cpp}
849  int prefix__func(arg1, arg2, ..., argn, result);
850 ~~~
851 
852 where `arg1`, `arg2`, ..., `argn` are formal argument declarations of the input
853 and `result` is a formal argument for the output, which must be a pointer or
854 reference to the result object to be populated. More information on declaring
855 and implementing service operation functions can be found in the
856 [gSOAP user guide.](../../guide/html/index.html)
857 
858 🔝 [Back to table of contents](#)
859 
860 Overview of serializable C/C++ types {#toxsd1}
861 ------------------------------------
862 
863 The following C/C++ types are supported by soapcpp2 and mapped to XSD types
864 and constructs. See the subsections below for more details or follow the links.
865 
866 🔝 [Back to table of contents](#)
867 
868 ### List of Boolean types
869 
870 Boolean Type | Notes
871 ----------------------------- | -----
872 `bool` | C++ bool
873 `enum xsd__boolean` | C alternative to C++ `bool` with `false_` and `true_`
874 
875 @see Section [C++ bool and C alternative](#toxsd3).
876 
877 🔝 [Back to table of contents](#)
878 
879 ### List of enumeration and bitmask types
880 
881 Enumeration Type | Notes
882 ----------------------------- | -----
883 `enum` | enumeration
884 `enum class` | C++11 scoped enumeration, requires `soapcpp2 -c++11`
885 `enum*` | a bitmask that enumerates values 1, 2, 4, 8, ...
886 `enum* class` | C++11 scoped enumeration bitmask, requires `soapcpp2 -c++11`
887 
888 @see Section [enumerations and bitmasks](#toxsd4).
889 
890 🔝 [Back to table of contents](#)
891 
892 ### List of numerical types
893 
894 Numerical Type | Notes
895 ----------------------------- | -----
896 `char` | byte
897 `short` | 16 bit integer
898 `int` | 32 bit integer
899 `long` | 32 bit integer
900 `LONG64` | 64 bit integer
901 `xsd__integer` | 128 bit integer, use `#import "custom/int128.h"`
902 `long long` | same as `LONG64`
903 `unsigned char` | unsigned byte
904 `unsigned short` | unsigned 16 bit integer
905 `unsigned int` | unsigned 32 bit integer
906 `unsigned long` | unsigned 32 bit integer
907 `ULONG64` | unsigned 64 bit integer
908 `unsigned long long` | same as `ULONG64`
909 `int8_t` | same as `char`
910 `int16_t` | same as `short`
911 `int32_t` | same as `int`
912 `int64_t` | same as `LONG64`
913 `uint8_t` | same as `unsigned char`
914 `uint16_t` | same as `unsigned short`
915 `uint32_t` | same as `unsigned int`
916 `uint64_t` | same as `ULONG64`
917 `size_t` | transient type (not serializable)
918 `float` | 32 bit float
919 `double` | 64 bit float
920 `long double` | extended precision float, use `#import "custom/long_double.h"`
921 `xsd__decimal` | `quadmath.h` library 128 bit quadruple precision float, use `#import "custom/float128.h"`
922 `typedef` | declares a type name, with optional value range and string length bounds
923 
924 @see Section [numerical types](#toxsd5).
925 
926 🔝 [Back to table of contents](#)
927 
928 ### List of string types
929 
930 String Type | Notes
931 ----------------------------- | -----
932 `char*` | string (may contain UTF-8 with flag `SOAP_C_UTFSTRING`)
933 `wchar_t*` | wide string
934 `std::string` | C++ string (may contain UTF-8 with flag `SOAP_C_UTFSTRING`)
935 `std::wstring` | C++ wide string
936 `char[N]` | fixed-size string, requires `soapcpp2 -b`
937 `_QName` | normalized QName content
938 `_XML` | literal XML string content with wide characters in UTF-8
939 `typedef` | declares a new string type name, may restrict string length
940 
941 @see Section [string types](#toxsd6).
942 
943 🔝 [Back to table of contents](#)
944 
945 ### List of date and time types
946 
947 Date and Time Type | Notes
948 --------------------------------------- | -----
949 `time_t` | date and time point since epoch
950 `struct tm` | date and time point, use `#import "custom/struct_tm.h"`
951 `struct tm` | date point, use `#import "custom/struct_tm_date.h"`
952 `struct timeval` | date and time point, use `#import "custom/struct_timeval.h"`
953 `unsigned long long` | time point in microseconds, use `#import "custom/long_time.h"`
954 `std::chrono::system_clock::time_point` | date and time point, use `#import "custom/chrono_time_point.h"`
955 
956 @see Section [date and time types](#toxsd7).
957 
958 🔝 [Back to table of contents](#)
959 
960 ### List of time duration types
961 
962 Time Duration Type | Notes
963 ----------------------------- | -----
964 `long long` | duration in milliseconds, use `#import "custom/duration.h"`
965 `std::chrono::nanoseconds` | duration in nanoseconds, use `#import "custom/chrono_duration.h"`
966 
967 @see Section [time duration types](#toxsd8).
968 
969 🔝 [Back to table of contents](#)
970 
971 ### List of classes, structs, unions, pointers, containers, and arrays
972 
973 Classes, Structs, and Members | Notes
974 ----------------------------- | -----
975 `class` | C++ class with single inheritance only
976 `struct` | C struct or C++ struct without inheritance
977 `std::shared_ptr<T>` | C++11 smart shared pointer
978 `std::unique_ptr<T>` | C++11 smart pointer
979 `std::auto_ptr<T>` | C++ smart pointer
980 `std::deque<T>` | use `#import "import/stldeque.h"`
981 `std::list<T>` | use `#import "import/stllist.h"`
982 `std::vector<T>` | use `#import "import/stlvector.h"`
983 `std::set<T>` | use `#import "import/stlset.h"`
984 `template<T> class` | a container with `begin()`, `end()`, `size()`, `clear()`, and `insert()` methods
985 `T*` | pointer to data of type `T`
986 `T*` | as a class or struct member: points to data of type `T` or array of `T` with member `__size`
987 `T[N]` | as a class or struct member: fixed-size array of type `T`
988 `union` | as a class or struct member: requires a variant selector member `__union`
989 `void*` | as a class or struct member: requires a `__type` member to indicate the type of object pointed to
990 
991 @see Section [classes and structs](#toxsd9).
992 
993 🔝 [Back to table of contents](#)
994 
995 ### List of special classes and structs
996 
997 Special Classes and Structs | Notes
998 ----------------------------- | -----
999 Special Array class/struct | single and multidimensional SOAP Arrays
1000 Special Wrapper class/struct | complexTypes with simpleContent, wraps `__item` member
1001 `xsd__hexBinary` | binary content
1002 `xsd__base64Binary` | binary content and optional DIME/MIME/MTOM attachments
1003 `xsd__anyType` | DOM elements, use `#import "dom.h"`
1004 `@xsd__anyAttribute` | DOM attributes, use `#import "dom.h"`
1005 
1006 @see Section [special classes and structs](#toxsd10).
1007 
1008 🔝 [Back to table of contents](#)
1009 
1010 Colon notation versus name prefixing with XML tag name translation {#toxsd2}
1011 ------------------------------------------------------------------
1012 
1013 To bind C/C++ type names to XSD types, a simple form of name prefixing is used
1014 by the gSOAP tools by prepending the XML namespace prefix to the C/C++ type
1015 name with a pair of undescrores. This also ensures that name clashes cannot
1016 occur when multiple WSDL and XSD files are converted to C/C++. Also, C++
1017 namespaces are not sufficiently rich to capture XML schema namespaces
1018 accurately, for example when class members are associated with schema elements
1019 defined in another XML namespace and thus the XML namespace scope of the
1020 member's name is relevant, not just its type.
1021 
1022 However, from a C/C++ centric point of view this can be cumbersome. Therefore,
1023 colon notation is an alternative to physically augmenting C/C++ names with
1024 prefixes.
1025 
1026 For example, the following class uses colon notation to bind the `record` class
1027 to the <i>`urn:types`</i> schema:
1028 
1029 ~~~{.cpp}
1030  //gsoap ns schema namespace: urn:types
1031  class ns:record // binding 'ns:' to a type name
1032  {
1033  public:
1034  std::string name;
1035  uint64_t SSN;
1036  ns:record *spouse; // using 'ns:' with the type name
1037  ns:record(); // using 'ns:' here too
1038  ~ns:record(); // and here
1039  };
1040 ~~~
1041 
1042 The colon notation is stripped away by soapcpp2 when generating the data
1043 binding implementation code for our project. So the final code just uses
1044 `record` to identify this class and its constructor/destructor.
1045 
1046 When using colon notation make sure to be consistent and not use colon notation
1047 mixed with prefixed forms. The qualified name `ns:record` differs from `ns__record`,
1048 because `ns:record` is compiled to an unqualified `record` name in the source
1049 code output by the soapcpp2 tool.
1050 
1051 Colon notation also facilitates overruling the elementFormDefault and
1052 attributeFormDefault declaration that is applied to local elements and
1053 attributes, when declared as members of classes, structs, and unions. For more
1054 details, see [qualified and unqualified members](#toxsd9-6).
1055 
1056 A C/C++ identifier name (a type name, member name, function name, or parameter
1057 name) is translated to an XML tag name by the following rules:
1058 
1059 - Two leading underscores indicates that the identifier name has no XML tag
1060  name, i.e. this name is not visible in XML and is not translated.
1061 
1062 - A leading underscore is removed, but the underscore indicates that: **a**) a
1063  struct/class member name or parameter name has a wildcard XML tag name (i.e.
1064  matches any XML tag), or **b**) a type name that has a
1065  [document root element definition](#toxsd9-7).
1066 
1067 - Trailing underscores are removed (i.e. trailing underscores can be used to
1068  avoid name clashes with keywords).
1069 
1070 - Underscores within names are translated to hyphens (hyphens are more common
1071  in XML tag names).
1072 
1073 - `_USCORE` is translated to an underscore in the translated XML tag name.
1074 
1075 - `_DOT` is translated to a dot (<i>`.`</i>) in the translated XML tag name.
1076 
1077 - `_xHHHH` is translated to the Unicode character with code point HHHH (hex).
1078 
1079 - C++11 Unicode identifier name characters in UTF-8 are translated as-is.
1080 
1081 For example, the C/C++ namespace qualified identifier name `s_a__my_way` is
1082 translated to the XML tag name <i>`s-a:my-way`</i> by translating the prefix `s_a`
1083 and the local name `my_way`.
1084 
1085 Struct/class member and parameter name translation can be overruled by using
1086 [backtick XML tags](#toxsd9-5-1) (with gSOAP 2.8.30 and greater).
1087 
1088 🔝 [Back to table of contents](#)
1089 
1090 C++ bool and C alternative {#toxsd3}
1091 --------------------------
1092 
1093 The C++ `bool` type is bound to built-in XSD type <i>`xsd:boolean`</i>.
1094 
1095 The C alternative is to define an enumeration:
1096 
1097 ~~~{.cpp}
1098  enum xsd__boolean { false_, true_ };
1099 ~~~
1100 
1101 or by defining an enumeration in C with pseudo-scoped enumeration constants:
1102 
1103 ~~~{.cpp}
1104  enum xsd__boolean { xsd__boolean__false, xsd__boolean__true };
1105 ~~~
1106 
1107 The XML value space of these types is <i>`false`</i> and <i>`true`</i>, but also accepted
1108 are <i>`0`</i> and <i>`1`</i> values for <i>`false`</i> and <i>`true`</i>, respectively.
1109 
1110 To prevent name clashes, `false_` and `true_` have a trailing underscore in
1111 their `enum` symbols. Trailing underscores are removed from the XML value space.
1112 
1113 🔝 [Back to table of contents](#)
1114 
1115 Enumerations and bitmasks {#toxsd4}
1116 -------------------------
1117 
1118 Enumerations are mapped to XSD simpleType enumeration restrictions of
1119 <i>`xsd:string`</i>, <i>`xsd:QName`</i>, and <i>`xsd:long`</i>.
1120 
1121 Consider for example:
1122 
1123 ~~~{.cpp}
1124  enum ns__Color { RED, WHITE, BLUE };
1125 ~~~
1126 
1127 which maps to a simpleType restriction of <i>`xsd:string`</i> in the soapcpp2-generated
1128 schema:
1129 
1130 <div class="alt">
1131 ~~~{.xml}
1132  <simpleType name="Color">
1133  <restriction base="xsd:string">
1134  <enumeration value="RED"/>
1135  <enumeration value="WHITE"/>
1136  <enumeration value="BLUE"/>
1137  </restriction>
1138  </simpleType>
1139 ~~~
1140 </div>
1141 
1142 Enumeration name constants can be pseudo-scoped to prevent name clashes,
1143 because enumeration name constants have a global scope in C and C++:
1144 
1145 ~~~{.cpp}
1146  enum ns__Color { ns__Color__RED, ns__Color__WHITE, ns__Color__BLUE };
1147 ~~~
1148 
1149 You can also use C++11 scoped enumerations to prevent name clashes:
1150 
1151 ~~~{.cpp}
1152  enum class ns__Color : int { RED, WHITE, BLUE };
1153 ~~~
1154 
1155 Here, the enumeration class base type `: int` is optional. In place of `int`
1156 in the example above, we can also use `int8_t`, `int16_t`, `int32_t`, or
1157 `int64_t`.
1158 
1159 The XML value space of the enumertions defined above is <i>`RED`</i>, <i>`WHITE`</i>, and
1160 <i>`BLUE`</i>.
1161 
1162 Prefix-qualified enumeration name constants are mapped to simpleType
1163 restrictions of <i>`xsd:QName`</i>, for example:
1164 
1165 ~~~{.cpp}
1166  enum ns__types { xsd__int, xsd__float };
1167 ~~~
1168 
1169 which maps to a simpleType restriction of <i>`xsd:QName`</i> in the soapcpp2-generated
1170 schema:
1171 
1172 <div class="alt">
1173 ~~~{.xml}
1174  <simpleType name="types">
1175  <restriction base="xsd:QName">
1176  <enumeration value="xsd:int"/>
1177  <enumeration value="xsd:float"/>
1178  </restriction>
1179  </simpleType>
1180 ~~~
1181 </div>
1182 
1183 Enumeration name constants can be pseudo-numeric as follows:
1184 
1185 ~~~{.cpp}
1186  enum ns__Primes { _3 = 3, _5 = 5, _7 = 7, _11 = 11 };
1187 ~~~
1188 
1189 which maps to a simpleType restriction of <i>`xsd:long`</i>:
1190 
1191 <div class="alt">
1192 ~~~{.xml}
1193  <simpleType name="Color">
1194  <restriction base="xsd:long">
1195  <enumeration value="3"/>
1196  <enumeration value="5"/>
1197  <enumeration value="7"/>
1198  <enumeration value="11"/>
1199  </restriction>
1200  </simpleType>
1201 ~~~
1202 </div>
1203 
1204 The XML value space of this type is <i>`3`</i>, <i>`5`</i>, <i>`7`</i>, and <i>`11`</i>.
1205 
1206 Besides (pseudo-) scoped enumerations, another way to prevent name clashes
1207 accross enumerations is to start an enumeration name constant with one
1208 underscore or followed it by any number of underscores, which makes it
1209 unique. The leading and trailing underscores are removed from the XML value
1210 space.
1211 
1212 ~~~{.cpp}
1213  enum ns__ABC { A, B, C };
1214  enum ns__BA { B, A }; // BAD: B = 1 but B is already defined as 2
1215  enum ns__BA_ { B_, A_ }; // OK
1216 ~~~
1217 
1218 The gSOAP soapcpp2 tool permits reusing enumeration name constants across
1219 (non-scoped) enumerations as long as these values are assigned the same
1220 constant. Therefore, the following is permitted:
1221 
1222 ~~~{.cpp}
1223  enum ns__Primes { _3 = 3, _5 = 5, _7 = 7, _11 = 11 };
1224  enum ns__Throws { _1 = 1, _2 = 2, _3 = 3, _4 = 4, _5 = 5, _6 = 6 };
1225 ~~~
1226 
1227 A bitmask type is an `enum*` "product enumeration" with a geometric,
1228 power-of-two sequence of values assigned to the enumeration constants:
1229 
1230 ~~~{.cpp}
1231  enum* ns__Options { SSL3, TLS10, TLS11, TLS12, TLS13 };
1232 ~~~
1233 
1234 where the product enum assigns 1 to `SSL3`, 2 to `TLS10`, 4 to `TLS11`, 8
1235 to `TLS12`, and 16 to `TLS13`, which allows these enumeration constants to be
1236 used in composing bitmasks with `|` (bitwise or) `&` (bitwise and), and `~`
1237 (bitwise not):
1238 
1239 ~~~{.cpp}
1240  enum ns__Options options = (enum ns__Options)(SSL3 | TLS10 | TLS11 | TLS12 | TLS13);
1241  if (options & SSL3) // if SSL3 is an option, warn and remove from options
1242  {
1243  warning();
1244  options &= ~SSL3;
1245  }
1246 ~~~
1247 
1248 The bitmask type maps to a simpleType list restriction of <i>`xsd:string`</i> in the
1249 soapcpp2-generated XML schema:
1250 
1251 <div class="alt">
1252 ~~~{.xml}
1253  <simpleType name="Options">
1254  <list>
1255  <restriction base="xsd:string">
1256  <enumeration value="SSL3"/>
1257  <enumeration value="TLS10"/>
1258  <enumeration value="TLS11"/>
1259  <enumeration value="TLS12"/>
1260  <enumeration value="TLS13"/>
1261  </restriction>
1262  </list>
1263  </simpleType>
1264 ~~~
1265 </div>
1266 
1267 The XML value space of this type consists of all 16 possible subsets of the
1268 four values, represented by an XML string with space-separated values. For
1269 example, the bitmask `TLS10 | TLS11 | TLS12` equals 14 and is represented by
1270 the XML text <i>`TLS10 TLS11 TLS12`</i>.
1271 
1272 You can also use C++11 scoped enumerations with bitmasks using `enum*` product
1273 enumerations:
1274 
1275 ~~~{.cpp}
1276  enum* class ns__Options { SSL3, TLS10, TLS11, TLS12, TLS13 };
1277 ~~~
1278 
1279 The base type of a scoped enumeration bitmask, when explicitly given, is
1280 ignored. The base type is either `int` or `int64_t`, depending on the number
1281 of constants enumerated in the bitmask.
1282 
1283 To convert `enum` name constants and bitmasks to a string, we use the
1284 auto-generated function for enum `T`:
1285 
1286 ~~~{.cpp}
1287  const char *soap_T2s(struct soap*, enum T val)
1288 ~~~
1289 
1290 The string returned is stored in an internal buffer of the current `soap`
1291 context, so you should copy it to keep it from being overwritten. For example,
1292 use `char *soap_strdup(struct soap*, const char*)`.
1293 
1294 To convert a string to an `enum` constant or bitmask, we use the auto-generated
1295 function
1296 
1297 ~~~{.cpp}
1298  int soap_s2T(struct soap*, const char *str, enum T *val)
1299 ~~~
1300 
1301 This function takes the name (or names, space-separated for bitmasks) of
1302 the enumeration constant in a string `str`. Names should be given without the
1303 pseudo-scope prefix and without trailing underscores. The function sets `val`
1304 to the corresponding integer enum constant or to a bitmask. The function
1305 returns `SOAP_OK` (zero) on success or an error if the string is not a valid
1306 enumeration name.
1307 
1308 🔝 [Back to table of contents](#)
1309 
1310 Numerical types {#toxsd5}
1311 ---------------
1312 
1313 Integer and floating point types are mapped to the equivalent built-in XSD
1314 types with the same sign and bit width.
1315 
1316 The `size_t` type is transient (not serializable) because its width is platform
1317 dependent. We recommend to use `uint64_t` instead.
1318 
1319 The XML value space of integer types are their decimal representations without
1320 loss of precision.
1321 
1322 The XML value space of floating point types are their decimal representations.
1323 The decimal representations are formatted with the printf format string `"%.9G"`
1324 for floats and the printf format string `"%.17lG"` for double. To change the
1325 format strings, we can assign new strings to the following `soap` context
1326 members:
1327 
1328 ~~~{.cpp}
1329  soap.float_format = "%g";
1330  soap.double_format = "%lg";
1331  soap.long_double_format = "%Lg";
1332 ~~~
1333 
1334 Decimal representations may result in a loss of precision of the least
1335 significant decimal. Therefore, the format strings that are used by default
1336 are sufficiently precise to avoid loss, but this may result in long decimal
1337 fractions in the XML value space.
1338 
1339 The `long double` extended floating point type requires a custom serializer:
1340 
1341 ~~~{.cpp}
1342  #import "custom/long_double.h"
1343  ... // use long double
1344 ~~~
1345 
1346 You can now use `long double`, which has a serializer that serializes this type
1347 as <i>`xsd:decimal`</i>. Compile and link your code with the file
1348 <i>`gsoap/custom/long_double.c`</i>.
1349 
1350 The value space of floating point values includes the special values
1351 <i>`INF`</i>, <i>`-INF`</i>, and <i>`NaN`</i>. You can check a value for plus
1352 or minus infinity and not-a-number as follows:
1353 
1354 ~~~{.cpp}
1355  soap_isinf(x) && x > 0 // is x INF?
1356  soap_isinf(x) && x < 0 // is x -INF?
1357  soap_isnan(x) // is x NaN?
1358 ~~~
1359 
1360 To assign these values, use:
1361 
1362 ~~~{.cpp}
1363  // x is float // x is double, long double, or __float128
1364  x = FLT_PINFY; x = DBL_PINFTY;
1365  x = FLT_NINFY; x = DBL_NINFTY;
1366  x = FLT_NAN; x = DBL_NAN;
1367 ~~~
1368 
1369 If your system supports `__float128` then you can also use this 128 bit
1370 floating point type with a custom serializer:
1371 
1372 ~~~{.cpp}
1373  #import "custom/float128.h"
1374  ... // use xsd__decimal
1375 ~~~
1376 
1377 Then use the `xsd__decimal` alias of `__float128`, which has a serializer. Do
1378 not use `__float128` directly, which is transient (not serializable).
1379 
1380 To check for <i>`INF`</i>, <i>`-INF`</i>, and <i>`NaN`</i> of a `__float128`
1381 value use:
1382 
1383 ~~~{.cpp}
1384  isinfq(x) && x > 0 // is x INF?
1385  isinfq(x) && x < 0 // is x -INF?
1386  isnanq(x) // is x NaN?
1387 ~~~
1388 
1389 The range of a `typedef`-defined numerical type can be restricted using the range
1390 `:` operator with inclusive lower and upper bounds. For example:
1391 
1392 ~~~{.cpp}
1393  typedef int ns__narrow -10 : 10;
1394 ~~~
1395 
1396 This maps to a simpleType restriction of <i>`xsd:int`</i> in the soapcpp2-generated
1397 schema:
1398 
1399 <div class="alt">
1400 ~~~{.xml}
1401  <simpleType name="narrow">
1402  <restriction base="xsd:int">
1403  <minInclusive value="-10"/>
1404  <maxInclusive value="10"/>
1405  </restriction>
1406  </simpleType>
1407 ~~~
1408 </div>
1409 
1410 The lower and upper bound of a range are optional. When omitted, values are
1411 not bound from below or from above, respectively.
1412 
1413 The range of a floating point `typedef`-defined type can be restricted within
1414 floating point constant bounds.
1415 
1416 Also with a floating point `typedef` a `printf`-format pattern can be given of the
1417 form `"%[width][.precision]f"` to format decimal values using the given width
1418 and precision fields:
1419 
1420 ~~~{.cpp}
1421  typedef float ns__PH "%5.2f" 0.0 : 14.0;
1422 ~~~
1423 
1424 This maps to a simpleType restriction of <i>`xsd:float`</i> in the soapcpp2-generated
1425 schema:
1426 
1427 <div class="alt">
1428 ~~~{.xml}
1429  <simpleType name="PH">
1430  <restriction base="xsd:float">
1431  <totalDigits value="5"/>
1432  <fractionDigits value="2"/>
1433  <minInclusive value="0"/>
1434  <maxInclusive value="14"/>
1435  </restriction>
1436  </simpleType>
1437 ~~~
1438 </div>
1439 
1440 For exclusive bounds, we use the `<` operator instead of the `:` range
1441 operator:
1442 
1443 ~~~{.cpp}
1444  typedef float ns__epsilon 0.0 < 1.0;
1445 ~~~
1446 
1447 Values `eps` of `ns__epsilon` are restricted between `0.0 < eps < 1.0`.
1448 
1449 This maps to a simpleType restriction of <i>`xsd:float`</i> in the soapcpp2-generated
1450 schema:
1451 
1452 <div class="alt">
1453 ~~~{.xml}
1454  <simpleType name="epsilon">
1455  <restriction base="xsd:float">
1456  <minExclusive value="0"/>
1457  <maxExclusive value="1"/>
1458  </restriction>
1459  </simpleType>
1460 ~~~
1461 </div>
1462 
1463 To make just one of the bounds exclusive, while keeping the other bound
1464 inclusive, we add a `<` on the left or on the right side of the range ':'
1465 operator. For example:
1466 
1467 ~~~{.cpp}
1468  typedef float ns__pos 0.0 < : ; // 0.0 < pos
1469  typedef float ns__neg : < 0.0 ; // neg < 0.0
1470 ~~~
1471 
1472 It is valid to make both left and right side exclusive with `< : <` which is in
1473 fact identical to the exlusive range `<` operator:
1474 
1475 ~~~{.cpp}
1476  typedef float ns__epsilon 0.0 < : < 1.0; // 0.0 < eps < 1.0
1477 ~~~
1478 
1479 It helps to think of the `:` as a placeholder of the value between the two
1480 bounds, which is easier to memorize than the shorthand forms of bounds from
1481 which the `:` is removed:
1482 
1483 | bounds | validation check | shorthand |
1484 | ------------ | ---------------- | ----------- |
1485 | `1 : ` | 1 <= x | `1 ` |
1486 | `1 : 10 ` | 1 <= x <= 10 | |
1487 | ` : 10 ` | x <= 10 | |
1488 | `1 < : < 10` | 1 < x < 10 | `1 < 10 ` |
1489 | `1 : < 10` | 1 <= x < 10 | |
1490 | ` : < 10` | x < 10 | ` < 10 ` |
1491 | `1 < : ` | 1 < x | `1 < ` |
1492 | `1 < : 10 ` | 1 < x <= 10 | |
1493 
1494 Besides `float`, also `double` and `long double` values can be restricted. For
1495 example, consider a nonzero probability extended floating point precision type:
1496 
1497 ~~~{.cpp}
1498  #import "custom/long_double.h"
1499  typedef long double ns__probability "%16Lg" 0.0 < : 1.0;
1500 ~~~
1501 
1502 Value range restrictions are validated by the parser for all inbound XML data.
1503 A type fault `SOAP_TYPE` will be thrown by the deserializer if the value is out
1504 of range.
1505 
1506 Finally, if your system supports `__int128_t` then you can also use this 128
1507 bit integer type with a custom serializer:
1508 
1509 ~~~{.cpp}
1510  #import "custom/int128.h"
1511  ... // use xsd__integer
1512 ~~~
1513 
1514 Use the `xsd__integer` alias of `__int128_t`, which has a serializer. Do not
1515 use `__int128_t` directly, which is transient (not serializable).
1516 
1517 To convert numeric values to a string, we use the auto-generated function for
1518 numeric type `T`:
1519 
1520 ~~~{.cpp}
1521  const char *soap_T2s(struct soap*, T val)
1522 ~~~
1523 
1524 For numeric types `T`, the string returned is stored in an internal buffer of
1525 the current `soap` context, so you should copy it to keep it from being
1526 overwritten. For example, use `char *soap_strdup(struct soap*, const char*)`.
1527 
1528 To convert a string to a numeric value, we use the auto-generated function
1529 
1530 ~~~{.cpp}
1531  int soap_s2T(struct soap*, const char *str, T *val)
1532 ~~~
1533 
1534 where `T` is for example `int`, `LONG64`, `float`, `decimal` (the custom
1535 serializer name of `long double`) or `xsd__integer` (the custom serializer name
1536 of `__int128_t`). The function `soap_s2T` returns `SOAP_OK` on success or an
1537 error when the value is not numeric. For floating point types, `"INF"`, `"-INF"`
1538 and `"NaN"` are valid strings to convert to numbers.
1539 
1540 🔝 [Back to table of contents](#)
1541 
1542 String types {#toxsd6}
1543 ------------
1544 
1545 String types are mapped to the built-in <i>`xsd:string`</i> and <i>`xsd:QName`</i> XSD types.
1546 
1547 The wide strings `wchar_t*` and `std::wstring` may contain Unicode that is
1548 preserved in the XML value space.
1549 
1550 Strings `char*` and `std::string` can only contain extended Latin, but we can
1551 store UTF-8 content that is preserved in the XML value space when the `soap`
1552 context is initialized with the flag `SOAP_C_UTFSTRING`.
1553 
1554 @warning Beware that many XML 1.0 parsers reject all control characters (those
1555 between `#x1` and `#x1F`) except for `#x9`, `#xA`, and `#xD`. With the
1556 newer XML 1.1 version parsers (including gSOAP) you should be fine.
1557 
1558 The length of a string of a `typedef`-defined string type can be restricted:
1559 
1560 ~~~{.cpp}
1561  typedef std::string ns__password 6 : 16;
1562 ~~~
1563 
1564 which maps to a simpleType restriction of <i>`xsd:string`</i> in the soapcpp2-generated
1565 schema:
1566 
1567 <div class="alt">
1568 ~~~{.xml}
1569  <simpleType name="password">
1570  <restriction base="xsd:string">
1571  <minLength value="6"/>
1572  <maxLength value="16"/>
1573  </restriction>
1574  </simpleType>
1575 ~~~
1576 </div>
1577 
1578 String length restrictions are validated by the parser for inbound XML data.
1579 A value length fault `SOAP_LENGTH` will be thrown by the deserializer if the
1580 string is too long or too short.
1581 
1582 In addition, an XSD regex pattern restriction can be associated with a string
1583 typedef:
1584 
1585 ~~~{.cpp}
1586  typedef std::string ns__password "([a-zA-Z]|[0-9]|-)+" 6 : 16;
1587 ~~~
1588 
1589 which maps to a simpleType restriction of <i>`xsd:string`</i> in the soapcpp2-generated
1590 schema:
1591 
1592 <div class="alt">
1593 ~~~{.xml}
1594  <simpleType name="password">
1595  <restriction base="xsd:string">
1596  <pattern value="([a-zA-Z0-9]|-)+"/>
1597  <minLength value="6"/>
1598  <maxLength value="16"/>
1599  </restriction>
1600  </simpleType>
1601 ~~~
1602 </div>
1603 
1604 Pattern restrictions are validated by the parser for inbound XML data only if
1605 the `soap::fsvalidate` and `soap::fwvalidate` callbacks are defined.
1606 
1607 Exclusive length bounds can be used with strings:
1608 
1609 ~~~{.cpp}
1610  typedef std::string ns__string255 : < 256; // same as 0 : 255
1611 ~~~
1612 
1613 Fixed-size strings (`char[N]`) are rare occurrences in the wild, but apparently
1614 still used in some projects to store strings. To facilitate fixed-size string
1615 serialization, use <b>`soapcpp2 -b`</b> option <b>`-b`</b>. For example:
1616 
1617 ~~~{.cpp}
1618  typedef char ns__buffer[10]; // requires soapcpp2 option -b
1619 ~~~
1620 
1621 which maps to a simpleType restriction of <i>`xsd:string`</i> in the soapcpp2-generated
1622 schema:
1623 
1624 <div class="alt">
1625 ~~~{.xml}
1626  <simpleType name="buffer">
1627  <restriction base="xsd:string">
1628  <maxLength value="9"/>
1629  </restriction>
1630  </simpleType>
1631 ~~~
1632 </div>
1633 
1634 Fixed-size strings must contain NUL-terminated text and should not contain raw
1635 binary data. Also, the length limitation is more restrictive for UTF-8 content
1636 (enabled with the `SOAP_C_UTFSTRING`) that requires multibyte character
1637 encodings. As a consequence, UTF-8 content may be truncated to fit.
1638 
1639 Raw binary data can be stored in a `xsd__base64Binary` or `xsd__hexBinary`
1640 structure, or transmitted as a MIME attachment.
1641 
1642 The built-in `_QName` type is a regular C string type (`char*`) that maps to
1643 <i>`xsd:QName`</i> but has the added advantage that it holds normalized qualified names.
1644 There are actually two forms of normalized QName content, to ensure any QName
1645 is represented accurately:
1646 
1647 ~~~{.cpp}
1648  "prefix:name"
1649  "\"URI\":name"
1650 ~~~
1651 
1652 The first form of string is used when the prefix (and the binding URI) is
1653 defined in the namespace table and is bound to a URI (see the .nsmap file).
1654 The second form is used when the URI is not defined in the namespace table and
1655 therefore no prefix is available to bind and normalize the URI to.
1656 
1657 A `_QName` string may contain a sequence of space-separated QName values, not
1658 just one, and all QName values are normalized to the format shown above.
1659 
1660 To define a `std::string` base type for <i>`xsd:QName`</i>, we use a `typedef`:
1661 
1662 ~~~{.cpp}
1663  typedef std::string xsd__QName;
1664 ~~~
1665 
1666 The `xsd__QName` string content is normalized, just as with the `_QName`
1667 normalization.
1668 
1669 To serialize strings that contain literal XML content to be reproduced in the
1670 XML value space, use the built-in `_XML` string type, which is a regular C
1671 string type (`char*`) that maps to plain XML CDATA.
1672 
1673 To define a `std::string` base type for literal XML content, use a `typedef`:
1674 
1675 ~~~{.cpp}
1676  typedef std::string XML;
1677 ~~~
1678 
1679 Strings can hold any of the values of the XSD built-in primitive types. We can
1680 use a string `typedef` to declare the use of the string type as a XSD built-in
1681 type:
1682 
1683 ~~~{.cpp}
1684  typedef std::string xsd__token;
1685 ~~~
1686 
1687 You must ensure that the string values we populate in this type conform to the
1688 XML standard, which in case of <i>`xsd:token`</i> is the lexical and value spaces of
1689 <i>`xsd:token`</i> are the sets of all strings after whitespace replacement of any
1690 occurrence of `#x9`, `#xA` , and `#xD` by `#x20` and collapsing.
1691 
1692 As of version 2.8.49, the gSOAP parser will automatically collapse or replace
1693 the white space content when receiving data for XSD types that require white
1694 space collapsed or replaced. This normalization is applied to strings
1695 directly. The decision to collapse or replace is based on the `typedef` name
1696 corresponding to the built-in string-based XSD type.
1697 
1698 To copy `char*` or `wchar_t*` strings with a context that manages the allocated
1699 memory, use functions
1700 
1701 ~~~{.cpp}
1702  char *soap_strdup(struct soap*, const char*)
1703  wchar_t *soap_wstrdup(struct soap*, const wchar_t*)
1704 ~~~
1705 
1706 To convert a wide string to a UTF-8 encoded string, use function
1707 
1708 ~~~{.cpp}
1709  const char* SOAP_FMAC2 soap_wchar2s(struct soap*, const wchar_t *s)
1710 ~~~
1711 
1712 The function allocates and returns a string, with its memory being managed by
1713 the context.
1714 
1715 To convert a UTF-8 encoded string to a wide string, use function
1716 
1717 ~~~{.cpp}
1718  int soap_s2wchar(struct soap*, const char *from, wchar_t **to, long minlen, long maxlen)
1719 ~~~
1720 
1721 where `to` is set to point to an allocated `wchar_t*` string. Pass `-1` for
1722 `minlen` and `maxlen` to ignore length constraints on the target string. The
1723 function returns `SOAP_OK` or an error when the length constraints are not met.
1724 
1725 🔝 [Back to table of contents](#)
1726 
1727 Date and time types {#toxsd7}
1728 -------------------
1729 
1730 The C/C++ `time_t` type is mapped to the built-in <i>`xsd:dateTime`</i> XSD type that
1731 represents a date and time within a time zone (typically UTC).
1732 
1733 The XML value space contains ISO 8601 Gregorian time instances of the form
1734 <i>`[-]CCYY-MM-DDThh:mm:ss.sss[Z|(+|-)hh:mm]`</i>, where <i>`Z`</i> is the UTC time zone
1735 or a time zone offset <i>`(+|-)hh:mm]`</i> from UTC is used.
1736 
1737 A `time_t` value is considered and represented in UTC by the serializer.
1738 
1739 Because the `time_t` value range is restricted to dates after 01/01/1970 and
1740 before 2038 assuming `time_t` is a `long` 32 bit, care must be taken to ensure
1741 the range of <i>`xsd:dateTime`</i> values in XML exchanges do not exceed the `time_t`
1742 range.
1743 
1744 This restriction does not hold for `struct tm` (<i>`time.h`</i> library), which we can use
1745 to store and exchange a date and time in UTC without date range restrictions.
1746 The serializer uses the `struct tm` members directly for the XML value space of
1747 <i>`xsd:dateTime`</i>:
1748 
1749 ~~~{.cpp}
1750  struct tm
1751  {
1752  int tm_sec; // seconds (0 - 60)
1753  int tm_min; // minutes (0 - 59)
1754  int tm_hour; // hours (0 - 23)
1755  int tm_mday; // day of month (1 - 31)
1756  int tm_mon; // month of year (0 - 11)
1757  int tm_year; // year - 1900
1758  int tm_wday; // day of week (Sunday = 0) (NOT USED)
1759  int tm_yday; // day of year (0 - 365) (NOT USED)
1760  int tm_isdst; // is summer time in effect?
1761  char* tm_zone; // abbreviation of timezone (NOT USED)
1762  };
1763 ~~~
1764 
1765 You will lose the day of the week information. It is always Sunday
1766 (`tm_wday=0`) and the day of the year is not set either. The time zone is UTC.
1767 
1768 This `struct tm` type is mapped to the built-in <i>`xsd:dateTime`</i> XSD type and
1769 serialized with the custom serializer <i>`gsoap/custom/struct_tm.h`</i> that declares a
1770 `xsd__dateTime` type:
1771 
1772 ~~~{.cpp}
1773  #import "custom/struct_tm.h" // import typedef struct tm xsd__dateTime;
1774  ... // use xsd__dateTime
1775 ~~~
1776 
1777 Compile and link your code with <i>`gsoap/custom/struct_tm.c`</i>.
1778 
1779 The `struct timeval` (<i>`sys/time.h`</i> library) type is mapped to the
1780 built-in <i>`xsd:dateTime`</i> XSD type and serialized with the custom serializer
1781 <i>`gsoap/custom/struct_timeval.h`</i> that declares a `xsd__dateTime` type:
1782 
1783 ~~~{.cpp}
1784  #import "custom/struct_timeval.h" // import typedef struct timeval xsd__dateTime;
1785  ... // use xsd__dateTime
1786 ~~~
1787 
1788 Compile and link your code with <i>`gsoap/custom/struct_timeval.c`</i>.
1789 
1790 The same value range restrictions apply to `struct timeval` as they apply to
1791 `time_t`. The added benefit of `struct timeval` is the addition of a
1792 microsecond-precise clock:
1793 
1794 ~~~{.cpp}
1795  struct timeval
1796  {
1797  time_t tv_sec; // seconds since Jan. 1, 1970
1798  suseconds_t tv_usec; // and microseconds
1799  };
1800 ~~~
1801 
1802 A C++11 `std::chrono::system_clock::time_point` type is mapped to the built-in
1803 <i>`xsd:dateTime`</i> XSD type and serialized with the custom serializer
1804 <i>`gsoap/custom/chrono_time_point.h`</i> that declares a `xsd__dateTime` type:
1805 
1806 ~~~{.cpp}
1807  #import "custom/chrono_time_point.h" // import typedef std::chrono::system_clock::time_point xsd__dateTime;
1808  ... // use xsd__dateTime
1809 ~~~
1810 
1811 Compile and link your code with <i>`gsoap/custom/chrono_time_point.cpp`</i>.
1812 
1813 The `struct tm` type is mapped to the built-in <i>`xsd:date`</i> XSD type and serialized
1814 with the custom serializer <i>`gsoap/custom/struct_tm_date.h`</i> that declares a
1815 `xsd__date` type:
1816 
1817 ~~~{.cpp}
1818  #import "custom/struct_tm_date.h" // import typedef struct tm xsd__date;
1819  ... // use xsd__date
1820 ~~~
1821 
1822 Compile and link your code with <i>`gsoap/custom/struct_tm_date.c`</i>.
1823 
1824 The XML value space of <i>`xsd:date`</i> are Gregorian calendar dates of the form
1825 <i>`[-]CCYY-MM-DD[Z|(+|-)hh:mm]`</i> with a time zone.
1826 
1827 The serializer ignores the time part and the deserializer only populates the
1828 date part of the struct, setting the time to 00:00:00. There is no unreasonable
1829 limit on the date range because the year field is stored as an integer (`int`).
1830 
1831 An `unsigned long long` (`ULONG64` or `uint64_t`) type that contains a 24 hour
1832 time in microseconds UTC is mapped to the built-in <i>`xsd:time`</i> XSD type and
1833 serialized with the custom serializer <i>`gsoap/custom/long_time.h`</i> that declares a
1834 `xsd__time` type:
1835 
1836 ~~~{.cpp}
1837  #import "custom/long_time.h" // import typedef unsigned long long xsd__time;
1838  ... // use xsd__time
1839 ~~~
1840 
1841 Compile and link your code with <i>`gsoap/custom/long_time.c`</i>.
1842 
1843 This type represents `00:00:00.000000` to `23:59:59.999999`, from 0 to an
1844 upper bound of 86,399,999,999. A microsecond resolution means that a 1 second
1845 increment requires an increment of 1,000,000 in the integer value.
1846 
1847 The XML value space of <i>`xsd:time`</i> are points in time recurring each day of the
1848 form <i>`hh:mm:ss.sss[Z|(+|-)hh:mm]`</i>, where <i>`Z`</i> is the UTC time zone or a time
1849 zone offset from UTC is used. The `xsd__time` value is always considered and
1850 represented in UTC by the serializer.
1851 
1852 To convert date and/or time values to a string, we use the auto-generated
1853 function for type `T`:
1854 
1855 ~~~{.cpp}
1856  const char *soap_T2s(struct soap*, T val)
1857 ~~~
1858 
1859 For date and time types `T`, the string returned is stored in an internal
1860 buffer of the current `soap` context, so you should copy it to keep it from being
1861 overwritten. For example, use `char *soap_strdup(struct soap*, const char*)`.
1862 
1863 To convert a string to a date/time value, we use the auto-generated function
1864 
1865 ~~~{.cpp}
1866  int soap_s2T(struct soap*, const char *str, T *val)
1867 ~~~
1868 
1869 where `T` is for example `dateTime` (for `time_t`), `xsd__dateTime` (for
1870 `struct tm`, `struct timeval`, or `std::chrono::system_clock::time_point`).
1871 The function `soap_s2T` returns `SOAP_OK` on success or an error when the value
1872 is not a date/time.
1873 
1874 🔝 [Back to table of contents](#)
1875 
1876 Time duration types {#toxsd8}
1877 -------------------
1878 
1879 The XML value space of <i>`xsd:duration`</i> are values of the form <i>`PnYnMnDTnHnMnS`</i>
1880 where the capital letters are delimiters. Delimiters may be omitted when the
1881 corresponding member is not used.
1882 
1883 A `long long` (`LONG64` or `int64_t`) type that contains a duration (time
1884 lapse) in milliseconds is mapped to the built-in <i>`xsd:duration`</i> XSD type and
1885 serialized with the custom serializer <i>`gsoap/custom/duration.h`</i> that declares a
1886 `xsd__duration` type:
1887 
1888 ~~~{.cpp}
1889  #import "custom/duration.h" // import typedef long long xsd__duration;
1890  ... // use xsd__duration
1891 ~~~
1892 
1893 Compile and link your code with <i>`gsoap/custom/duration.c`</i>.
1894 
1895 The duration type `xsd__duration` can represent 106,751,991,167 days forward
1896 and backward with millisecond precision.
1897 
1898 Durations that exceed a month are always output in days, rather than months to
1899 avoid days-per-month conversion inacurracies.
1900 
1901 Durations that are received in years and months instead of total number of days
1902 from a reference point are not well defined, since there is no accepted
1903 reference time point (it may or may not be the current time). The decoder
1904 simple assumes that there are 30 days per month. For example, conversion of
1905 "P4M" gives 120 days. Therefore, the durations "P4M" and "P120D" are assumed
1906 to be identical, which is not necessarily true depending on the reference point
1907 in time.
1908 
1909 Rescaling of the duration value by may be needed when adding the duration value
1910 to a `time_t` value, because `time_t` may or may not have a seconds resolution,
1911 depending on the platform and possible changes to `time_t`.
1912 
1913 Rescaling is done automatically when you add a C++11 `std::chrono::nanoseconds`
1914 value to a `std::chrono::system_clock::time_point` value. To use
1915 `std::chrono::nanoseconds` as <i>`xsd:duration`</i>:
1916 
1917 ~~~{.cpp}
1918  #import "custom/chrono_duration.h" // import typedef std::chrono::duration xsd__duration;
1919  ... // use xsd__duration
1920 ~~~
1921 
1922 Compile and link your code with <i>`gsoap/custom/chrono_duration.cpp`</i>.
1923 
1924 This type can represent 384,307,168 days (2^63 nanoseconds) forwards and
1925 backwards in time in increments of 1 ns (1/1000000000 second).
1926 
1927 The same observations with respect to receiving durations in years and months
1928 apply to this serializer's decoder.
1929 
1930 To convert duration values to a string, we use the auto-generated function
1931 
1932 ~~~{.cpp}
1933  const char *soap_xsd__duration2s(struct soap*, xsd__duration val)
1934 ~~~
1935 
1936 The string returned is stored in an internal buffer, so you should copy it to
1937 keep it from being overwritten, Use `soap_strdup(struct soap*, const char*)`
1938 for example to copy this string.
1939 
1940 To convert a string to a duration value, we use the auto-generated function
1941 
1942 ~~~{.cpp}
1943  int soap_s2xsd__dateTime(struct soap*, const char *str, xsd__dateTime *val)
1944 ~~~
1945 
1946 The function returns `SOAP_OK` on success or an error when the value is not a
1947 duration.
1948 
1949 🔝 [Back to table of contents](#)
1950 
1951 Classes and structs {#toxsd9}
1952 -------------------
1953 
1954 Classes and structs are mapped to XSD complexTypes. The XML value space
1955 consists of XML elements with attributes and subelements, possibly constrained
1956 by XML schema validation rules that enforce element and attribute occurrence
1957 contraints, numerical value range constraints, and string length and pattern
1958 constraints.
1959 
1960 Classes that are declared with the gSOAP tools are limited to single
1961 inheritence only. The soapcpp2 tool does not allow structs to be inherited.
1962 
1963 The class and struct name is bound to an XML namespace by means of the prefix
1964 naming convention or by using [colon notation](#toxsd1):
1965 
1966 ~~~{.cpp}
1967  //gsoap ns schema namespace: urn:types
1968  class ns__record
1969  {
1970  public:
1971  std::string name;
1972  uint64_t SSN;
1973  ns__record *spouse;
1974  ns__record();
1975  ~ns__record();
1976  protected:
1977  struct soap *soap;
1978  };
1979 ~~~
1980 
1981 In the example above, we also added a context pointer to the `soap` context that
1982 manages this instance. It is set when the instance is created in the engine's
1983 context, for example when deserialized and populated by the engine.
1984 
1985 The class maps to a complexType in the soapcpp2-generated XML schema:
1986 
1987 <div class="alt">
1988 ~~~{.xml}
1989  <complexType name="record">
1990  <sequence>
1991  <element name="name" type="xsd:string" minOccurs="1" maxOccurs="1"/>
1992  <element name="SSN" type="xsd:unsignedLong" minOccurs="1" maxOccurs="1"/>
1993  <element name="spouse" type="ns:record" minOccurs="0" maxOccurs="1" nillable="true"/>
1994  </sequence>
1995  </complexType>
1996 ~~~
1997 </div>
1998 
1999 The following sections apply to both structs and classes. Structs require the
2000 use of the `struct` keyword with the struct name, otherwise soapcpp2 will throw
2001 a syntax error. As is often done in C, use a `typedef` to declare a `struct`
2002 that can be used without the `struct` keyword.
2003 
2004 🔝 [Back to table of contents](#)
2005 
2006 ### Serializable versus transient types and data members {#toxsd9-1}
2007 
2008 Public data members of a class or struct are serializable when their types are
2009 serializable. Private and protected members are transient and not
2010 serializable.
2011 
2012 Also `const` and `static` members are not serializable, with the exception of
2013 `const char*` and `const wchar_t*`. Types and specific class/struct members
2014 can be made transient with the `extern` qualifier for types and by marking
2015 members with `[` and `]`:
2016 
2017 ~~~{.cpp}
2018  extern class std::ostream; // declare std::ostream transient
2019  class ns__record
2020  {
2021  public:
2022  [ int num; ] // not serialized: member is marked transient with [ ]
2023  std::ostream out; // not serialized: std:ostream is transient
2024  static const int MAX = 1024; // not serialized: static const member
2025  private:
2026  std::string id; // not serialized: private member
2027  };
2028 ~~~
2029 
2030 By declaring `std::ostream` transient with `extern` you can use this type
2031 wherever you need it without soapcpp2 complaining that this class and any other
2032 class or type declared as `extern` is not defined. Do not use `extern` with
2033 `typedef`, because this declares a custom serializer, see
2034 [adding custom serializers](#custom).
2035 
2036 Marking members transient with `[` and `]` makes them transient (and visually
2037 makes them stand out). This has otherwise no effect on the generated code for
2038 the class or struct to be used in your application code.
2039 
2040 🔝 [Back to table of contents](#)
2041 
2042 ### Derived types in C++ {#toxsd9-1-1}
2043 
2044 Extensible and restricted types in XML schemas are derived types from single
2045 simple and complex base types. XML schema derived types are naturally
2046 represented by C++ derived classes using single inheritance. Besides the
2047 concept of extensions versus restrictions, there are two kinds of derived
2048 types: complexTypes with simpleContent, meaning types with XML CDATA values,
2049 and complexTypes with complexContent, meaning types with sub-elements. Both
2050 are permitted to have one or more XML attributes.
2051 
2052 A complexType with simpleContent is defined as a wrapper to contain XML CDATA
2053 values and any number of attributes, see
2054 [wrapper class/struct with simpleContent](#toxsd10-4).
2055 Wrapper class/struct types can form a hierarchy of derived types in C++ using
2056 inheritance. For example:
2057 
2058 ~~~{.cpp}
2059  class xsd__anyType
2060  {
2061  public:
2062  std::string __item; // string to hold any simpleContent
2063  };
2064  class ns__data : public xsd__anyType
2065  {
2066  public:
2067  @ std::string value 1; // extends xsd:anyType with a required attribute
2068  };
2069 ~~~
2070 
2071 The `ns__data` class maps to a complexType in the soapcpp2-generated XML schema:
2072 
2073 <div class="alt">
2074 ~~~{.xml}
2075  <complexType name="string">
2076  <simpleContent>
2077  <extension base="xsd:string">
2078  <attribute name="value" type="xsd:string" use="required"/>
2079  </extension>
2080  </simpleContent>
2081  </complexType>
2082 ~~~
2083 </div>
2084 
2085 The XML value space consists of an element with the string contents an optional
2086 attribute:
2087 
2088 <div class="alt">
2089 ~~~{.xml}
2090  <ns:data value="abc">xyz</ns:data>
2091 ~~~
2092 </div>
2093 
2094 By contrast, a complexType with complexContent typically extends a given base
2095 complexType. For example:
2096 
2097 ~~~{.cpp}
2098  class ns__base
2099  {
2100  public:
2101  std::string name 1;
2102  int number 1;
2103  };
2104  class ns__derived : public ns__base
2105  {
2106  public:
2107  @ std::string value 1; // extends ns:base with an attribute
2108  std::string text 1; // extends ns:base with an element
2109  };
2110 ~~~
2111 
2112 The `ns__base` and `ns__derived` classes maps to complexTypes in the soapcpp2-generated XML schema:
2113 
2114 <div class="alt">
2115 ~~~{.xml}
2116  <complexType name="base">
2117  <sequence>
2118  <element name="name" type="xsd:string" minOccurs="1" maxOccurs="1"/>
2119  <element name="number" type="xsd:int" minOccurs="1" maxOccurs="1"/>
2120  </sequence>
2121  </complexType>
2122  <complexType name="derived">
2123  <complexContent>
2124  <extension base="ns:base">
2125  <sequence>
2126  <element name="text" type="xsd:string" minOccurs="1" maxOccurs="1"/>
2127  </sequence>
2128  </extension>
2129  </complexContent>
2130  <attribute name="value" type="xsd:string" use="required"/>
2131  </complexType>
2132 ~~~
2133 </div>
2134 
2135 The XML value space of `ns__derived` consists of three requires child elements
2136 and an optional attribute:
2137 
2138 <div class="alt">
2139 ~~~{.xml}
2140  <ns:derived value="abc">
2141  <name>def</name>
2142  <number>123</number>
2143  <text>xyz</text>
2144  </ns:derived>
2145 ~~~
2146 </div>
2147 
2148 Derived types can be used for two main purposes in XML schema by extending or
2149 restricting base types. One purpose is to reuse a base type when defining a
2150 derived type, such that common parts do not need to be replicated. The second
2151 purpose is to be able to use a derived type in place of a base type in XML, which
2152 is indicated by an <i>`xsi:type`</i> attribute with the qualified name of the
2153 derived type. Consider for example the following class that uses the
2154 previously declared base types `xsd__anyType` and `ns__base`:
2155 
2156 ~~~{.cpp}
2157  class ns__record
2158  {
2159  public:
2160  xsd__anyType *base1 1; // required element
2161  ns__base *base2 1; // required element
2162  };
2163 ~~~
2164 
2165 We can assign base type values to the `ns_record` members:
2166 
2167 ~~~{.cpp}
2168  ns__record record;
2169  record.base1 = soap_new_xsd__anyType(soap);
2170  record.base2 = soap_new_ns__base(soap);
2171  soap_write_ns__record(soap, &record);
2172 ~~~
2173 
2174 This produces the following XML fragment populated with default values (empty
2175 text for strings and zeros for numbers), where element <i>`base1`</i> has a
2176 simpleContent value and element <i>`base2`</i> has two child elements:
2177 
2178 <div class="alt">
2179 ~~~{.xml}
2180  <ns:record>
2181  <base1></base1>
2182  <base2>
2183  <name></name>
2184  <number>0</number>
2185  </base2>
2186  </ns:record>
2187 ~~~
2188 </div>
2189 
2190 We can also assign derived type values to the `ns_record` members:
2191 
2192 ~~~{.cpp}
2193  ns__record record;
2194  record.base1 = soap_new_ns__data(soap);
2195  record.base2 = soap_new_ns__derived(soap);
2196  soap_write_ns__record(soap, &record);
2197 ~~~
2198 
2199 This produces the following XML fragment populated with default values (empty
2200 text for strings and zeros for numbers), where element <i>`base1`</i> has
2201 schema type <i>`ns:data`</i> with simpleContent and an attribute, and
2202 <i>`base2`</i> has schema type <i>`ns:derived`</i> with three child elements
2203 and an attribute:
2204 
2205 <div class="alt">
2206 ~~~{.xml}
2207  <ns:record>
2208  <base1 xsi:type="ns:data" value=""></base1>
2209  <base2 xsi:type="ns:derived" value="">
2210  <name></name>
2211  <number>0</number>
2212  <text></text>
2213  </base2>
2214  </ns:record>
2215 ~~~
2216 </div>
2217 
2218 Deserialization automatically allocates and assigns a `ns__base` class instance to a
2219 `ns__base` pointer when deserializing the <i>`ns:base`</i> schema type and allocates and
2220 assigns a `ns__derived` class instance to a `ns__base` pointer when deserializing the
2221 <i>`ns:derived`</i> type when an element with <i>`xsi:type="ns:derived"`</i> is
2222 parsed. All classes are extended by soapcpp2 by a `soap_type()` method that
2223 returns the unique `SOAP_TYPE_T` value of the class `T`. This makes it easy to
2224 check whether the deserialized data contains a derived type to implement
2225 type-safe code, for example:
2226 
2227 ~~~{.cpp}
2228  ns__record record;
2229  soap_read_ns__record(soap, &record);
2230  if (record.base1->soap_type() == SOAP_TYPE_ns__data)
2231  std::cout << "Derived ns:data "
2232  << dynamic_cast<ns__data*>(record.base1)->value
2233  << std::endl;
2234  else
2235  std::cout << "Base xsd:anyType" << std::endl;
2236  if (record.base2->soap_type() == SOAP_TYPE_ns__derived)
2237  std::cout << "Derived ns:derived "
2238  << dynamic_cast<ns__derived*>(record.base2)->value
2239  << std::endl;
2240  else
2241  std::cout << "Base ns:base" << std::endl;
2242 ~~~
2243 
2244 This example should use the `SOAP_XML_STRICT` mode flag to initialize the
2245 `soap` context to ensure that all required values are present in the
2246 deserialized structures.
2247 
2248 🔝 [Back to table of contents](#)
2249 
2250 ### Derived types in C {#toxsd9-1-2}
2251 
2252 While single inheritance works well in C++ to represent derived types as we
2253 discussed in the previous section, this will obviously not work in C. Two
2254 methods to serialize derived types in C are presented here. The first method
2255 uses `void*` to serialize anything. The second method is more accurate and is
2256 relatively new in gSOAP.
2257 
2258 To serialize any type is possible with [tagged void pointer members](#toxsd9-12) to
2259 serialize data pointed to by a `void*` member, which can be any serializable
2260 type, such as derived types. For `void*` deserialization to work the XML
2261 parsed must contain an <i>`xsi:type`</i> attribute with a schema type. Only
2262 then can the deserializer instantiate the corresponding serializable C/C++
2263 type. Base types serialized do not require an <i>`xsi:type`</i> to indicate
2264 the base schema type, so this approach is not guaranteed to work and requires a
2265 workaround with an anonymous wrapper struct/class that contains both the base
2266 type and a `void*`. For example:
2267 
2268 ~~~{.cpp}
2269  struct ns__base // a base type
2270  {
2271  char *name 1;
2272  int number 1;
2273  };
2274  struct ns__derived // extends ns__base with two additional members
2275  {
2276  char *name 1;
2277  int number 1;
2278  char *text 1;
2279  @ char *value 1;
2280  };
2281  struct __ns__base // a wrapper, not visible in XML
2282  {
2283  int __type; // the SOAP_TYPE_T pointed to by __self
2284  void *__self; // points to any type
2285  struct ns__base *__self; // wraps ns__base for the current element tag
2286  }
2287  class ns__record
2288  {
2289  struct __ns__base base;
2290  };
2291 ~~~
2292 
2293 The `__ns__base` wrapper wraps the `ns__base` type to (de)serialize the
2294 <i>`base`</i> element that has no <i>`xsi:type`</i> attribute and uses `void*`
2295 to (de)serialize the <i>`base`</i> element that has <i>`xsi:type`</i>
2296 attribute. This works fine at the XML parsing level, but the generated
2297 XML schema components do not accurately represent the derived type, because it
2298 lacks the extension/restriction of the derived type (and the `__ns__base`
2299 wrapper is invisible).
2300 
2301 Using `void*` to represent derived types in a base type wrapper is not very
2302 accurate because we can serialize anything, not just derived types of a given
2303 base type. The wrapper may also hold two values: the base type value and a
2304 derived type value. Furthermore, using arrays or containers that hold base and
2305 derived types becomes quite tricky because an array item could hold both the
2306 base and derived type.
2307 
2308 As of gSOAP version 2.8.75, `wsdl2h -F` option `-F` generates base type structs
2309 extended with transient pointer members to its derived types. To serialize the
2310 base type itself, all of the pointer members are NULL. If one of the pointer
2311 members points to a derived type the derived type is serialized instead.
2312 Deserialization is automatic, in that the base type is deserialized if the
2313 element has no <i>`xsi:type`</i> attribute or the attribute is the base schema
2314 type, and a derived type is deserialized if the element has an
2315 <i>`xsi>type`</i> attribute with the derived schema type.
2316 
2317 This method is fully automated for the wsdl2h tool to generate an interface
2318 header file for soapcpp2 with the type derivations in C. To use this method to
2319 generate code from WSDLs and XSDs, use `wsdl2h -F` option `-F`. This also
2320 works in C++ if desired, but C++ inheritance works fine without this method.
2321 
2322 Using this method with soapcpp2 alone using a manually-specified interface
2323 header file produces the specified type inheritance in the soapcpp2-generated
2324 WSDL and XML schema files as complexType extensions.
2325 
2326 The soapcpp2 tool warns if a derived type has multiple base types. At most one
2327 base type for a derived type may be specified.
2328 
2329 This method with transient pointers to derived types makes it easy to use base
2330 and derived types in C:
2331 
2332 ~~~{.cpp}
2333  struct ns__base // a base type
2334  {
2335  char *name 1;
2336  int number 1;
2337  [ struct ns__derived *ns__derived; ] // points to derived type if non-NULL
2338  };
2339  struct ns__derived // extends ns__base with two additional members
2340  {
2341  char *name 1;
2342  int number 1;
2343  char *text 1;
2344  @ char *value 1;
2345  };
2346  struct ns__record
2347  {
2348  struct ns__base base; // contains base type or derived type value
2349  };
2350 ~~~
2351 
2352 The `ns__base` struct includes the special member `ns__derived` that points to
2353 a `ns__derived` value. This special member must be:
2354 
2355 - a transient member (i.e. non-serializable) by placing the declaration within
2356  `[` and `]`, and
2357 - the member name must match the type name (to be more precise, at least the
2358  initial part of the member name must match the type name as in the example
2359  `ns__derived_` works too).
2360 
2361 To serialize the `ns__base` value requires the `ns__derived` member to be NULL.
2362 To serialize the `ns__derived` value requires the `ns__derived` member to point
2363 to the `ns__derived` value to serialize and the `ns__base` members are
2364 irrelevant.
2365 
2366 We can assign the base type value to the `ns_record::base` member:
2367 
2368 ~~~{.cpp}
2369  struct ns__record record;
2370  soap_default_ns__record(soap, &record);
2371  soap_write_ns__record(soap, &record);
2372 ~~~
2373 
2374 This produces the following XML fragment populated with default values (empty
2375 text for strings and zeros for numbers), where element <i>`base`</i> has two
2376 child elements:
2377 
2378 <div class="alt">
2379 ~~~{.xml}
2380  <ns:record>
2381  <base>
2382  <name></name>
2383  <number>0</number>
2384  </base>
2385  </ns:record>
2386 ~~~
2387 </div>
2388 
2389 We can also assign the derived type value to the `ns_record::base` member:
2390 
2391 ~~~{.cpp}
2392  struct ns__record record;
2393  soap_default_ns__record(soap, &record);
2394  record.base.ns__derived = soap_new_ns__derived(soap, -1);
2395  soap_write_ns__record(soap, &record);
2396 ~~~
2397 
2398 This produces the following XML fragment populated with default values (empty
2399 text for strings and zeros for numbers), where element <i>`base`</i> has schema
2400 type <i>`ns:derived`</i> with three child elements and an attribute:
2401 
2402 <div class="alt">
2403 ~~~{.xml}
2404  <ns:record>
2405  <base xsi:type="ns:derived" value="">
2406  <name></name>
2407  <number>0</number>
2408  <text></text>
2409  </base>
2410  </ns:record>
2411 ~~~
2412 </div>
2413 
2414 Deserialization automatically assigns values to the base members for the
2415 `ns__base` type and populates the `ns__derived` member when a derived type with
2416 <i>`xsi:type="ns:derived"`</i> is parsed. This makes it easy to decompose the
2417 deserialized data:
2418 
2419 ~~~{.cpp}
2420  struct ns__record record;
2421  soap_read_ns__record(soap, &record);
2422  if (record.ns__derived)
2423  printf("Derived type with name=%s number=%d text=%s value=%s\n",
2424  record.ns__derived->name,
2425  record.ns__derived->number,
2426  record.ns__derived->text,
2427  record.ns__derived->value);
2428  else
2429  printf("Base type with name=%s number=%d\n",
2430  record.name,
2431  record.number);
2432 ~~~
2433 
2434 This example requires the `SOAP_XML_STRICT` mode flag to initialize the `soap`
2435 context to ensure that all required values are present in the deserialized
2436 structures, otherwise the `char*` strings may be NULL since XML validation
2437 constraints are not enforced on the XML input.
2438 
2439 Deeper levels of simulated inheritance are possible, for example:
2440 
2441 ~~~{.cpp}
2442  struct ns__base // a base type
2443  {
2444  char *name 1;
2445  int number 1;
2446  [ struct ns__derived *ns__derived; ] // points to derived type if non-NULL
2447  };
2448  struct ns__derived // extends ns__base with two additional members
2449  {
2450  char *name 1;
2451  int number 1;
2452  char *text 1;
2453  @ char *value 1;
2454  [ struct ns__derived_derived *ns__derived_derived; ] // points to derived_derived type if non-NULL
2455  };
2456  struct ns__derived_derived // extends ns__derived with an additional member
2457  {
2458  char *name 1;
2459  int number 1;
2460  char *text 1;
2461  @ char *value 1;
2462  @ char *type 1;
2463  };
2464 ~~~
2465 
2466 This requires two pointer traversals from the base type `ns__base` via
2467 `ns__derived` to reach `ns__derived_derived`.
2468 
2469 🔝 [Back to table of contents](#)
2470 
2471 ### Volatile classes and structs {#toxsd9-2}
2472 
2473 Classes and structs can be declared `volatile` in the interface header file for
2474 soapcpp2, which only has meaning for the gSOAP tools. This annotation means
2475 that these types are already declared elsewhere in your project's source code
2476 and you do not want soapcpp2 to generate code with a second declaration of
2477 these types.
2478 
2479 For example, `struct tm` is declared in the <i>`time.h`</i> library. You can
2480 make it serializable and include a partial list of data members that you want
2481 to serialize:
2482 
2483 ~~~{.cpp}
2484  volatile struct tm
2485  {
2486  int tm_sec; // seconds (0 - 60)
2487  int tm_min; // minutes (0 - 59)
2488  int tm_hour; // hours (0 - 23)
2489  int tm_mday; // day of month (1 - 31)
2490  int tm_mon; // month of year (0 - 11)
2491  int tm_year; // year - 1900
2492  };
2493 ~~~
2494 
2495 You can declare classes and structs `volatile` for any such types you want to
2496 serialize by only providing the public data members you want to serialize.
2497 
2498 In addition, [colon notation](#toxsd2) is a simple and effective way to bind an
2499 existing class or struct to a schema. For example, you can change the `tm` name
2500 as follows without affecting the code that uses `struct tm` generated by
2501 soapcpp2:
2502 
2503 ~~~{.cpp}
2504  volatile struct ns:tm { ... }
2505 ~~~
2506 
2507 This struct maps to a complexType in the soapcpp2-generated XML schema:
2508 
2509 <div class="alt">
2510 ~~~{.xml}
2511  <complexType name="tm">
2512  <sequence>
2513  <element name="tm-sec" type="xsd:int" minOccurs="1" maxOccurs="1"/>
2514  <element name="tm-min" type="xsd:int" minOccurs="1" maxOccurs="1"/>
2515  <element name="tm-hour" type="xsd:int" minOccurs="1" maxOccurs="1"/>
2516  <element name="tm-mday" type="xsd:int" minOccurs="1" maxOccurs="1"/>
2517  <element name="tm-mon" type="xsd:int" minOccurs="1" maxOccurs="1"/>
2518  <element name="tm-year" type="xsd:int" minOccurs="1" maxOccurs="1"/>
2519  </sequence>
2520  </complexType>
2521 ~~~
2522 </div>
2523 
2524 🔝 [Back to table of contents](#)
2525 
2526 ### Mutable classes and structs {#toxsd9-3}
2527 
2528 Classes and structs can be declared `mutable` with the gSOAP tools. This means
2529 that their definition can be spread out over the source code. This promotes the
2530 concept of a class or struct as a *row of named values*, also known as a *named
2531 tuple*, that can be extended at compile time in your source code with additional
2532 members. Because these types differ from the traditional object-oriented
2533 principles and design concepts of classes and objects, constructors and
2534 destructors cannot be defined (also because we cannot guarantee merging these
2535 into one such that all members will be initialized). A default constructor,
2536 copy constructor, assignment operation, and destructor will be assigned
2537 automatically by soapcpp2.
2538 
2539 ~~~{.cpp}
2540  mutable struct ns__tuple
2541  {
2542  @ std::string id;
2543  };
2544 
2545  mutable struct ns__tuple
2546  {
2547  std::string name;
2548  std::string value;
2549  };
2550 ~~~
2551 
2552 The members are collected into one definition generated by soapcpp2. Members
2553 may be repeated from one definition to another, but only if their associated
2554 types are identical. So, for example, a third extension with a `value` member
2555 with a different type fails:
2556 
2557 ~~~{.cpp}
2558  mutable struct ns__tuple
2559  {
2560  float value; // BAD: value is already declared std::string
2561  };
2562 ~~~
2563 
2564 The `mutable` concept has proven to be very useful when declaring and
2565 collecting SOAP Headers for multiple services, which are collected into one
2566 `struct SOAP_ENV__Header` by the soapcpp2 tool.
2567 
2568 🔝 [Back to table of contents](#)
2569 
2570 ### Default and fixed member values {#toxsd9-4}
2571 
2572 Class and struct data members in C and C++ may be declared with an optional
2573 default initialization value that is provided "inline" with the declaration of
2574 the member:
2575 
2576 ~~~{.cpp}
2577  class ns__record
2578  {
2579  public:
2580  std::string name = "Joe";
2581  ...
2582  };
2583 ~~~
2584 
2585 Alternatively, use C++11 default initialization syntax:
2586 
2587 ~~~{.cpp}
2588  class ns__record
2589  {
2590  public:
2591  std::string name { "Joe" };
2592  ...
2593  };
2594 ~~~
2595 
2596 These initializations are made by the default constructor that is added by
2597 soapcpp2 to each class and struct (in C++ only). A constructor is only added
2598 when a default constructor is not already defined with the class declaration.
2599 
2600 You can explicitly (re)initialize an object with these initial values by using
2601 the soapcpp2 auto-generated functions:
2602 
2603 - `void T::soap_default(struct soap*)` for `class T` (C++ only)
2604 
2605 - `void soap_default_T(struct soap*, T*)` for `struct T` (C and C++).
2606 
2607 If `T` is a struct or class that has a `soap` pointer member to a `::soap`
2608 context then this pointer member will be set to the first argument passed to
2609 these functions to initialize their `soap` pointer member.
2610 
2611 Default value initializations can be provided for members that have primitive
2612 types (`bool`, `enum`, `time_t`, numeric and string types).
2613 
2614 Default value initializations of pointer members is permitted, but the effect
2615 is different. To conform to XML schema validation, an attribute member that is
2616 a pointer to a primitive type will be assigned the default value when parsed
2617 from XML. An element member that is a pointer to a primitive type will be
2618 assigned when the element is empty when parsed from XML.
2619 
2620 As of gSOAP 2.8.48 and greater, a fixed value can be assigned with a `==`. A
2621 fixed value is also verified by the parser's validator.
2622 
2623 Default and fixed values for members with or without pointers are best
2624 explained with the following two example fragments.
2625 
2626 A record class with default values for `std::string` (or `std::wstring`)
2627 attributes and elements is declared as follows:
2628 
2629 ~~~{.cpp}
2630  class ns__record_with_default
2631  {
2632  public:
2633  @ std::string a = "A"; // optional XML attribute with default value "A"
2634  @ std::string b 1 = "B"; // required XML attribute with default value "B"
2635  @ std::string *c = "C"; // optional XML attribute with default value "C"
2636  std::string d 0 = "D"; // optional XML element with default value "D"
2637  std::string e = "E"; // required XML element with default value "E"
2638  std::string *f = "F"; // optional XML element with default value "F"
2639  ...
2640  };
2641 ~~~
2642 
2643 Also `std::unique_ptr` and `std::shared_ptr` may be used instead of a regular
2644 pointer to strings.
2645 
2646 With C `char*` (or `const char*`, `const wchar_t*`) strings in a struct, this
2647 becomes:
2648 
2649 ~~~{.cpp}
2650  struct ns__record_with_default
2651  {
2652  @ char* a = "A"; // optional XML attribute with default value "A"
2653  @ char* b 1 = "B"; // required XML attribute with default value "B"
2654  char* e 1 = "E"; // required XML element with default value "E"
2655  char* f = "F"; // optional XML element with default value "F"
2656  ...
2657  };
2658 ~~~
2659 
2660 By contrast to `std::string e`, `char* e` must be marked `1` to make it
2661 required, because pointer members are optional by default.
2662 
2663 Attributes are considered optional by default, unless marked as required with
2664 the occurrence constraint `1`. Elements are considered required unless the
2665 member type is a pointer or if the member is marked optional with occurrence
2666 constraint `0`.
2667 
2668 Instead of default values, fixed values indicate that the attribute or element
2669 must contain that value, and only that value, when provided in XML. A fixed
2670 value is specified with a `==`.
2671 
2672 Attributes with default or fixed values may be omitted in XML. When absent,
2673 the default/fixed value is used at the receiving side, i.e. the deserializer
2674 assigns the default/fixed value when the attribute is absent. Therefore, there
2675 is no need to make attributes with default/fixed values pointer based, because
2676 there is no way to distinguish an omitted attribute from a populated attribute
2677 on the receiving side. The `c` member in the example above can be a
2678 non-pointer for this reason. The wsdl2h tool does not generate pointers for
2679 attributes with default/fixed values.
2680 
2681 Elements with default or fixed values may be optional and the use of
2682 default/fixed values with elements differs from attributes. The default/fixed
2683 value of an element is only used for elements that are empty in the XML payload
2684 received. Omitted optional elements in the XML payload received are simply
2685 absent; no default/fixed value is assigned.
2686 
2687 @note gSOAP 2.8.106 and greater treat `char*` and `wchar_t*` with explicit
2688 default and fixed values differently than previous versions. Versions prior to
2689 2.8.106 assign the default value when the corresponding XML element is absent,
2690 whereas 2.8.106 and greater assign NULL when the XML element is absent, exactly
2691 as documented in this updated version of this document. To revert to the old
2692 behavior, use <b>`soapcpp2 -z4`</b> option <b>`-z4`</b>. The change affects
2693 members `char* f` and `char* l` (see below).
2694 
2695 A record class (can be a struct in C) with fixed values for attributes and
2696 elements is declared as follows:
2697 
2698 ~~~{.cpp}
2699  class ns__record_with_fixed
2700  {
2701  public:
2702  @ std::string g == "G"; // optional XML attribute with fixed value "G"
2703  @ std::string h 1 == "H"; // required XML attribute with fixed value "H"
2704  @ std::string *i == "I"; // optional XML attribute with fixed value "I"
2705  std::string j 0 == "J"; // optional XML element with fixed value "J"
2706  std::string k == "K"; // required XML element with fixed value "K"
2707  std::string *l == "L"; // optional XML element with fixed value "L"
2708  ...
2709  };
2710 ~~~
2711 
2712 With C `char*` (or `const char*`, `const wchar_t*`) strings in a struct, this
2713 becomes:
2714 
2715 ~~~{.cpp}
2716  struct ns__record_with_fixed
2717  {
2718  @ char* g == "G"; // optional XML attribute with fixed value "G"
2719  @ char* h 1 == "H"; // required XML attribute with fixed value "H"
2720  char* k 1 == "K"; // required XML element with fixed value "K"
2721  char* l == "L"; // optional XML element with fixed value "L"
2722  ...
2723  };
2724 ~~~
2725 
2726 The XML schema validation rules for the examples above are as follows:
2727 
2728 Member | Notes
2729 ------ | ---------------------------------------------------------------------
2730 `a` | attribute may appear once; if it does not appear its value is "A", otherwise its value is that given (also note: instantiating `ns__record_with_default` assigns the default value "A")
2731 `b` | has no effect when parsing XML (but note: instantiating `ns__record_with_default` assigns the default value "B")
2732 `c` | attribute may appear once; if it does not appear its value is "C", otherwise its value is that given (also note: instantiating `ns__record_with_default` assigns NULL)
2733 `d` | element may appear once; if it does not appear or if it is empty, its value is "D"; otherwise its value is that given (also note: instantiating `ns__record_with_default` assigns the default value "D")
2734 `e` | has no effect when parsing XML (but note: instantiating `ns__record_with_default` assigns the default value "E")
2735 `f` | element may appear once; if it does not appear it is not provided; if it does appear and it is empty, its value is "F"; otherwise its value is that given (also note: instantiating `ns__record_with_default` assigns NULL)
2736 `g` | attribute may appear once; if it does not appear its value is "G", if it does not appear its value is "G" (also note: instantiating `ns__record_with_fixed` assigns the fixed value "G")
2737 `h` | attribute must appear once, its value must be "H" (also note: instantiating `ns__record_with_fixed` assigns the fixed value "H")
2738 `i` | attribute may appear once; if it does not appear its value is "I", if it does not appear its value is "I" (also note: instantiating `ns__record_with_fixed` assigns NULL)
2739 `j` | element may appear once, if it does not appear it is not provided; if it does appear and it is empty, its value is "J"; if it does appear and it is not empty, its value must be "J" (also note: instantiating `ns__record_with_fixed` assigns the fixed value "J")
2740 `k` | element must appear once, its value must be "K" (also note: instantiating `ns__record_with_fixed` assigns the fixed value "K")
2741 `l` | element may appear once, if it does not appear it is not provided; if it does appear and it is empty, its value is "J"; if it does appear and it is not empty, its value must be "J" (also note: instantiating `ns__record_with_fixed` assigns NULL)
2742 
2743 Members of type `char[N]` (fixed length string) can have default and fixed
2744 values, when <b>`soapcpp2 -b`</b> option <b>`-b`</b> is used. Also `char**`
2745 (pointer to a string) members can have default and fixed values. However,
2746 members of this type will be initialized to NULL. The default/fixed values
2747 will be assigned with the same rules as for `char*` when deserialized from XML.
2748 
2749 @see Section [operations on classes and structs](#toxsd9-14).
2750 
2751 🔝 [Back to table of contents](#)
2752 
2753 ### Attribute members {#toxsd9-5}
2754 
2755 Class and struct data members are declared as XML attributes by annotating
2756 their type with a `@` qualifier:
2757 
2758 ~~~{.cpp}
2759  class ns__record
2760  {
2761  public:
2762  @ std::string name; // required (non-pointer means required)
2763  @ uint64_t SSN; // required (non-pointer means required)
2764  ns__record *spouse; // optional (pointer means minOccurs=0)
2765  };
2766 ~~~
2767 
2768 This class maps to a complexType in the soapcpp2-generated XML schema:
2769 
2770 <div class="alt">
2771 ~~~{.xml}
2772  <complexType name="record">
2773  <sequence>
2774  <element name="spouse" type="ns:record" minOccurs="0" maxOccurs="1" nillable="true"/>
2775  </sequence>
2776  <attribute name="name" type="xsd:string" use="required"/>
2777  <attribute name="SSN" type="xsd:unsignedLong" use="required"/>
2778  </complexType>
2779 ~~~
2780 </div>
2781 
2782 An example XML instance of `ns__record` is:
2783 
2784 <div class="alt">
2785 ~~~{.xml}
2786  <ns:record xmlns:ns="urn:types" name="Joe" SSN="1234567890">
2787  <spouse name="Jane" SSN="1987654320">
2788  </spouse>
2789  </ns:record>
2790 ~~~
2791 </div>
2792 
2793 Attribute data members are restricted to primitive types (`bool`, `enum`,
2794 `time_t`, numeric and string types), `xsd__hexBinary`, `xsd__base64Binary`, and
2795 custom serializers, such as `xsd__dateTime`. Custom serializers for types that
2796 may be used as attributes should define `soap_s2T` and `soap_T2s` functions that
2797 convert values of type `T` to strings and back.
2798 
2799 Attribute data members can be pointers and smart pointers to these types, which
2800 permits attributes to be optional.
2801 
2802 🔝 [Back to table of contents](#)
2803 
2804 ### Backtick XML tags {#toxsd9-5-1}
2805 
2806 The XML tag name of a class/struct member is the name of the member with the
2807 usual XML tag translation, see [colon notation](#toxsd2).
2808 
2809 To override the standard translation of identifier names to XML tag names of
2810 attributes and elements, add the XML tag name in backticks (requires gSOAP
2811 2.8.30 or greater):
2812 
2813 ~~~{.cpp}
2814  class ns__record
2815  {
2816  public:
2817  @ std::string name `full-name`;
2818  @ uint64_t SSN `tax-id`;
2819  ns__record *spouse `married-to`;
2820  };
2821 ~~~
2822 
2823 This class maps to a complexType in the soapcpp2-generated XML schema:
2824 
2825 <div class="alt">
2826 ~~~{.xml}
2827  <complexType name="record">
2828  <sequence>
2829  <element name="married-to" type="ns:record" minOccurs="0" maxOccurs="1"/>
2830  </sequence>
2831  <attribute name="full-name" type="xsd:string" use="required"/>
2832  <attribute name="tax-id" type="xsd:unsignedLong" use="required"/>
2833  </complexType>
2834 ~~~
2835 </div>
2836 
2837 An example XML instance of `ns__record` is:
2838 
2839 <div class="alt">
2840 ~~~{.xml}
2841  <ns:record xmlns:ns="urn:types" full-name="Joe" tax-id="1234567890">
2842  <married-to full-name="Jane" tax-id="1987654320">
2843  </married-to>
2844  </ns:record>
2845 ~~~
2846 </div>
2847 
2848 A backtick XML tag name may contain any non-empty sequence of ASCII and UTF-8
2849 characters except white space and the backtick character. A backtick tag can
2850 be combined with member constraints and default member initializers:
2851 
2852 ~~~{.cpp}
2853  @ uint64_t SSN `tax-id` 0:1 = 999;
2854 ~~~
2855 
2856 🔝 [Back to table of contents](#)
2857 
2858 ### Qualified and unqualified members {#toxsd9-6}
2859 
2860 Class, struct, and union data members are mapped to namespace qualified or
2861 unqualified tag names of local elements and attributes. If a data member has
2862 no prefix then the default form of qualification is applied based on the
2863 element/attribute form that is declared with the XML schema of the class, struct,
2864 or union type. If the member name has a namespace prefix by colon notation,
2865 then the prefix overrules the default (un)qualified form. Therefore,
2866 [colon notation](#toxsd2) is an effective mechanism to control qualification of
2867 tag names of individual members of classes, structs, and unions.
2868 
2869 The XML schema elementFormDefault and attributeFormDefault declarations control
2870 the tag name qualification of local elements and attributes, respectively.
2871 
2872 - "unqualified" indicates that local elements/attributes are not qualified with
2873  the namespace prefix.
2874 
2875 - "qualified" indicates that local elements/attributes must be qualified with
2876  the namespace prefix.
2877 
2878 Individual schema declarations of local elements and attributes may overrule
2879 this by using the form declaration in an XML schema and by using colon notation
2880 to add namespace prefixes to class, struct, and union members in the header
2881 file for soapcpp2.
2882 
2883 Consider for example an `ns__record` class in the `ns` namespace in which local
2884 elements are qualified and local attributes are unqualified by default:
2885 
2886 ~~~{.cpp}
2887  //gsoap ns schema namespace: urn:types
2888  //gsoap ns schema elementForm: qualified
2889  //gsoap ns schema attributeForm: unqualified
2890  class ns__record
2891  {
2892  public:
2893  @ std::string name;
2894  @ uint64_t SSN;
2895  ns__record *spouse;
2896  };
2897 ~~~
2898 
2899 This class maps to a complexType in the soapcpp2-generated XML schema with
2900 targetNamespace "urn:types", elementFormDefault qualified and
2901 attributeFormDefault unqualified:
2902 
2903 <div class="alt">
2904 ~~~{.xml}
2905  <schema targetNamespace="urn:types"
2906  ...
2907  elementFormDefault="qualified"
2908  attributeFormDefault="unqualified"
2909  ... >
2910  <complexType name="record">
2911  <sequence>
2912  <element name="spouse" type="ns:record" minOccurs="0" maxOccurs="1"/>
2913  </sequence>
2914  <attribute name="name" type="xsd:string" use="required"/>
2915  <attribute name="SSN" type="xsd:unsignedLong" use="required"/>
2916  </complexType>
2917  </schema>
2918 ~~~
2919 </div>
2920 
2921 An example XML instance of `ns__record` is:
2922 
2923 <div class="alt">
2924 ~~~{.xml}
2925  <ns:record xmlns:ns="urn:types" name="Joe" SSN="1234567890">
2926  <ns:spouse> name="Jane" SSN="1987654320">
2927  </ns:spouse>
2928  </ns:record>
2929 ~~~
2930 </div>
2931 
2932 Here the root element <i>`<ns:record>`</i> is qualified because it is a root
2933 element of the XML schema with target namespace "urn:types". Its local element
2934 <i>`<ns:spouse>`</i> is namespace qualified because the elementFormDefault of
2935 local elements is qualified. Attributes are unqualified.
2936 
2937 The default namespace (un)qualification of local elements and attributes can be
2938 overruled by adding a prefix to the member name by using colon notation:
2939 
2940 ~~~{.cpp}
2941  //gsoap ns schema namespace: urn:types
2942  //gsoap ns schema elementForm: qualified
2943  //gsoap ns schema attributeForm: unqualified
2944  class ns__record
2945  {
2946  public:
2947  @ std::string ns:name; // 'ns:' qualified
2948  @ uint64_t SSN;
2949  ns__record *:spouse; // ':' unqualified (empty prefix)
2950  };
2951 ~~~
2952 
2953 The colon notation for member <i>`ns:name`</i> forces qualification of its attribute
2954 tag in XML. The colon notation for member <i>`:spouse`</i> removes qualification from
2955 its local element tag:
2956 
2957 <div class="alt">
2958 ~~~{.xml}
2959  <schema targetNamespace="urn:types"
2960  ...
2961  elementFormDefault="unqualified"
2962  attributeFormDefault="unqualified"
2963  ... >
2964  <complexType name="record">
2965  <sequence>
2966  <element name="spouse" type="ns:record" minOccurs="0" maxOccurs="1" form="unqualified"/>
2967  </sequence>
2968  <attribute name="name" type="xsd:string" use="required" form="qualified"/>
2969  <attribute name="SSN" type="xsd:unsignedLong" use="required"/>
2970  </complexType>
2971  </schema>
2972 ~~~
2973 </div>
2974 
2975 XML instances of `ns__record` have unqualified spouse elements and qualified
2976 ns:name attributes:
2977 
2978 <div class="alt">
2979 ~~~{.xml}
2980  <ns:record xmlns:ns="urn:types" ns:name="Joe" SSN="1234567890">
2981  <spouse> ns:name="Jane" SSN="1987654320">
2982  </spouse>
2983  </ns:record>
2984 ~~~
2985 </div>
2986 
2987 Members of a class or struct can also be prefixed using the `prefix__name`
2988 convention or using colon notation `prefix:name`. However, this has a
2989 different effect by referring to global (root) elements and attributes, see
2990 [document root element definitions](#toxsd9-7).
2991 
2992 [Backtick XML tags](#toxsd9-5-1) can be used in place of the member name
2993 annotations and will achieve the same effect as described when these tag names
2994 are (un)qualified (requires gSOAP 2.8.30 or greater).
2995 
2996 @note You must declare a target namespace with a `//gsoap ns schema namespace:`
2997 directive to enable the `elementForm` and `attributeForm` directives in order
2998 to generate valid XML schemas with soapcpp2. See [directives](#directives) for
2999 more details.
3000 
3001 🔝 [Back to table of contents](#)
3002 
3003 ### Defining document root elements {#toxsd9-7}
3004 
3005 To define and reference XML document root elements we use type names that start
3006 with an underscore:
3007 
3008 ~~~{.cpp}
3009  class _ns__record
3010 ~~~
3011 
3012 Alternatively, we can use a `typedef` to define a document root element with a
3013 given type:
3014 
3015 ~~~{.cpp}
3016  typedef ns__record _ns__record;
3017 ~~~
3018 
3019 This `typedef` maps to a global root element that is added to the
3020 soapcpp2-generated XML schema:
3021 
3022 <div class="alt">
3023 ~~~{.xml}
3024  <element name="record" type="ns:record"/>
3025 ~~~
3026 </div>
3027 
3028 An example XML instance of `_ns__record` is:
3029 
3030 <div class="alt">
3031 ~~~{.xml}
3032  <ns:record xmlns:ns="urn:types">
3033  <name>Joe</name>
3034  <SSN>1234567890</SSN>
3035  <spouse>
3036  <name>Jane</name>
3037  <SSN>1987654320</SSN>
3038  </spouse>
3039  </ns:record>
3040 ~~~
3041 </div>
3042 
3043 Global-level element/attribute definitions are also referenced and/or added to
3044 the generated XML schema when serializable data members reference these by
3045 their qualified name:
3046 
3047 ~~~{.cpp}
3048  typedef std::string _ns__name 1 : 100;
3049  class _ns__record
3050  {
3051  public:
3052  @ _QName xsi__type; // built-in XSD attribute xsi:type
3053  _ns__name ns__name; // ref to global ns:name element
3054  uint64_t SSN;
3055  _ns__record *spouse;
3056  };
3057 ~~~
3058 
3059 These types map to the following comonents in the soapcpp2-generated XML
3060 schema:
3061 
3062 <div class="alt">
3063 ~~~{.xml}
3064  <simpleType name="name">
3065  <restriction base="xsd:string">
3066  <minLength value="1"/>
3067  <maxLength value="100"/>
3068  </restriction>
3069  </simpleType>
3070  <element name="name" type="ns:name"/>
3071  <complexType name="record">
3072  <sequence>
3073  <element ref="ns:name" minOccurs="1" maxOccurs="1"/>
3074  <element name="SSN" type="xsd:unsignedLong" minOccurs="1" maxOccurs="1"/>
3075  <element name="spouse" type="ns:record" minOccurs="0" maxOccurs="1"/>
3076  </sequence>
3077  <attribute ref="xsi:type" use="optional"/>
3078  </complexType>
3079  <element name="record" type="ns:record"/>
3080 ~~~
3081 </div>
3082 
3083 Use only use qualified member names when their types match the global-level
3084 element types that they refer to. For example:
3085 
3086 ~~~{.cpp}
3087  typedef std::string _ns__name; // global element ns:name of type xsd:string
3088  class _ns__record
3089  {
3090  public:
3091  int ns__name; // BAD: global element ns:name is NOT type int
3092  _ns__record ns__record; // OK: ns:record is a global-level root element
3093  ...
3094  };
3095 ~~~
3096 
3097 Therefore, we recommend to use qualified member names only when necessary to
3098 refer to standard XSD elements and attributes, such as `xsi__type`, and
3099 `xsd__lang`.
3100 
3101 By contrast, colon notation has the desired effect to (un)qualify local tag
3102 names by overruling the default element/attribute namespace qualification, see
3103 [qualified and unqualified members](#toxsd9-6).
3104 
3105 As an alternative to prefixing member names, use the backtick tag (requires
3106 gSOAP 2.8.30 or greater):
3107 
3108 ~~~{.cpp}
3109  typedef std::string _ns__name 1 : 100;
3110  class _ns__record
3111  {
3112  public:
3113  @ _QName t <i>`xsi:type`</i>; // built-in XSD attribute xsi:type
3114  _ns__name s <i>`ns:name`</i>; // ref to global ns:name element
3115  uint64_t SSN;
3116  _ns__record *spouse;
3117  };
3118 ~~~
3119 
3120 🔝 [Back to table of contents](#)
3121 
3122 ### (Smart) pointer members and their occurrence constraints {#toxsd9-8}
3123 
3124 A public pointer-typed data member is serialized by following its (smart)
3125 pointer(s) to the value pointed to. To serialize pointers to dynamic arrays of
3126 data, please see the next section on
3127 [container and array members and their occurrence constraints](#toxsd9-9).
3128 
3129 Pointers that are NULL and smart pointers that are empty are serialized to
3130 produce omitted element and attribute values, unless an element is required
3131 and is nillable (struct/class members marked with `nullptr`) in which case the
3132 element is rendered as an empty element with <i>`xsi:nil="true"`</i>.
3133 
3134 To control the occurrence requirements of pointer-based data members,
3135 occurrence constraints are associated with data members in the form of a range
3136 `minOccurs : maxOccurs`. For non-repeatable (meaning, not a container or array)
3137 data members, there are only three reasonable occurrence constraints:
3138 
3139 - `0:0` means that this element or attribute is prohibited.
3140 
3141 - `0:1` means that this element or attribute is optional.
3142 
3143 - `1:1` means that this element or attribute is required.
3144 
3145 Pointer-based data members have a default `0:1` occurrence constraint, making
3146 them optional, and their XML schema local element/attribute definition is
3147 marked as nillable. Non-pointer data members have a default `1:1` occurence
3148 constraint, making them required.
3149 
3150 A `nullptr` occurrence constraint may be applicable to required elements that
3151 are nillable pointer types, thus `nullptr 1:1`. This indicates that the
3152 element is nillable (can be `NULL` or `nullptr`). A pointer data member that
3153 is explicitly marked as required and nillable with `nullptr 1:1` will be
3154 serialized as an element with an <i>`xsi:nil`</i> attribute, thus effectively
3155 revealing the NULL property of its value.
3156 
3157 A non-pointer data member that is explicitly marked as optional with `0:1` will
3158 be set to its default value when no XML value is presented to the deserializer.
3159 A default value can be assigned to a data member that has a primitive type or
3160 is a (smart) pointer to primitive type.
3161 
3162 Consider for example:
3163 
3164 ~~~{.cpp}
3165  class ns__record
3166  {
3167  public:
3168  std::shared_ptr<std::string> name; // optional (pointer means minOccurs=0)
3169  uint64_t SSN 0:1 = 999; // force optional with default 999
3170  ns__record *spouse nullptr 1:1; // force required and nillabe when absent
3171  };
3172 ~~~
3173 
3174 This class maps to a complexType in the soapcpp2-generated XML schema:
3175 
3176 <div class="alt">
3177 ~~~{.xml}
3178  <complexType name="record">
3179  <sequence>
3180  <element name="name" type="xsd:string" minOccurs="0" maxOccurs="1" nillable="true"/>
3181  <element name="SSN" type="xsd:unsignedLong" minOccurs="0" maxOccurs="1" default="999"/>
3182  <element name="spouse" type="ns:record" minOccurs="1" maxOccurs="1" nillable="true"/>
3183  </sequence>
3184  </complexType>
3185 ~~~
3186 </div>
3187 
3188 An example XML instance of `ns__record` with its `name` string value set to
3189 `Joe`, `SSN` set to its default, and `spouse` set to NULL:
3190 
3191 <div class="alt">
3192 ~~~{.xml}
3193  <ns:record xmlns:ns="urn:types" ...>
3194  <name>Joe</name>
3195  <SSN>999</SSN>
3196  <spouse xsi:nil="true"/>
3197  </ns:record>
3198 ~~~
3199 </div>
3200 
3201 @note In general, a smart pointer is simply declared as a `volatile` template
3202 in a interface header file for soapcpp2:
3203 ~~~{.cpp}
3204  volatile template <class T> class NAMESPACE::shared_ptr;
3205 ~~~
3206 
3207 @note The soapcpp2 tool generates code that uses `NAMESPACE::shared_ptr` and
3208 `NAMESPACE::make_shared` to create shared pointers to objects, where
3209 `NAMESPACE` is any valid C++ namespace such as `std` and `boost` if you have
3210 Boost installed.
3211 
3212 🔝 [Back to table of contents](#)
3213 
3214 ### Container and array members and their occurrence constraints {#toxsd9-9}
3215 
3216 Class and struct data member types that are containers `std::deque`,
3217 `std::list`, `std::vector` and `std::set` are serialized as a collection of
3218 the values they contain. You can also serialize dynamic arrays, which is the
3219 alternative for C to store collections of data. Let's start with STL containers.
3220 
3221 You can use `std::deque`, `std::list`, `std::vector`, and `std::set` containers
3222 by importing:
3223 
3224 ~~~{.cpp}
3225  #import "import/stl.h" // import all containers
3226  #import "import/stldeque.h" // import deque
3227  #import "import/stllist.h" // import list
3228  #import "import/stlvector.h" // import vector
3229  #import "import/stlset.h" // import set
3230 ~~~
3231 
3232 For example, to use a vector data mamber to store names in a record:
3233 
3234 ~~~{.cpp}
3235  #import "import/stlvector.h"
3236  class ns__record
3237  {
3238  public:
3239  std::vector<std::string> names;
3240  uint64_t SSN;
3241  };
3242 ~~~
3243 
3244 To limit the number of names in the vector within reasonable bounds, occurrence
3245 constraints are associated with the container. Occurrence constraints are of
3246 the form `minOccurs : maxOccurs`:
3247 
3248 ~~~{.cpp}
3249  #import "import/stlvector.h"
3250  class ns__record
3251  {
3252  public:
3253  std::vector<std::string> names 1:10;
3254  uint64_t SSN;
3255  };
3256 ~~~
3257 
3258 This class maps to a complexType in the soapcpp2-generated XML schema:
3259 
3260 <div class="alt">
3261 ~~~{.xml}
3262  <complexType name="record">
3263  <sequence>
3264  <element name="name" type="xsd:string" minOccurs="1" maxOccurs="10"/>
3265  <element name="SSN" type="xsd:unsignedLong" minOccurs="1" maxOccurs="1"/>
3266  </sequence>
3267  </complexType>
3268 ~~~
3269 </div>
3270 
3271 @note In general, a container is simply declared as a template in an interface
3272 header file for soapcpp2. All class templates are considered containers
3273 (except when declared `volatile`, see smart pointers). For example,
3274 `std::vector` is declared in <i>`gsoap/import/stlvector.h`</i> as:
3275 ~~~{.cpp}
3276  template <class T> class std::vector;
3277 ~~~
3278 
3279 @note You can define and use your own containers. The soapcpp2 tool generates
3280 code that uses the following members of the `template <typename T> class C`
3281 container:
3282 ~~~{.cpp}
3283  void C::clear()
3284  C::iterator C::begin()
3285  C::const_iterator C::begin() const
3286  C::iterator C::end()
3287  C::const_iterator C::end() const
3288  size_t C::size() const
3289  C::iterator C::insert(C::iterator pos, const T& val)
3290 ~~~
3291 
3292 @note For more details see the example `simple_vector` container with
3293 documentation in the package under <i>`gsoap/samples/template`</i>.
3294 
3295 Because C does not support a container template library, we can use a
3296 dynamically-sized array of values. This array is declared as a size-pointer
3297 pair of members within a struct or class. The array size information is stored
3298 in a special size tag member with the name `__size` or `__sizeX`, where `X` can
3299 be any name, or by an `$int` member to identify the member as a special size
3300 tag:
3301 
3302 ~~~{.cpp}
3303  struct ns__record
3304  {
3305  $ int sizeofnames; // array size
3306  char* *names; // array of char* names
3307  uint64_t SSN;
3308  };
3309 ~~~
3310 
3311 This struct maps to a complexType in the soapcpp2-generated XML schema:
3312 
3313 <div class="alt">
3314 ~~~{.xml}
3315  <complexType name="record">
3316  <sequence>
3317  <element name="name" type="xsd:string" minOccurs="0" maxOccurs="unbounded" nillable="true"/>
3318  <element name="SSN" type="xsd:unsignedLong" minOccurs="1" maxOccurs="1"/>
3319  </sequence>
3320  </complexType>
3321 ~~~
3322 </div>
3323 
3324 To limit the number of names in the array within reasonable bounds, occurrence
3325 constraints are associated with the array size member. Occurrence constraints
3326 are of the form `minOccurs : maxOccurs`:
3327 
3328 ~~~{.cpp}
3329  struct ns__record
3330  {
3331  $ int sizeofnames 1:10; // array size 1..10
3332  char* *names; // array of one to ten char* names
3333  uint64_t SSN;
3334  };
3335 ~~~
3336 
3337 This struct maps to a complexType in the soapcpp2-generated XML schema:
3338 
3339 <div class="alt">
3340 ~~~{.xml}
3341  <complexType name="record">
3342  <sequence>
3343  <element name="name" type="xsd:string" minOccurs="1" maxOccurs="10" nillable="true"/>
3344  <element name="SSN" type="xsd:unsignedLong" minOccurs="1" maxOccurs="1"/>
3345  </sequence>
3346  </complexType>
3347 ~~~
3348 </div>
3349 
3350 Arrays can also be declared as nested elements, similar to SOAP-encoded dynamic arrays, and these arrays can be used with or without SOAP applications. This requires a separate struct or class with the name of the SOAP array, which should not be qualified with a namespace prefix:
3351 
3352 ~~~{.cpp}
3353  struct ArrayOfstring
3354  {
3355  char* *__ptr 1:100; // array of 1..100 strings
3356  int __size; // array size
3357  };
3358  struct ns__record
3359  {
3360  struct ArrayOfstring names; // array of char* names
3361  uint64_t SSN;
3362  };
3363 ~~~
3364 
3365 The `ns__record` struct maps to a complexType that references the <i>`ArrayOfstring`</i> complexType with an sequence of 1 to 100 <i>`item`</i> elements:
3366 
3367 <div class="alt">
3368 ~~~{.xml}
3369  <complexType name="ArrayOfstring">
3370  <sequence>
3371  <element name="item" type="xsd:string" minOccurs="1" maxOccurs="100"/>
3372  </sequence>
3373  </complexType>
3374  <complexType name="record">
3375  <sequence>
3376  <element name="names" type="ns:ArrayOfstring" minOccurs="1" maxOccurs="1"/>
3377  <element name="SSN" type="xsd:unsignedLong" minOccurs="1" maxOccurs="1"/>
3378  </sequence>
3379  </complexType>
3380 ~~~
3381 </div>
3382 
3383 To change the <i>`item`</i> element name in the WSDL, XML schema, and XML messages, use `__ptrName` where `Name` is the name you want to use.
3384 
3385 @note When <b>`soapcpp2 -e`</b> option <b>`-e`</b> is used, the <i>`ArrayOfstring`</i> becomes a SOAP-encoded array for SOAP 1.1/1.2 RPC encoded messaging:
3386 <div class="alt">
3387 ~~~{.xml}
3388  <import namespace="http://schemas.xmlsoap.org/soap/encoding/"/>
3389  <complexType name="ArrayOfstring">
3390  <complexContent>
3391  <restriction base="SOAP-ENC:Array">
3392  <sequence>
3393  <element name="item" type="xsd:string" minOccurs="1" maxOccurs="100"/>
3394  </sequence>
3395  <attribute ref="SOAP-ENC:arrayType" WSDL:arrayType="xsd:string[]"/>
3396  </restriction>
3397  </complexContent>
3398  </complexType>
3399  <complexType name="record">
3400  <sequence>
3401  <element name="names" type="ns:ArrayOfstring" minOccurs="1" maxOccurs="1"/>
3402  <element name="SSN" type="xsd:unsignedLong" minOccurs="1" maxOccurs="1"/>
3403  </sequence>
3404  </complexType>
3405 ~~~
3406 </div>
3407 
3408 Fixed-size arrays can be used to store a fixed number of values:
3409 
3410 ~~~{.cpp}
3411  struct ns__record
3412  {
3413  char* names[10]; // array of 10 char* names
3414  uint64_t SSN;
3415  };
3416 ~~~
3417 
3418 The fixed-size array is similar to a SOAP-encoded array, which can be used with or without SOAP applications. This struct maps to a complexType that references a <i>`Array10Ofstring`</i> complexType with ten <i>`item`</i> elements:
3419 
3420 <div class="alt">
3421 ~~~{.xml}
3422  <complexType name="record">
3423  <sequence>
3424  <element name="names" type="ns:Array10Ofstring" minOccurs="1" maxOccurs="1"/>
3425  <element name="SSN" type="xsd:unsignedLong" minOccurs="1" maxOccurs="1"/>
3426  </sequence>
3427  </complexType>
3428  <complexType name="Array10Ofstring">
3429  <sequence>
3430  <element name="item" type="xsd:string" minOccurs="0" maxOccurs="10"/>
3431  </sequence>
3432  </complexType>
3433 ~~~
3434 </div>
3435 
3436 @note When <b>`soapcpp2 -e`</b> option <b>`-e`</b> is used, the <i>`Array10Ofstring`</i> becomes a SOAP-encoded array for SOAP 1.1/1.2 RPC encoded messaging, see previous note.
3437 
3438 🔝 [Back to table of contents](#)
3439 
3440 ### Sequencing with hidden members {#toxsd9-10}
3441 
3442 A member becomes a hidden XML element, i.e. not visibly rendered in XML, when
3443 its name starts with a double underscore. This makes it possible to sequence a
3444 collection of data members, basically by forming a sequence of elements that
3445 can be optional or repeated together.
3446 
3447 To create a sequence of members that are optional, use a pointer-based hidden
3448 member that is a struct with the collection of members to sequence:
3449 
3450 ~~~{.cpp}
3451  struct ns__record
3452  {
3453  std::string name; // required name
3454  struct __ns__optional
3455  {
3456  uint64_t SSN; // SSN in optional group
3457  std::string phone; // phone number in optional group
3458  } *__optional; // optional group
3459  };
3460 ~~~
3461 
3462 Here we used a hidden struct type `__ns__optional` which starts with a double
3463 underscore, because we do not want to define a new global type for the XML
3464 schema we generate. We just need a unique name for a structure that sequences
3465 the two members.
3466 
3467 This struct maps to a complexType in the soapcpp2-generated XML schema:
3468 
3469 <div class="alt">
3470 ~~~{.xml}
3471  <complexType name="record">
3472  <sequence>
3473  <element name="name" type="xsd:string" minOccurs="1" maxOccurs="1"/>
3474  <sequence minOccurs="0" maxOccurs="1">
3475  <element name="SSN" type="xsd:unsignedLong" minOccurs="1" maxOccurs="1"/>
3476  <element name="phone" type="xsd:string" minOccurs="1" maxOccurs="1"/>
3477  </sequence>
3478  </sequence>
3479  </complexType>
3480 ~~~
3481 </div>
3482 
3483 The `name` member is a required element of the <i>`ns:record`</i> complexType.
3484 The <i>`ns:record`</i> complexType has an optional sequence of `SSN` and
3485 `phone` elements.
3486 
3487 To create repetitions of a sequence of members, use an array as follows:
3488 
3489 ~~~{.cpp}
3490  struct ns__record
3491  {
3492  std::string name; // required name
3493  $ int sizeofarray; // size of group array
3494  struct __ns__array
3495  {
3496  uint64_t SSN; // SSN in group
3497  std::string phone; // phone number in group
3498  } *__array; // group array
3499  };
3500 ~~~
3501 
3502 This struct maps to a complexType in the soapcpp2-generated XML schema:
3503 
3504 <div class="alt">
3505 ~~~{.xml}
3506  <complexType name="record">
3507  <sequence>
3508  <element name="name" type="xsd:string" minOccurs="1" maxOccurs="1"/>
3509  <sequence minOccurs="0" maxOccurs="unbounded">
3510  <element name="SSN" type="xsd:unsignedLong" minOccurs="1" maxOccurs="1"/>
3511  <element name="phone" type="xsd:string" minOccurs="1" maxOccurs="1"/>
3512  </sequence>
3513  </sequence>
3514  </complexType>
3515 ~~~
3516 </div>
3517 
3518 The `name` member is a required element of the <i>`ns:record`</i> complexType.
3519 The <i>`ns:record`</i> complexType has a potentially unbounded sequence of
3520 `SSN` and `phone` elements. You can specify array bounds instead of zero to
3521 unbounded, see [container and array members and their occurrence constraints](#toxsd9-9).
3522 
3523 The XML value space consists of a sequence of SSN and phone elements:
3524 
3525 <div class="alt">
3526 ~~~{.xml}
3527  <ns:record>
3528  <name>numbers</name>
3529  <SSN>1234567890</SSN>
3530  <phone>555-123-4567</phone>
3531  <SSN>1987654320</SSN>
3532  <phone>555-789-1234</phone>
3533  <SSN>2345678901</SSN>
3534  <phone>555-987-6543</phone>
3535  </ns:record>
3536 ~~~
3537 </div>
3538 
3539 🔝 [Back to table of contents](#)
3540 
3541 ### Tagged union members {#toxsd9-11}
3542 
3543 A union member in a class or in a struct cannot be serialized unless a
3544 discriminating *variant selector* member is provided that tells the serializer
3545 which union field to serialize. This effectively creates a *tagged union*.
3546 
3547 The variant selector is associated with the union as a selector-union pair of members.
3548 The variant selector is a member with the name `__union` or `__unionX`, where
3549 `X` can be any name, or by an `$int` member to identify the member as a variant
3550 selector tag:
3551 
3552 ~~~{.cpp}
3553  class ns__record
3554  {
3555  public:
3556  $ int xORnORs; // variant selector with values SOAP_UNION_fieldname
3557  union ns__choice
3558  {
3559  float x;
3560  int n;
3561  char *s;
3562  } u;
3563  std::string name;
3564  };
3565 ~~~
3566 
3567 The variant selector values are auto-generated based on the union name `choice`
3568 and the names of its members `x`, `n`, and `s`:
3569 
3570 - `xORnORs = SOAP_UNION_ns__choice_x` when `u.x` is valid.
3571 
3572 - `xORnORs = SOAP_UNION_ns__choice_n` when `u.n` is valid.
3573 
3574 - `xORnORs = SOAP_UNION_ns__choice_s` when `u.s` is valid.
3575 
3576 - `xORnORs = 0` when none are valid (should only be used with great care,
3577  because XSD validation may fail when content is required but absent).
3578 
3579 This class maps to a complexType with a sequence and choice in the
3580 soapcpp2-generated XML schema:
3581 
3582 <div class="alt">
3583 ~~~{.xml}
3584  <complexType name="record">
3585  <sequence>
3586  <choice>
3587  <element name="x" type="xsd:float" minOccurs="1" maxOccurs="1"/>
3588  <element name="n" type="xsd:int" minOccurs="1" maxOccurs="1"/>
3589  <element name="s" type="xsd:string" minOccurs="0" maxOccurs="1" nillable="true"/>
3590  </choice>
3591  <element name="names" type="xsd:string" minOccurs="1" maxOccurs="1" nillable="true"/>
3592  </sequence>
3593  </complexType>
3594 ~~~
3595 </div>
3596 
3597 An STL container or dynamic array of a union requires wrapping the variant
3598 selector and union member in a struct:
3599 
3600 ~~~{.cpp}
3601  class ns__record
3602  {
3603  public:
3604  std::vector<
3605  struct ns__data // data with a choice of x, n, or s
3606  {
3607  $ int xORnORs; // variant selector with values SOAP_UNION_fieldname
3608  union ns__choice
3609  {
3610  float x;
3611  int n;
3612  char *s;
3613  } u;
3614  }> data; // vector with data
3615  };
3616 ~~~
3617 
3618 and an equivalent definition with a dynamic array instead of a `std::vector`
3619 (you can use this in C with structs):
3620 
3621 ~~~{.cpp}
3622  class ns__record
3623  {
3624  public:
3625  $ int sizeOfdata; // size of dynamic array
3626  struct ns__data // data with a choice of x, n, or s
3627  {
3628  $ int xORnORs; // variant selector with values SOAP_UNION_fieldname
3629  union ns__choice
3630  {
3631  float x;
3632  int n;
3633  char *s;
3634  } u;
3635  } *data; // points to the data array of length sizeOfdata
3636  };
3637 ~~~
3638 
3639 This maps to two complexTypes in the soapcpp2-generated XML schema:
3640 
3641 <div class="alt">
3642 ~~~{.xml}
3643  <complexType name="data">
3644  <choice>
3645  <element name="x" type="xsd:float" minOccurs="1" maxOccurs="1"/>
3646  <element name="n" type="xsd:int" minOccurs="1" maxOccurs="1"/>
3647  <element name="s" type="xsd:string" minOccurs="0" maxOccurs="1" nillable="true"/>
3648  </choice>
3649  </complexType>
3650  <complexType name="record">
3651  <sequence>
3652  <element name="data" type="ns:data" minOccurs="0" maxOccurs="unbounded"/>
3653  </sequence>
3654  </complexType>
3655 ~~~
3656 </div>
3657 
3658 The XML value space consists of a sequence of item elements each wrapped in an
3659 data element:
3660 
3661 <div class="alt">
3662 ~~~{.xml}
3663  <ns:record xmlns:ns="urn:types" ...>
3664  <data>
3665  <n>123</n>
3666  </data>
3667  <data>
3668  <x>3.1</x>
3669  </data>
3670  <data>
3671  <s>hello</s>
3672  </data>
3673  <data>
3674  <s>world</s>
3675  </data>
3676  </ns:record>
3677 ~~~
3678 </div>
3679 
3680 To remove the wrapping data element, simply rename the wrapping struct to
3681 `__ns__data` and the member to `__data` to make this member invisible to the
3682 serializer. The double underscore prefix naming convention is used for the
3683 struct name and member name. Also use a dynamic array instead of a STL
3684 container (so you can also use this approach in C with structs):
3685 
3686 ~~~{.cpp}
3687  class ns__record
3688  {
3689  public:
3690  $ int sizeOfdata; // size of dynamic array
3691  struct __ns__data // contains choice of x, n, or s
3692  {
3693  $ int xORnORs; // variant selector with values SOAP_UNION_fieldname
3694  union ns__choice
3695  {
3696  float x;
3697  int n;
3698  char *s;
3699  } u;
3700  } *__data; // points to the data array of length sizeOfdata
3701  };
3702 ~~~
3703 
3704 This maps to a complexType in the soapcpp2-generated XML schema:
3705 
3706 <div class="alt">
3707 ~~~{.xml}
3708  <complexType name="record">
3709  <sequence minOccurs="0" maxOccurs="unbounded">
3710  <choice>
3711  <element name="x" type="xsd:float" minOccurs="1" maxOccurs="1"/>
3712  <element name="n" type="xsd:int" minOccurs="1" maxOccurs="1"/>
3713  <element name="s" type="xsd:string" minOccurs="0" maxOccurs="1" nillable="true"/>
3714  </choice>
3715  </sequence>
3716  </complexType>
3717 ~~~
3718 </div>
3719 
3720 The XML value space consists of a sequence of <i>`<x>`</i>, <i>`<n>`</i>, and/or <i>`<s>`</i>
3721 elements:
3722 
3723 <div class="alt">
3724 ~~~{.xml}
3725  <ns:record xmlns:ns="urn:types" ...>
3726  <n>123</n>
3727  <x>3.1</x>
3728  <s>hello</s>
3729  <s>world</s>
3730  </ns:record>
3731 ~~~
3732 </div>
3733 
3734 Please note that structs, classes, and unions are unnested by soapcpp2 (as in
3735 the C standard of nested structs and unions). Therefore, the `ns__choice`
3736 union in the `ns__record` class is redeclared at the top level despite its
3737 nesting within the `ns__record` class. This means that you will have to choose
3738 a unique name for each nested struct, class, and union.
3739 
3740 🔝 [Back to table of contents](#)
3741 
3742 ### Tagged void pointer members {#toxsd9-12}
3743 
3744 To serialize data pointed to by `void*` requires run-time type information that
3745 tells the serializer what type of data to serialize by means of a *tagged void
3746 pointer*. This type information is stored in a special type tag member of a
3747 struct/class with the name `__type` or `__typeX`, where `X` can be any name, or
3748 alternatively by an `$int` special member of any name as a type tag:
3749 
3750 ~~~{.cpp}
3751  class ns__record
3752  {
3753  public:
3754  $ int typeOfdata; // type tag with values SOAP_TYPE_T
3755  void *data; // points to some data of type T
3756  };
3757 ~~~
3758 
3759 A type tag member has nonzero values `SOAP_TYPE_T` where `T` is the name of a
3760 struct/class or the name of a primitive type, such as `int`, `std__string` (for
3761 `std::string`), `string` (for `char*`).
3762 
3763 This class maps to a complexType with a sequence in the soapcpp2-generated
3764 XML schema:
3765 
3766 <div class="alt">
3767 ~~~{.xml}
3768  <complexType name="record">
3769  <sequence>
3770  <element name="data" type="xsd:anyType" minOccurs="0" maxOccurs="1"/>
3771  </sequence>
3772  </complexType>
3773 ~~~
3774 </div>
3775 
3776 The XML value space consists of the XML value space of the type with the
3777 addition of an <i>`xsi:type`</i> attribute to the enveloping element:
3778 
3779 <div class="alt">
3780 ~~~{.xml}
3781  <ns:record xmlns:ns="urn:types" ...>
3782  <data xsi:type="xsd:int">123</data>
3783  </ns:record>
3784 ~~~
3785 </div>
3786 
3787 This <i>`xsi:type`</i> attribute is important for the receiving end to distinguish
3788 the type of data to instantiate. The receiver cannot deserialize the data
3789 without an <i>`xsd:type`</i> attribute.
3790 
3791 You can find the `SOAP_TYPE_T` name of each serializable type in the
3792 auto-generated <i>`soapStub.h`</i> file.
3793 
3794 Also all serializable C++ classes have a virtual `int T::soap_type()` member
3795 that returns their `SOAP_TYPE_T` value that you can use.
3796 
3797 When the `void*` pointer is NULL or when `typeOfdata` is zero, the data is not
3798 serialized.
3799 
3800 An STL container or dynamic array of `void*` pointers to <i>`xsd:anyType`</i> data
3801 requires wrapping the type tag and `void*` members in a struct:
3802 
3803 ~~~{.cpp}
3804  class ns__record
3805  {
3806  public:
3807  std::vector<
3808  struct ns__data // data with an xsd:anyType item
3809  {
3810  $ int typeOfitem; // type tag with values SOAP_TYPE_T
3811  void *item; // points to some item of type T
3812  }> data; // vector with data
3813  };
3814 ~~~
3815 
3816 and an equivalent definition with a dynamic array instead of a `std::vector`
3817 (you can use this in C with structs):
3818 
3819 ~~~{.cpp}
3820  class ns__record
3821  {
3822  public:
3823  $ int sizeOfdata; // size of dynamic array
3824  struct ns__data // data with an xsd:anyType item
3825  {
3826  $ int typeOfitem; // type tag with values SOAP_TYPE_T
3827  void *item; // points to some item of type T
3828  } *data; // points to the data array of length sizeOfdata
3829  };
3830 ~~~
3831 
3832 This maps to two complexTypes in the soapcpp2-generated XML schema:
3833 
3834 <div class="alt">
3835 ~~~{.xml}
3836  <complexType name="data">
3837  <sequence>
3838  <element name="item" type="xsd:anyType" minOccurs="1" maxOccurs="1" nillable="true"/>
3839  </sequence>
3840  </complexType>
3841  <complexType name="record">
3842  <sequence>
3843  <element name="data" type="ns:data" minOccurs="0" maxOccurs="unbounded"/>
3844  </sequence>
3845  </complexType>
3846 ~~~
3847 </div>
3848 
3849 The XML value space consists of a sequence of item elements each wrapped in a
3850 data element:
3851 
3852 <div class="alt">
3853 ~~~{.xml}
3854  <ns:record xmlns:ns="urn:types" ...>
3855  <data>
3856  <item xsi:type="xsd:int">123</item>
3857  </data>
3858  <data>
3859  <item xsi:type="xsd:double">3.1</item>
3860  </data>
3861  <data>
3862  <item xsi:type="xsd:string">abc</item>
3863  </data>
3864  </ns:record>
3865 ~~~
3866 </div>
3867 
3868 To remove the wrapping data elements, simply rename the wrapping struct and
3869 member to `__data` to make this member invisible to the serializer with the
3870 double underscore prefix naming convention. Also use a dynamic array instead
3871 of a STL container (you can use this in C with structs):
3872 
3873 ~~~{.cpp}
3874  class ns__record
3875  {
3876  public:
3877  $ int sizeOfdata; // size of dynamic array
3878  struct __data // contains xsd:anyType item
3879  {
3880  $ int typeOfitem; // type tag with values SOAP_TYPE_T
3881  void *item; // points to some item of type T
3882  } *__data; // points to the data array of length sizeOfdata
3883  };
3884 ~~~
3885 
3886 This maps to a complexType in the soapcpp2-generated XML schema:
3887 
3888 <div class="alt">
3889 ~~~{.xml}
3890  <complexType name="record">
3891  <sequence minOccurs="0" maxOccurs="unbounded">
3892  <element name="item" type="xsd:anyType" minOccurs="1" maxOccurs="1"/>
3893  </sequence>
3894  </complexType>
3895 ~~~
3896 </div>
3897 
3898 The XML value space consists of a sequence of data elements:
3899 
3900 <div class="alt">
3901 ~~~{.xml}
3902  <ns:record xmlns:ns="urn:types" ...>
3903  <item xsi:type="xsd:int">123</item>
3904  <item xsi:type="xsd:double">3.1</item>
3905  <item xsi:type="xsd:string">abc</item>
3906  </ns:record>
3907 ~~~
3908 </div>
3909 
3910 Again, please note that structs, classes, and unions are unnested by soapcpp2
3911 (as in the C standard of nested structs and unions). Therefore, the `__data`
3912 struct in the `ns__record` class is redeclared at the top level despite its
3913 nesting within the `ns__record` class. This means that you will have to choose
3914 a unique name for each nested struct, class, and union.
3915 
3916 @see Section [XSD type bindings](#typemap2).
3917 
3918 🔝 [Back to table of contents](#)
3919 
3920 ### Adding get and set methods {#toxsd9-13}
3921 
3922 A public `get` method may be added to a class or struct, which will be
3923 triggered by the deserializer. This method will be invoked right after the
3924 instance is populated by the deserializer. The `get` method can be used to
3925 update or verify deserialized content. It should return `SOAP_OK` or set
3926 `soap::error` to a nonzero error code and return it.
3927 
3928 A public `set` method may be added to a class or struct, which will be
3929 triggered by the serializer. The method will be invoked just before the
3930 instance is serialized. Likewise, the `set` method should return `SOAP_OK` or
3931 set set `soap::error` to a nonzero error code and return it.
3932 
3933 For example, adding a `set` and `get` method to a class declaration:
3934 
3935 ~~~{.cpp}
3936  class ns__record
3937  {
3938  public:
3939  int set(struct soap*); // triggered before serialization
3940  int get(struct soap*); // triggered after deserialization
3941  ...
3942  };
3943 ~~~
3944 
3945 To add these and othe rmethods to classes and structs with wsdl2h and
3946 <i>`typemap.dat`</i>, please see [class/struct member additions](#typemap3).
3947 
3948 🔝 [Back to table of contents](#)
3949 
3950 ### Operations on classes and structs {#toxsd9-14}
3951 
3952 The following functions/macros are generated by soapcpp2 for each type `T`,
3953 which should make it easier to send, receive, and copy XML data in C and in
3954 C++:
3955 
3956 - `int soap_write_T(struct soap*, T*)` writes an instance of `T` to a file via
3957  file descriptor `int soap::sendfd)` or to a stream via `std::ostream
3958  *soap::os` (C++ only) or saves into a NUL-terminated string by setting
3959  `const char **soap::os` to a string pointer to be set (C only). Returns
3960  `SOAP_OK` on success or an error code, also stored in `soap::error`.
3961 
3962 - `int soap_read_T(struct soap*, T*)` reads an instance of `T` from a file via
3963  file descriptor `int soap::recvfd)` or from a stream via `std::istream
3964  *soap::is` (C++ only) or reads from a NUL-termianted string `const char
3965  *soap::is` (C only). Returns `SOAP_OK` on success or an error code, also
3966  stored in `soap::error`.
3967 
3968 - `void soap_default_T(struct soap*, T*)` sets an instance `T` to its default
3969  value, resetting members of a struct to their initial values (for classes we
3970  use method `T::soap_default`, see below). If `T` is a struct that has a
3971  `soap` pointer member to a `::soap` context then this pointer member will be
3972  set to the first argument passed to this function to initialize its `soap`
3973  pointer member.
3974 
3975 - `T * soap_dup_T(struct soap*, T *dst, const T *src)` (requires <b>`soapcpp2 -Ec`</b>)
3976  deep copy `src` into `dst`, replicating all deep cycles and shared pointers
3977  when a managing `soap` context is provided as argument. When `dst` is NULL,
3978  allocates space for `dst` and returns a pointer to the allocated copy. Deep
3979  copy results in a tree when the `soap` context is NULL, but the presence of
3980  deep cycles will lead to non-termination. Use flag `SOAP_XML_TREE` with
3981  managing context to copy into a tree without cycles and pointers to shared
3982  objects. Returns `dst` or allocated copy when `dst` is NULL.
3983 
3984 - `void soap_del_T(const T*)` (requires <b>`soapcpp2 -Ed`</b>) deletes all
3985  heap-allocated members of this object by deep deletion ONLY IF this object
3986  and all of its (deep) members are not managed by a `soap` context AND the deep
3987  structure is a tree (no cycles and co-referenced objects by way of multiple
3988  (non-smart) pointers pointing to the same data). Can be safely used after
3989  `T * soap_dup_T(NULL, NULL, const T*)` to delete the deep copy returned.
3990  Does not delete the object itself.
3991 
3992 When in C++ mode, soapcpp2 tool adds several methods to classes in addition to
3993 adding a default constructor and destructor (when these were not explicitly
3994 declared).
3995 
3996 The public methods added to a class `T`:
3997 
3998 - `virtual int T::soap_type(void)` returns a unique type ID (`SOAP_TYPE_T`).
3999  This numeric ID can be used to distinguish base from derived instances.
4000 
4001 - `virtual void T::soap_default(struct soap*)` sets all data members to
4002  default values. If class `T` has a `soap` pointer member to a `::soap`
4003  context then this pointer member will be set to the argument passed to this
4004  function to initialize its `soap` pointer member.
4005 
4006 - `virtual void T::soap_serialize(struct soap*) const` serializes object to
4007  prepare for SOAP 1.1/1.2 encoded output (or with `SOAP_XML_GRAPH`) by
4008  analyzing its (cyclic) structures.
4009 
4010 - `virtual int T::soap_put(struct soap*, const char *tag, const char *type) const`
4011  emits object in XML, compliant with SOAP 1.1 encoding style, return error
4012  code or `SOAP_OK`. Requires `soap_begin_send(soap)` and
4013  `soap_end_send(soap)`.
4014 
4015 - `virtual int T::soap_out(struct soap*, const char *tag, int id, const char *type) const`
4016  emits object in XML, with tag and optional id attribute and <i>`xsi:type`</i>,
4017  return error code or `SOAP_OK`. Requires `soap_begin_send(soap)` and
4018  `soap_end_send(soap)`.
4019 
4020 - `virtual void * T::soap_get(struct soap*, const char *tag, const char *type)`
4021  Get object from XML, compliant with SOAP 1.1 encoding style, return pointer
4022  to object or NULL on error. Requires `soap_begin_recv(soap)` and
4023  `soap_end_recv(soap)`.
4024 
4025 - `virtual void *soap_in(struct soap*, const char *tag, const char *type)`
4026  Get object from XML, with matching tag and type (NULL matches any tag and
4027  type), return pointer to object or NULL on error. Requires
4028  `soap_begin_recv(soap)` and `soap_end_recv(soap)`
4029 
4030 - `virtual T * T::soap_alloc(void) const` returns a new object of type `T`,
4031  default initialized and not managed by a `soap` context.
4032 
4033 - `virtual T * T::soap_dup(struct soap*) const` (requires <b>`soapcpp2 -Ec`</b>)
4034  returns a duplicate of this object by deep copying, replicating all deep
4035  cycles and shared pointers when a managing `soap` context is provided as
4036  argument. Deep copy is a tree when argument is NULL, but the presence of
4037  deep cycles will lead to non-termination. Use flag `SOAP_XML_TREE` with the
4038  managing context to copy into a tree without cycles and pointers to shared
4039  objects.
4040 
4041 - `virtual void T::soap_del() const` (rquires <b>`soapcpp2 -Ed`</b>) deletes all
4042  heap-allocated members of this object by deep deletion ONLY IF this object
4043  and all of its (deep) members are not managed by a `soap` context AND the deep
4044  structure is a tree (no cycles and co-referenced objects by way of multiple
4045  (non-smart) pointers pointing to the same data). Can be safely used after
4046  `soap_dup(NULL)` to delete the deep copy. Does not delete the object itself.
4047 
4048 Also, there are four variations of `soap_new_T` for
4049 class/struct/template type `T` that soapcpp2 auto-generates to create instances
4050 on a context-managed heap:
4051 
4052 - `T * soap_new_T(struct soap*)` returns a new instance of `T` with default data
4053  member initializations that are set with the soapcpp2 auto-generated `void
4054  T::soap_default(struct soap*)` method), but ONLY IF the soapcpp2
4055  auto-generated default constructor is used that invokes `soap_default()` and
4056  was not replaced by a user-defined default constructor.
4057 
4058 - `T * soap_new_T(struct soap*, int n)` returns an array of `n` new instances of
4059  `T`. Similar to the above, instances are initialized.
4060 
4061 - `T * soap_new_req_T(struct soap*, ...)` returns a new instance of `T` and sets
4062  the required data members to the values specified in `...`. The required data
4063  members are those with nonzero minOccurs, see the subsections on
4064  [(smart) pointer members and their occurrence constraints](#toxsd9-8) and
4065  [container and array members and their occurrence constraints](#toxsd9-9).
4066 
4067 - `T * soap_new_set_T(struct soap*, ...)` returns a new instance of `T` and sets
4068  the public/serializable data members to the values specified in `...`.
4069 
4070 The above functions can be invoked with a NULL `soap` context, but we will be
4071 responsible to use `delete T` to remove this instance from the unmanaged heap.
4072 
4073 The allocation functions return NULL when memory allocation failed.
4074 
4075 🔝 [Back to table of contents](#)
4076 
4077 Special classes and structs {#toxsd10}
4078 ---------------------------
4079 
4080 The following applies to both structs and classes. The examples show classes
4081 in C++. For C, use structs and omit the C++ features. Structs also require
4082 the use of the `struct` keyword, otherwise soapcpp2 will throw a syntax error.
4083 
4084 ### SOAP-encoded arrays {#toxsd10-1}
4085 
4086 A class or struct with the following layout is a one-dimensional SOAP-encoded
4087 array type:
4088 
4089 ~~~{.cpp}
4090  class ArrayOfT
4091  {
4092  public:
4093  T *__ptr; // array pointer
4094  int __size; // array size
4095  };
4096 ~~~
4097 
4098 where `T` is the array element type. A multidimensional SOAP Array is:
4099 
4100 ~~~{.cpp}
4101  class ArrayOfT
4102  {
4103  public:
4104  T *__ptr; // array pointer
4105  int __size[N]; // array size of each dimension
4106  };
4107 ~~~
4108 
4109 where `N` is the constant number of dimensions. The pointer points to an array
4110 of `__size[0]*__size[1]* ... * __size[N-1]` elements.
4111 
4112 This maps to a complexType restriction of SOAP-ENC:Array in the
4113 soapcpp2-generated XML schema:
4114 
4115 <div class="alt">
4116 ~~~{.xml}
4117  <complexType name="ArrayOfT">
4118  <complexContent>
4119  <restriction base="SOAP-ENC:Array">
4120  <sequence>
4121  <element name="item" type="T" minOccurs="0" maxOccurs="unbounded" nillable="true"/>
4122  </sequence>
4123  <attribute ref="SOAP-ENC:arrayType" WSDL:arrayType="ArrayOfT[]"/>
4124  </restriction>
4125  </complexContent>
4126  </complexType>
4127 ~~~
4128 </div>
4129 
4130 The name of the class can be arbitrary. We often use `ArrayOfT` without a
4131 prefix to distinguish arrays from other classes and structs.
4132 
4133 With SOAP 1.1 encoding, an optional offset member can be added that controls
4134 the start of the index range for each dimension:
4135 
4136 ~~~{.cpp}
4137  class ArrayOfT
4138  {
4139  public:
4140  T *__ptr; // array pointer
4141  int __size[N]; // array size of each dimension
4142  int __offset[N]; // array offsets to start each dimension
4143  };
4144 ~~~
4145 
4146 For example, we can define a matrix of floats as follows:
4147 
4148 ~~~{.cpp}
4149  class Matrix
4150  {
4151  public:
4152  double *__ptr;
4153  int __size[2];
4154  };
4155 ~~~
4156 
4157 The following code populates the matrix and serializes it in XML:
4158 
4159 ~~~{.cpp}
4160  soap *soap = soap_new1(SOAP_XML_INDENT);
4161  Matrix A;
4162  double a[6] = { 1, 2, 3, 4, 5, 6 };
4163  A.__ptr = a;
4164  A.__size[0] = 2;
4165  A.__size[1] = 3;
4166  soap_write_Matrix(soap, &A);
4167 ~~~
4168 
4169 Matrix A is serialized as an array with 2x3 values:
4170 
4171 <div class="alt">
4172 ~~~{.xml}
4173  <SOAP-ENC:Array SOAP-ENC:arrayType="xsd:double[2,3]" ...>
4174  <item>1</item>
4175  <item>2</item>
4176  <item>3</item>
4177  <item>4</item>
4178  <item>5</item>
4179  <item>6</item>
4180  </SOAP-ENC:Array>
4181 ~~~
4182 </div>
4183 
4184 🔝 [Back to table of contents](#)
4185 
4186 ### XSD hexBinary and base64Binary types {#toxsd10-2}
4187 
4188 A special case of a one-dimensional array is used to define <i>`xsd:hexBinary`</i> and
4189 <i>`xsd:base64Binary`</i> types when the pointer type is `unsigned char`:
4190 
4191 ~~~{.cpp}
4192  class xsd__hexBinary
4193  {
4194  public:
4195  unsigned char *__ptr; // points to raw binary data
4196  int __size; // size of data
4197  };
4198 ~~~
4199 
4200 and
4201 
4202 ~~~{.cpp}
4203  class xsd__base64Binary
4204  {
4205  public:
4206  unsigned char *__ptr; // points to raw binary data
4207  int __size; // size of data
4208  };
4209 ~~~
4210 
4211 To create a new binary type, use either one of the following three forms that
4212 declare a new `ns__binary` type that is a <i>`simpleType`</i> restriction of
4213 <i>`xsd:base64Binary`</i>:
4214 
4215 ~~~{.cpp}
4216  typedef xsd__base64Binary ns__binary;
4217 ~~~
4218 ~~~{.cpp}
4219  class ns__binary : public xsd__base64Binary
4220  {
4221  ... // attribute members (@) and class methods
4222  };
4223 ~~~
4224 ~~~{.cpp}
4225  class ns__binary
4226  {
4227  public:
4228  unsigned char *__ptr; // points to raw binary data
4229  int __size; // size of data
4230  ... // attribute members (@) and class methods (optional)
4231  };
4232 ~~~
4233 
4234 Here, `xsd__base64Binary` is reused in the first two cases, where
4235 `xsd__base64Binary` is declared as shown above.
4236 
4237 @see [DIME/MIME/MTOM attachment binary types](#toxsd10-3)
4238 
4239 🔝 [Back to table of contents](#)
4240 
4241 ### DIME/MIME/MTOM attachment binary types {#toxsd10-3}
4242 
4243 A class or struct with a binary content layout can be extended to support
4244 attachments. The following struct or class type can be used as DIME, MIME, and
4245 MTOM attachment and also be used for <i>`xsd:base64Binary`</i> type values:
4246 
4247 ~~~{.cpp}
4248  class xsd__base64Binary
4249  {
4250  public:
4251  unsigned char *__ptr; // points to raw binary data
4252  int __size; // size of data
4253  char *id; // NULL to generate an id, or set to a unique UUID
4254  char *type; // MIME type of the data
4255  char *options; // optional description of MIME attachment
4256  };
4257 ~~~
4258 
4259 When the `id`, `type`, or `options` members are non-NULL, an attachment will be
4260 used instead of base64 XML content. DIME attachments are the default. To
4261 switch to MIME use the `SOAP_ENC_MIME` context flag. To switch to MTOM use the
4262 `SOAP_ENC_MTOM` context flag.
4263 
4264 MTOM is typically used with XOP <i>`<xop:Include>`</i> elements, which is
4265 preferred and declared as follows:
4266 
4267 ~~~{.cpp}
4268  //gsoap xop schema import: http://www.w3.org/2004/08/xop/include
4269  class _xop__Include
4270  {
4271  public:
4272  unsigned char *__ptr; // points to raw binary data
4273  int __size; // size of data
4274  char *id; // NULL to generate an id, or set to a unique UUID
4275  char *type; // MIME type of the data
4276  char *options; // optional description of MIME attachment
4277  };
4278 ~~~
4279 
4280 Attachments are beyond the scope of this article. See the
4281 [gSOAP user guide.](../../guide/html/index.html) for more details.
4282 
4283 🔝 [Back to table of contents](#)
4284 
4285 ### Wrapper class/struct with simpleContent {#toxsd10-4}
4286 
4287 A class or struct with the following layout is a complexType that wraps
4288 simpleContent:
4289 
4290 ~~~{.cpp}
4291  class ns__simple
4292  {
4293  public:
4294  T __item; // primitive type for the simpleContent
4295  ... // attribute members (@) and class methods (optional)
4296  };
4297 ~~~
4298 
4299 The type `T` is a primitive type (`bool`, `enum`, `time_t`, numeric and string
4300 types), `xsd__hexBinary`, `xsd__base64Binary`, and custom serializers, such as
4301 `xsd__dateTime`.
4302 
4303 This maps to a complexType with simpleContent in the soapcpp2-generated XML
4304 schema:
4305 
4306 <div class="alt">
4307 ~~~{.xml}
4308  <complexType name="simple">
4309  <simpleContent>
4310  <extension base="T"/>
4311  </simpleContent>
4312  </complexType>
4313 ~~~
4314 </div>
4315 
4316 A wrapper class/struct may include any number of members that are declared as
4317 attributes with `@`, which should be placed after the `__item` member.
4318 
4319 🔝 [Back to table of contents](#)
4320 
4321 ### DOM anyType and anyAttribute {#toxsd10-5}
4322 
4323 Use of a DOM is optional and enabled by `#import "dom.h"` to use the DOM
4324 `xsd__anyType` element node and `xsd__anyAttribute` attribute node:
4325 
4326 ~~~{.cpp}
4327  #import "dom.h"
4328 
4329  class ns__record
4330  {
4331  public:
4332  @ xsd__anyAttribute attributes; // optional DOM attributes
4333  xsd__anyType *name; // optional DOM element (pointer means minOccurs=0)
4334  xsd__anyType address; // required DOM element (minOccurs=1)
4335  xsd__anyType email 0; // optional DOM element (minOccurs=0)
4336  ... // other members
4337  };
4338 ~~~
4339 
4340 where `name` contains XML stored in a DOM node set and `attributes` is a list
4341 of all visibly rendered attributes. The name `attributes` is arbitrary and any
4342 name will suffice.
4343 
4344 You should place the `xsd__anyType` members at the end of the struct or class.
4345 This ensures that the DOM members are populated last as a "catch all". A
4346 member name starting with double underscore is a wildcard member. These
4347 members are placed at the end of a struct or class automatically by soapcpp2.
4348 
4349 An `#import "dom.h"` import is automatically added by <b>`wsdl2h -d`</b> with
4350 option <b>`-d`</b> to bind <i>`xsd:anyType`</i> to DOM nodes, and also to
4351 populate <i>`xsd:any`</i>, <i>`xsd:anyAttribute`</i> and <i>`xsd:mixed`</i> XML
4352 content:
4353 
4354 ~~~{.cpp}
4355  #import "dom.h"
4356 
4357  class ns__record
4358  {
4359  public:
4360  @ xsd__anyAttribute __anyAttribute; // optional DOM attributes
4361  std::vector<xsd__anyType> __any 0; // optional DOM elements (minOccurs=0)
4362  xsd__anyType __mixed 0; // optional mixed content (minOccurs=0)
4363  ... // other members
4364  };
4365 ~~~
4366 
4367 where the members prefixed with `__` are "invisible" to the XML parser, meaning
4368 that these members are not bound to XML tag names.
4369 
4370 In C you can use a dynamic arrary instead of `std::vector`:
4371 
4372 ~~~{.cpp}
4373  #import "dom.h"
4374 
4375  struct ns__record
4376  {
4377  @ xsd__anyAttribute __anyAttribute; // optional DOM attributes
4378  $ int __sizeOfany; // size of the array
4379  xsd__anyType *__any; // optional DOM elements (pointer means minOccurs=0)
4380  xsd__anyType __mixed 0; // optional mixed content (minOccurs=0)
4381  ... // other members
4382  };
4383 ~~~
4384 
4385 Classes can inherit DOM, which enables full use of polymorphism with one base
4386 DOM class:
4387 
4388 ~~~{.cpp}
4389  #import "dom.h"
4390 
4391  class ns__record : public xsd__anyType
4392  {
4393  public:
4394  std::vector<xsd__anyType*> array; // array of objects of any class
4395  ... // other members
4396  };
4397 ~~~
4398 
4399 This permits an `xsd__anyType` pointer to refer to a derived class such as
4400 `ns__record`, which will be serialized with an <i>`xsi:type`</i> attribute that is
4401 set to "ns:record". The <i>`xsi:type`</i> attributes add the necessary type information
4402 to distinguish the XML content from the DOM base type. This is important for
4403 the receiving end: without <i>`xsd:type`</i> attributes with type names, only base DOM
4404 objects are recognized and instantiated.
4405 
4406 Because C lacks object-oriented programming concepts such as class inheritance
4407 and polymorphism, you should consider using [derived types in C and C++](#toxsd9-1-1).
4408 
4409 An alternative is to use the special [tagged void pointer members](#toxsd9-12)
4410 to serialize data pointed to by a `void*` member, which can be any serializable
4411 type, such as derived types. This approach uses <i>`xsi:type`</i> attributes
4412 to identify the type of value serialized.
4413 
4414 To ensure that wsdl2h generates pointer-based `xsd__anyType` DOM nodes with
4415 <b>`wsdl2h -d`</b> using option <b>`-d`</b> for <i>`xsd:any`</i>, add the
4416 following line to <i>`typemap.dat`</i>:
4417 
4418  xsd__any = | xsd__anyType*
4419 
4420 This lets wsdl2h produce class/struct members and containers with
4421 `xsd__anyType*` for <i>`xsd:any`</i> instead of `xsd__anyType`. To just force all
4422 <i>`xsd:anyType`</i> uses to be pointer-based, declare in <i>`typemap.dat`</i>:
4423 
4424  xsd__anyType = | xsd__anyType*
4425 
4426 If you use <b>`wsdl2h -d -p`</b> using options <b>`-d`</b> and <b>`-p`</b> then
4427 every class will inherit DOM as shown above. Without option `-d`, an
4428 `xsd__anyType` type is generated to serve as the root type in the type
4429 hierarchy:
4430 
4431 ~~~{.cpp}
4432  class xsd__anyType { _XML __item; struct soap *soap; };
4433 
4434  class ns__record : public xsd__anyType
4435  {
4436  ...
4437  };
4438 ~~~
4439 
4440 where the `_XML __item` member holds any XML content as a literal XML string.
4441 
4442 To use the DOM API, compile <i>`dom.c`</i> (or <i>`dom.cpp`</i> for C++), or
4443 link the gSOAP library with <b>`-lgsoapssl`</b> (or <b>`-lgsoapssl++`</b> for C++).
4444 
4445 @see Documentation of [XML DOM and XPath](http://www.genivia.com/doc/dom/html)
4446 for more details.
4447 
4448 🔝 [Back to table of contents](#)
4449 
4450 Directives {#directives}
4451 ==========
4452 
4453 You can use `//gsoap` directives in the interface header file with the data
4454 binding interface for soapcpp2. These directives are used to configure the
4455 code generated by soapcpp2 by declaring various. properties of Web services
4456 and XML schemas. When using the wsdl2h tool, you will notice that wsdl2h
4457 generates directives automatically based on the WSDL and XSD input.
4458 
4459 Service directives are applicable to service and operations described by WSDL.
4460 Schema directives are applicable to types, elements, and attributes defined by
4461 XML schemas.
4462 
4463 🔝 [Back to table of contents](#)
4464 
4465 Service directives {#directives-1}
4466 ------------------
4467 
4468 A service directive must start at a new line and is of the form:
4469 
4470 ~~~{.cpp}
4471  //gsoap <prefix> service <property>: <value>
4472 ~~~
4473 
4474 where `<prefix>` is the XML namespace prefix of a service binding. The
4475 `<property>` and `<value>` fields are one of the following:
4476 
4477 property | value
4478 --------------- | -----
4479 `name` | name of the service, optionally followed by text describing the service
4480 `namespace` | URI of the WSDL targetNamespace
4481 `documentation` | text describing the service (see also the `name` property), multiple permitted
4482 `doc` | an alias for the `documentation` property
4483 `style` | `document` (default) SOAP messaging style or `rpc` for SOAP RPC
4484 `encoding` | `literal` (default), `encoded` for SOAP encoding, or a custom URI
4485 `protocol` | specifies SOAP or REST, see below
4486 `port` | URL of the service endpoint, usually an http or https address, to use in the WSDL definitions/service/port/address/\@location
4487 `location` | an alias for the `port` property
4488 `endpoint` | an alias for the `port` property
4489 `transport` | URI declaration of the transport, usually `http://schemas.xmlsoap.org/soap/http`
4490 `definitions` | name of the WSDL definitions/\@name
4491 `type` | name of the WSDL definitions/portType/\@name (WSDL2.0 interface/\@name)
4492 `portType` | an alias for the `type` property (`portType` follows SOAP 1.1 naming conventions)
4493 `interface` | an alias for the `type` property (`interface` follows SOAP 1.2 naming conventions)
4494 `binding` | name of the WSDL definitions/binding/\@name
4495 `portName` | name of the WSDL definitions/service/port/\@name
4496 `executable` | name of the "executable" to use in the WSDL definitions/service/port/address/\@location
4497 
4498 The service `name` and `namespace` properties are required in order to generate
4499 a valid WSDL with soapcpp2. The other properties are optional.
4500 
4501 The `style` and `encoding` property defaults are changed with
4502 <b>`soapcpp2 -e`</b> option <b>`-e`</b> to `rpc` and `encoded`, respectively.
4503 
4504 The `protocol` property is `SOAP` by default (SOAP 1.1). Protocol property
4505 values are:
4506 
4507 protocol value | description
4508 -------------- | -----------
4509 `SOAP` | SOAP transport, supporting both SOAP 1.1 and 1.2
4510 `SOAP1.1` | SOAP 1.1 transport (same as `soapcpp2 -1`)
4511 `SOAP1.2` | SOAP 1.2 transport (same as `soapcpp2 -2`)
4512 `SOAP-GET` | one-way SOAP 1.1 or 1.2 with HTTP GET
4513 `SOAP1.1-GET` | one-way SOAP 1.1 with HTTP GET
4514 `SOAP1.2-GET` | one-way SOAP 1.2 with HTTP GET
4515 `HTTP` | non-SOAP REST protocol with HTTP POST
4516 `POST` | non-SOAP REST protocol with HTTP POST
4517 `GET` | non-SOAP REST protocol with HTTP GET
4518 `PUT` | non-SOAP REST protocol with HTTP PUT
4519 `DELETE` | non-SOAP REST protocol with HTTP DELETE
4520 
4521 You can bind service operations to the WSDL namespace of a service by using the
4522 namespace prefix as part of the identifier name of the function that defines
4523 the service operation:
4524 
4525 ~~~{.cpp}
4526  int prefix__func(arg1, arg2, ..., argn, result);
4527 ~~~
4528 
4529 You can override the `port` endpoint URL at runtime in the auto-generated
4530 `soap_call_prefix__func` service call (C/C++ client side) and in the C++ proxy
4531 class service call.
4532 
4533 🔝 [Back to table of contents](#)
4534 
4535 Service method directives {#directives-2}
4536 -------------------------
4537 
4538 Service properties are applicable to a service and to all of its operations.
4539 Service method directives are specifically applicable to a service operation.
4540 
4541 A service method directive is of the form:
4542 
4543 ~~~{.cpp}
4544  //gsoap <prefix> service method-<property>: <method> <value>
4545 ~~~
4546 
4547 where `<prefix>` is the XML namespace prefix of a service binding and
4548 `<method>` is the unqualified name of a service operation. The `<property>`
4549 and `<value>` fields are one of the following:
4550 
4551 method property | value
4552 --------------------------- | -----
4553 `method-documentation` | text describing the service operation
4554 `method` | an alias for the `method-documentation` property
4555 `method-action` | `""` or URI SOAPAction HTTP header, or URL query string for REST protocols
4556 `method-input-action` | `""` or URI SOAPAction HTTP header of service request messages
4557 `method-output-action` | `""` or URI SOAPAction HTTP header of service response messages
4558 `method-fault-action` | `""` or URI SOAPAction HTTP header of service fault messages
4559 `method-header-part` | member name of the `SOAP_ENV__Header` struct used in SOAP Header
4560 `method-input-header-part` | member name of the `SOAP_ENV__Header` struct used in SOAP Headers of requests
4561 `method-output-header-part` | member name of the `SOAP_ENV__Header` struct used in SOAP Headers of responses
4562 `method-fault` | type name of a struct or class member used in `SOAP_ENV__Details` struct
4563 `method-mime-type` | REST content type or SOAP MIME attachment content type(s)
4564 `method-input-mime-type` | REST content type or SOAP MIME attachment content type(s) of request message
4565 `method-output-mime-type` | REST content type or SOAP MIME attachment content type(s) of response message
4566 `method-style` | `document` or `rpc`
4567 `method-encoding` | `literal`, `encoded`, or a custom URI for encodingStyle of messages
4568 `method-response-encoding` | `literal`, `encoded`, or a custom URI for encodingStyle of response messages
4569 `method-protocol` | SOAP or REST, see [service directives](#directives-1)
4570 
4571 The `method-header-part` properties can be repeated for a service operation to
4572 declare multiple SOAP Header parts that the service operation requires. You
4573 can use `method-input-header-part` and `method-output-header-part` to
4574 differentiate between request and response messages.
4575 
4576 The `method-fault` property can be repeated for a service operation to declare
4577 multiple faults that the service operation may return.
4578 
4579 The `method-action` property serves two purposes:
4580 
4581 -# To set the SOAPAction header for SOAP protocols, i.e. sets the
4582  definitions/binding/operation/SOAP:operation/\@soapAction.
4583 
4584 -# To set the URL query string for endpoints with REST protocols, i.e. sets the
4585  definitions/binding/operation/HTTP:operation/\@location, which specifies
4586  a URL query string (starts with a `?`) to complete the service endpoint URL
4587  or extends the endpoint URL with a local path (starts with a `/`).
4588 
4589 Use `method-input-action` and `method-output-action` to differentiate the
4590 SOAPAction between SOAP request and response messages.
4591 
4592 You can always override the port endpoint URL and action values at runtime in
4593 the auto-generated `soap_call_prefix__func` service call (C/C++ client side)
4594 and in the auto-generated C++ proxy class service calls. A runtime NULL
4595 endpoint URL and/or action uses the defaults set by these directives.
4596 
4597 The `method-mime-type` property serves two purposes:
4598 
4599 -# To set the type of MIME/MTOM attachments used with SOAP protocols. Multiple
4600  attachment types can be declared for a SOAP service operation, i.e. adds
4601  definitions/binding/operation/input/MIME:multipartRelated/MIME:part/MIME:content/\@type
4602  for each type specified.
4603 
4604 -# To set the MIME type of a REST operation. This replaces XML declared in
4605  WSDL by definitions/binding/operation/(input|output)/MIME:mimeXml with
4606  MIME:content/\@type. Use `application/x-www-form-urlencoded` with REST POST
4607  and PUT protocols to send encoded form data automatically instead of XML.
4608  Only primitive type values can be transmitted with form data, such as
4609  numbers and strings, i.e. only types that are legal to use as
4610  [attributes members](#toxsd9-5).
4611 
4612 Use `method-input-mime-type` and `method-output-mime-type` to differentiate the
4613 attachment types between request and response messages.
4614 
4615 🔝 [Back to table of contents](#)
4616 
4617 Schema directives {#directives-3}
4618 -----------------
4619 
4620 A schema directive is of the form:
4621 
4622 ~~~{.cpp}
4623  //gsoap <prefix> schema <property>: <value>
4624 ~~~
4625 
4626 where `<prefix>` is the XML namespace prefix of a schema. The `<property>` and
4627 `<value>` fields are one of the following:
4628 
4629 property | value
4630 --------------- | -----
4631 `namespace` | URI of the XSD targetNamespace
4632 `namespace2` | alternate URI pattern for the XSD namespace (i.e. URI is also accepted by the XML parser)
4633 `import` | URI of an imported namespace, as an alternative or in addition to `namespace`, adds `xsd:import` to the generated WSDL and XSD files
4634 `form` | `unqualified` (default) or `qualified` local element and attribute form defaults
4635 `elementForm` | `unqualified` (default) or `qualified` local element form default
4636 `attributeForm` | `unqualified` (default) or `qualified` local attribute form default
4637 `typed` | `no` (default) or `yes` for serializers to add `xsi:type` attributes to XML
4638 
4639 To learn more about the local form defaults, see [qualified and unqualified members.](#toxsd9-6)
4640 
4641 The `namespace2` URI is a pattern with `*` matching any sequence of characters
4642 and `-` matching any character. This pattern instructs the XML parser and validator
4643 to also accept the URI pattern as a valid namespace for the specified `<prefix>`.
4644 
4645 The `typed` property is implicitly `yes` when <b>`soapcpp2 -t`</b> option <b>`-t`</b> is used.
4646 
4647 🔝 [Back to table of contents](#)
4648 
4649 Schema type directives {#directives-4}
4650 ----------------------
4651 
4652 A schema type directive is of the form:
4653 
4654 ~~~{.cpp}
4655  //gsoap <prefix> schema type-<property>: <name> <value>
4656  //gsoap <prefix> schema type-<property>: <name>::<member> <value>
4657 ~~~
4658 
4659 where `<prefix>` is the XML namespace prefix of a schema and `<name>` is an
4660 unqualified name of a C/C++ type, and the optional `<member>` is a class/struct
4661 members or enum constant.
4662 
4663 You can describe a type with one of the following:
4664 
4665 type property | value
4666 -------------------- | -----
4667 `type-documentation` | text describing the schema type
4668 `type` | an alias for the `type-documentation` property
4669 
4670 For example, you can add a description to an enumeration:
4671 
4672 ~~~{.cpp}
4673  //gsoap ns schema type: Vowels The letters A, E, I, O, U, and sometimes Y
4674  //gsoap ns schema type: Vowels::Y A vowel, sometimes
4675  enum class ns__Vowels : char { A = 'A', E = 'E', I = 'I', O = 'O', U = 'U', Y = 'Y' };
4676 ~~~
4677 
4678 This documented enumeration maps to a simpleType restriction of <i>`xsd:string`</i> in
4679 the soapcpp2-generated schema:
4680 
4681 <div class="alt">
4682 ~~~{.xml}
4683  <simpleType name="Vowels">
4684  <annotation>
4685  <documentation>The letters A, E, I, O, U, and sometimes Y</documentation>
4686  </annotation>
4687  <restriction base="xsd:string">
4688  <enumeration value="A"/>
4689  <enumeration value="E"/>
4690  <enumeration value="I"/>
4691  <enumeration value="O"/>
4692  <enumeration value="U"/>
4693  <enumeration value="Y">
4694  <annotation>
4695  <documentation>A vowel, sometimes</documentation>
4696  </annotation>
4697  <enumeration/>
4698  </restriction>
4699  </simpleType>
4700 ~~~
4701 </div>
4702 
4703 🔝 [Back to table of contents](#)
4704 
4705 Serialization rules {#rules}
4706 ===================
4707 
4708 A presentation on XML data bindings is not complete without discussing the
4709 serialization rules and options that put your data in XML on the wire or store
4710 it a file or buffer.
4711 
4712 There are several options to choose from to serialize data in XML. The choice
4713 depends on the use of the SOAP protocol or if SOAP is not required. The wsdl2h
4714 tool automates this for you by taking the WSDL transport bindings into account
4715 when generating the service functions in C and C++ that use SOAP or REST.
4716 
4717 The gSOAP tools are not limited to SOAP. The tools implement generic XML data
4718 bindings for SOAP, REST, and other uses of XML. So you can read and write XML
4719 using the serializing [operations on classes and structs](#toxsd9-14).
4720 
4721 The following sections briefly explain the serialization rules with respect to
4722 the SOAP protocol for XML Web services. A basic understanding of the SOAP
4723 protocol is useful when developing client and server applications that must
4724 interoperate with other SOAP applications.
4725 
4726 SOAP/REST Web service client and service operations are represented as
4727 functions in your interface header file with the data binding interface for
4728 soapcpp2. The soapcpp2 tool will translate these function to client-side
4729 service invocation calls and server-side service operation dispatchers.
4730 
4731 A discussion of SOAP clients and servers is beyond the scope of this article.
4732 However, the SOAP options discussed here also apply to SOAP client and server
4733 development.
4734 
4735 🔝 [Back to table of contents](#)
4736 
4737 SOAP document versus rpc style {#doc-rpc}
4738 ------------------------------
4739 
4740 The `wsdl:binding/soap:binding/@style` attribute in the <i>`<wsdl:binding>`</i>
4741 section of a WSDL is either "document" or "rpc". The "rpc" style refers to
4742 SOAP RPC (Remote Procedure Call), which is more restrictive than the "document"
4743 style by requiring one XML element in the SOAP Body to act as the procedure
4744 name with XML subelements as its parameters.
4745 
4746 For example, the following directives in the interface header file for soapcpp2
4747 declare that `DBupdate` is a SOAP RPC encoding service method:
4748 
4749 ~~~{.cpp}
4750  //gsoap ns service namespace: urn:DB
4751  //gsoap ns service method-protocol: DBupdate SOAP
4752  //gsoap ns service method-style: DBupdate rpc
4753  int ns__DBupdate(...);
4754 ~~~
4755 
4756 The XML payload has a SOAP envelope, optional SOAP header, and a SOAP body with
4757 one element representing the operation with the parameters as subelements:
4758 
4759 <div class="alt">
4760 ~~~{.xml}
4761  <SOAP-ENV:Envelope
4762  xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"
4763  xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/"
4764  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4765  xmlns:xsd="http://www.w3.org/2001/XMLSchema"
4766  xmlsn:ns="urn:DB">
4767  <SOAP-ENV:Body>
4768  <ns:DBupdate>
4769  ...
4770  </ns:DBupdate>
4771  </SOAP-ENV:Body>
4772  </SOAP-ENV:Envelope>
4773 ~~~
4774 </div>
4775 
4776 The "document" style puts no restrictions on the SOAP Body content. However, we
4777 recommend that the first element's tag name in the SOAP Body should be unique
4778 to each type of operation, so that the receiver can dispatch the operation
4779 based on this element's tag name. Alternatively, the HTTP URL path can be used
4780 to specify the operation, or the HTTP action header can be used to dispatch
4781 operations automatically on the server side (soapcpp2 options -a and -A).
4782 
4783 🔝 [Back to table of contents](#)
4784 
4785 SOAP literal versus encoding {#lit-enc}
4786 ----------------------------
4787 
4788 The `wsdl:operation/soap:body/@use` attribute in the <i>`<wsdl:binding>`</i> section
4789 of a WSDL is either "literal" or "encoded". The "encoded" use refers to the
4790 SOAP encoding rules that support id-ref multi-referenced elements to serialize
4791 data as graphs.
4792 
4793 SOAP encoding is very useful if the data internally forms a graph (including
4794 cycles) and we want the graph to be serialized in XML in a format that ensures
4795 that its structure is preserved. In that case, SOAP 1.2 encoding is the best
4796 option.
4797 
4798 SOAP encoding also adds encoding rules for [SOAP arrays](#toxsd10) to serialize
4799 multi-dimensional arrays. The use of XML attributes to exchange XML data in
4800 SOAP encoding is not permitted. The only attributes permitted are the standard
4801 XSD attributes, SOAP encoding attributes (such as for arrays), and id-ref.
4802 
4803 For example, the following directives in the interface header file for soapcpp2
4804 declare that `DBupdate` is a SOAP RPC encoding service method:
4805 
4806 ~~~{.cpp}
4807  //gsoap ns service namespace: urn:DB
4808  //gsoap ns service method-protocol: DBupdate SOAP
4809  //gsoap ns service method-style: DBupdate rpc
4810  //gsoap ns service method-encoding: DBupdate encoded
4811  int ns__DBupdate(...);
4812 ~~~
4813 
4814 The XML payload has a SOAP envelope, optional SOAP header, and a SOAP body with
4815 an encodingStyle attribute for SOAP 1.1 encoding and an element representing the
4816 operation with parameters that are SOAP 1.1 encoded:
4817 
4818 <div class="alt">
4819 ~~~{.xml}
4820  <SOAP-ENV:Envelope
4821  xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"
4822  xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/"
4823  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4824  xmlns:xsd="http://www.w3.org/2001/XMLSchema"
4825  xmlsn:ns="urn:DB">
4826  <SOAP-ENV:Body SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/">
4827  <ns:DBupdate>
4828  <records SOAP-ENC:arrayType="ns:record[3]">
4829  <item>
4830  <name href="#_1"/>
4831  <SSN>1234567890</SSN>
4832  </item>
4833  <item>
4834  <name>Jane</name>
4835  <SSN>1987654320</SSN>
4836  </item>
4837  <item>
4838  <name href="#_1"/>
4839  <SSN>2345678901</SSN>
4840  </item>
4841  </records>
4842  </ns:DBupdate>
4843  <id id="_1" xsi:type="xsd:string">Joe</id>
4844  </SOAP-ENV:Body>
4845  </SOAP-ENV:Envelope>
4846 ~~~
4847 </div>
4848 
4849 In the XML fragment shown above the name "Joe" is shared by two records and the
4850 string is referenced by SOAP 1.1 href and id attributes.
4851 
4852 While the soapcpp-generated serializers only introduce multi-referenced
4853 elements in the payload when they are actually multi-referenced in the data
4854 graph, other SOAP applications may render multi-referenced elements more
4855 aggressively. The example could also be rendered as:
4856 
4857 <div class="alt">
4858 ~~~{.xml}
4859  <SOAP-ENV:Envelope
4860  xmlns:SOAP-ENV="http://schemas.xmlsoap.org/soap/envelope/"
4861  xmlns:SOAP-ENC="http://schemas.xmlsoap.org/soap/encoding/"
4862  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4863  xmlns:xsd="http://www.w3.org/2001/XMLSchema"
4864  xmlsn:ns="urn:DB">
4865  <SOAP-ENV:Body SOAP-ENV:encodingStyle="http://schemas.xmlsoap.org/soap/encoding/">
4866  <ns:DBupdate>
4867  <records SOAP-ENC:arrayType="ns:record[3]">
4868  <item href="#id1"/>
4869  <item href="#id2"/>
4870  <item href="#id3"/>
4871  </records>
4872  </ns:DBupdate>
4873  <id id="id1" xsi:type="ns:record">
4874  <name href="#id4"/>
4875  <SSN>1234567890</SSN>
4876  </id>
4877  <id id="id2" xsi:type="ns:record">
4878  <name href="#id5"/>
4879  <SSN>1987654320</SSN>
4880  </id>
4881  <id id="id3" xsi:type="ns:record">
4882  <name href="#id4"/>
4883  <SSN>2345678901</SSN>
4884  </id>
4885  <id id="id4" xsi:type="xsd:string">Joe</id>
4886  <id id="id5" xsi:type="xsd:string">Jane</id>
4887  </SOAP-ENV:Body>
4888  </SOAP-ENV:Envelope>
4889 ~~~
4890 </div>
4891 
4892 SOAP 1.2 encoding is cleaner and produces more accurate XML encodings of data
4893 graphs by setting the id attribute on the element that is referenced:
4894 
4895 <div class="alt">
4896 ~~~{.xml}
4897  <SOAP-ENV:Envelope
4898  xmlns:SOAP-ENV="http://www.w3.org/2003/05/soap-envelope"
4899  xmlns:SOAP-ENC="http://www.w3.org/2003/05/soap-encoding"
4900  xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4901  xmlns:xsd="http://www.w3.org/2001/XMLSchema"
4902  xmlsn:ns="urn:DB">
4903  <SOAP-ENV:Body>
4904  <ns:DBupdate SOAP-ENV:encodingStyle="http://www.w3.org/2003/05/soap-encoding">
4905  <records SOAP-ENC:itemType="ns:record" SOAP-ENC:arraySize="3">
4906  <item>
4907  <name SOAP-ENC:id="_1">Joe</name>
4908  <SSN>1234567890</SSN>
4909  </item>
4910  <item>
4911  <name>Jane</name>
4912  <SSN>1987654320</SSN>
4913  </item>
4914  <item>
4915  <name SOAP-ENC:ref="_1"/>
4916  <SSN>2345678901</SSN>
4917  </item>
4918  </records>
4919  </ns:DBupdate>
4920  </SOAP-ENV:Body>
4921  </SOAP-ENV:Envelope>
4922 ~~~
4923 </div>
4924 
4925 @note Some SOAP 1.2 applications consider the namespace `SOAP-ENC` of
4926 <i>`SOAP-ENC:id`</i> and <i>`SOAP-ENC:ref`</i> optional. With gSOAP, the SOAP
4927 1.2 encoding serialization follows the 2007 standard, while accepting
4928 unqualified id and ref attributes.
4929 
4930 To remove all rendered id-ref multi-referenced elements, use the
4931 `SOAP_XML_TREE` flag to initialize the `soap` context.
4932 
4933 Some XSD validation rules are turned off with SOAP encoding, because of the
4934 presence of additional attributes, such as id and ref/href, SOAP arrays with
4935 arbitrary element tags for array elements, and the occurrence of additional
4936 multi-ref elements in the SOAP 1.1 Body.
4937 
4938 The use of "literal" puts no restrictions on the XML in the SOAP Body. Full
4939 XSD validation is possible, which can be enabled with the `SOAP_XML_STRICT`
4940 flag to initialize the `soap` context. However, data graphs will be
4941 serialized as trees and cycles in the data will be cut from the XML rendition.
4942 
4943 🔝 [Back to table of contents](#)
4944 
4945 SOAP 1.1 versus SOAP 1.2 {#soap}
4946 ------------------------
4947 
4948 There are two SOAP protocol versions: 1.1 and 1.2. The gSOAP tools can switch
4949 between the two versions seamlessly. You can declare the default SOAP version
4950 for a service operation as follows:
4951 
4952 ~~~{.cpp}
4953  //gsoap ns service method-protocol: DBupdate SOAP1.2
4954 ~~~
4955 
4956 Use `SOAP` (SOAP 1.1), `SOAP1.1`, `SOAP1.2`, and `HTTP` to switch SOAP versions
4957 or enable REST methods with HTTP POST. See [service directives](#directives-1)
4958 and [XML serialization](#non-soap).
4959 
4960 The soapcpp2 tool auto-generates client and server code. At the client side,
4961 this operation sends data with SOAP 1.2 but accepts responses also in SOAP 1.1.
4962 At the server side, this operation accepts requests in SOAP 1.1 and 1.2 and
4963 will return responses in the same SOAP version.
4964 
4965 As we discussed in the previous section, the SOAP 1.2 protocol has a cleaner
4966 multi-referenced element serialization format that greatly enhances the
4967 accuracy of data graph serialization with SOAP RPC encoding and is therefore
4968 recommended.
4969 
4970 The SOAP 1.2 protocol default can also be set by importing and loading
4971 <i>`gsoap/import/soap12.h`</i>:
4972 
4973 ~~~{.cpp}
4974  #import "soap12.h"
4975 ~~~
4976 
4977 Finally, the soapcpp2 tool has options to force SOAP 1.1, SOAP 1.2, or remove
4978 SOAP altogether with <b>`soapcpp2 -1`</b> (SOAP 1.1), <b>`soapcpp2 -2`</b>
4979 (SOAP 1.2) and <b>`soapcpp2 -0`</b> (plain XML, no SOAP).
4980 
4981 🔝 [Back to table of contents](#)
4982 
4983 XML serialization {#non-soap}
4984 -----------------
4985 
4986 You can serialize data to XML that is stored on the heap, on the stack (locals), and
4987 static data as long as the serializable (i.e. non-transient) values are
4988 properly initialized and pointers in the data structures are either NULL or
4989 point to valid structures.
4990 
4991 When XML is deserialized into data, the data is put on the heap and managed by the
4992 `::soap` context, see also [memory management](#memory).
4993 
4994 You can read and write XML directly to a file or stream with the serializing
4995 [operations on classes and structs](#toxsd9-14).
4996 
4997 To define and use XML Web service client and service operations, we can declare
4998 these operations in your interface header file with the data binding interface
4999 for soapcpp2 as functions. The function are translated by soapcpp2 to
5000 client-side service invocation calls and server-side service operation
5001 dispatchers.
5002 
5003 The REST operations POST, GET, and PUT are declared with `//gsoap` directives
5004 in the interface header file for soapcpp2. For example, a REST HTTP POST
5005 operation is declared as follows:
5006 
5007 ~~~{.cpp}
5008  //gsoap ns service namespace: urn:DB
5009  //gsoap ns service method-protocol: DBupdate POST
5010  int ns__DBupdate(...);
5011 ~~~
5012 
5013 There are no SOAP Envelope and SOAP Body elements in the payload for
5014 `DBupdate`. Also the XML serialization rules are identical to SOAP
5015 document/literal, meaning no SOAP RPC encoding XML structures are implicitly
5016 used. The XML payload only has the operation name as an element with its
5017 parameters serialized as subelements:
5018 
5019 <div class="alt">
5020 ~~~{.xml}
5021  <ns:DBupdate xmln:ns="urn:DB" ...>
5022  ...
5023  </ns:DBupdate>
5024 ~~~
5025 </div>
5026 
5027 To force id-ref serialization with REST similar to SOAP 1.2 multi-reference
5028 encoding, use the `SOAP_XML_GRAPH` flag to initialize the `soap` context.
5029 The XML serialization includes id and ref attributes for multi-referenced
5030 elements as follows:
5031 
5032 <div class="alt">
5033 ~~~{.xml}
5034  <ns:DBupdate xmln:ns="urn:DB" ...>
5035  <records>
5036  <item>
5037  <name id="_1">Joe</name>
5038  <SSN>1234567890</SSN>
5039  </item>
5040  <item>
5041  <name>Jane</name>
5042  <SSN>1987654320</SSN>
5043  </item>
5044  <item>
5045  <name ref="_1"/>
5046  <SSN>2345678901</SSN>
5047  </item>
5048  </records>
5049  </ns:DBupdate>
5050 ~~~
5051 </div>
5052 
5053 🔝 [Back to table of contents](#)
5054 
5055 Input and output {#io}
5056 ================
5057 
5058 Reading and writing XML from/to files, streams and string buffers is done via
5059 the managing `soap` context by setting one of the following context variables that
5060 control IO sources and sinks:
5061 
5062 ~~~{.cpp}
5063  soap->recvfd = fd; // an int file descriptor to read from (0 by default)
5064  soap->sendfd = fd; // an int file descriptor to write to (1 by default)
5065  soap->is = &is; // C++ only: a std::istream is object to read from
5066  soap->os = &os; // C++ only: a std::ostream os object to write to
5067  soap->is = cs; // C only: a const char* string to read from (soap->is will advance)
5068  soap->os = &cs; // C only: pointer to a const char*, will be set to point to the string output
5069 ~~~
5070 
5071 Normally, all of these context variables are NULL, which is required to send and
5072 receive data over sockets by gSOAP client and server applications. Therefore,
5073 if you set any of these context variables in a client or server application
5074 then you should reset them to NULL to ensure that socket communications are not
5075 blocked.
5076 
5077 @note The use of `soap::is` and `soap::os` in C requires gSOAP 2.8.28 or greater.
5078 
5079 In the following sections, we present more details on how to read and write to
5080 files and streams, and use string buffers as sources and sinks for XML data.
5081 
5082 In addition, you can set IO callback functions to handle IO at a lower level.
5083 For more details on defining your own callback functions, see the
5084 [gSOAP user guide.](../../guide/html/index.html)
5085 
5086 🔝 [Back to table of contents](#)
5087 
5088 Reading and writing from/to files and streams {#io1}
5089 ---------------------------------------------
5090 
5091 The default IO is standard input and output. Other sources and sinks (those
5092 listed above) will be used until you (re)set them. For example with file-based
5093 input and output:
5094 
5095 ~~~{.cpp}
5096  FILE *fp = fopen("record.xml", "r");
5097  if (fp != NULL)
5098  {
5099  soap->recvfd = fileno(fp); // get file descriptor of file to read from
5100  if (soap_read_ns__record(soap, &pers1))
5101  ... // handle IO error
5102  fclose(fp);
5103  soap->recvfd = 0; // read from stdin, or -1 to block reading
5104  }
5105 
5106  FILE *fp = fopen("record.xml", "w");
5107  if (fp != NULL)
5108  {
5109  soap->sendfd = fileno(fp); // get file descriptor of file to write to
5110  if (soap_write_ns__record(soap, &pers1))
5111  ... // handle IO error
5112  fclose(fp);
5113  soap->sendfd = 1; // write to stdout, or -1 to block writing
5114  }
5115 ~~~
5116 
5117 Similar code with streams in C++:
5118 
5119 ~~~{.cpp}
5120  #include <fstream>
5121 
5122  std::fstream fs;
5123  fs.open("record.xml", std::ios::in);
5124  if (fs)
5125  {
5126  soap->is = &fs;
5127  if (soap_read__ns__record(soap, &pers1))
5128  ... // handle IO error
5129  fs.close();
5130  soap->is = NULL;
5131  }
5132 
5133  fs.open("record.xml", std::ios::out);
5134  if (fs)
5135  {
5136  soap->os = &fs;
5137  if (soap_write__ns__record(soap, &pers1))
5138  ... // handle IO error
5139  fs.close();
5140  soap->os = NULL;
5141  }
5142 ~~~
5143 
5144 🔝 [Back to table of contents](#)
5145 
5146 Reading and writing from/to string buffers {#io2}
5147 ------------------------------------------
5148 
5149 For C++ we recommend to use `std::stringstream` objects from the
5150 <i>`sstream`</i> C++ library as illustrated in the following example:
5151 
5152 ~~~{.cpp}
5153  #include <sstream>
5154 
5155  std::stringstream ss;
5156  ss.str("..."); // XML to parse
5157  soap->is = &ss;
5158  if (soap_read__ns__record(soap, &pers1))
5159  ... // handle IO error
5160  soap->is = NULL;
5161 
5162  soap->os = &ss;
5163  if (soap_write__ns__record(soap, &pers1))
5164  ... // handle IO error
5165  soap->os = NULL;
5166  std::string s = ss.str(); // string with XML
5167 ~~~
5168 
5169 For C we can use `soap::is` and `soap::os` to point to strings of XML content
5170 as follows (this requires gSOAP 2.8.28 or later):
5171 
5172 ~~~{.cpp}
5173  soap->is = "..."; // XML to parse
5174  if (soap_read__ns__record(soap, &pers1))
5175  ... // handle IO error
5176  soap->is = NULL;
5177 
5178  const char *cs = NULL;
5179  soap->os = &cs;
5180  if (soap_write__ns__record(soap, &pers1))
5181  ... // handle IO error
5182  soap->os = NULL;
5183  ... = cs; // string with XML (do not free(cs): managed by the context and freed with soap_end())
5184 ~~~
5185 
5186 The type of `soap::os` is a pointer to a `const char*` string. The pointer is
5187 set by the managing `soap` context to point to the XML data that is stored on
5188 the context-managed heap.
5189 
5190 For earlier gSOAP versions we recommend to use IO callbacks `soap::frecv` and
5191 `soap::fsend`, see the [gSOAP user guide.](../../guide/html/index.html).
5192 
5193 🔝 [Back to table of contents](#)
5194 
5195 Memory management {#memory}
5196 =================
5197 
5198 Memory management with the `soap` context enables us to allocate data in
5199 context-managed heap space that can be collectively deleted. All deserialized
5200 data is placed on the context-managed heap by the `soap` context of the engine.
5201 
5202 🔝 [Back to table of contents](#)
5203 
5204 Memory management in C {#memory1}
5205 ----------------------
5206 
5207 When working with gSOAP in C (i.e. using <b>`wsdl2h -c`</b> option <b>`-c`</b>
5208 or <b>`soapcpp2 -c`</b> option <b>`-c`</b>), data is allocated on the managed heap with:
5209 
5210 - `void *soap_malloc(struct soap*, size_t len)`.
5211 
5212 This function allocates `len` bytes on the heap managed by the specified
5213 context and returns NULL when allocation failed.
5214 
5215 You can also make shallow copies of data with `soap_memdup` that uses
5216 `soap_malloc` and a safe version of `memcpy` to copy a chunk of data `src` with
5217 length `len` to the context-managed heap:
5218 
5219 - `void * soap_memdup(struct soap*, const void *src, size_t len)`
5220 
5221 This function returns a pointer to the copy. This function requires gSOAP
5222 2.8.27 or later.
5223 
5224 In gSOAP 2.8.35 and greater versions, you can use an auto-generated function to
5225 allocate and initialize data of type `T` on the managed heap:
5226 
5227 - `T * soap_new_T(struct soap*, int n)`
5228 
5229 This function returns an array of length `n` of type `T` data that is default
5230 initialized (by internally calling `soap_malloc(soap, n * sizeof(T))` and then
5231 `soap_default_T(soap, T*)` on each array value). Use a negative value or `n=1`
5232 to allocate and initialize a single value. This function returns NULL when
5233 allocation failed.
5234 
5235 The `soap_malloc` function is essentially a wrapper around `malloc`, but
5236 permits the `soap` context to track all heap allocations for collective
5237 deletion with `soap_end(soap)`:
5238 
5239 ~~~{.cpp}
5240  #include "soapH.h"
5241  #include "ns.nsmap"
5242  ...
5243  struct soap *soap = soap_new(); // new context
5244  ...
5245  struct ns__record *record = (struct ns__record*)soap_malloc(soap, sizeof(struct ns__record));
5246  soap_default_ns__record(soap, record); // auto-generated struct initializer
5247  ...
5248  soap_destroy(soap); // only for C++, see section on C++ below
5249  soap_end(soap); // delete record and all other heap allocations
5250  soap_free(soap); // delete context
5251 ~~~
5252 
5253 All data on the managed heap is mass-deleted with `soap_end(soap)` which must
5254 be called before `soap_done(soap)` or `soap_free(soap)`, which end the use of
5255 the `soap` context and free the context, respectively. Use
5256 `soap_free(soap)` only when the context is allocated with `soap_new()`. Use
5257 `soap_done(soap)` only when the context is stack allocated (so cannot be
5258 deleted from the heap).
5259 
5260 The managed heap is checked for memory leaks at run time when the source code
5261 is compiled with option <b>`-DDEBUG`</b>.
5262 
5263 The soapcpp2 auto-generated deserializers in C use `soap_malloc` to allocate
5264 and populate deserialized structures, which are managed by the context for
5265 collective deletion.
5266 
5267 To make `char*` and `wchar_t*` string copies to the context-managed heap, we
5268 can use the functions:
5269 
5270 - `char *soap_strdup(struct soap*, const char *str)` and
5271 
5272 - `wchar_t *soap_wstrdup(struct soap*, const wchar_t *wstr)`.
5273 
5274 If your C compiler supports `typeof` then you can use the following macro to
5275 simplify the managed heap allocation and initialization of primitive values:
5276 
5277 ~~~{.cpp}
5278  #define soap_assign(soap, lhs, rhs) (*(lhs = (typeof(lhs))soap_malloc(soap, sizeof(*lhs))) = rhs)
5279 ~~~
5280 
5281 Pointers to primitive values are often used for optional members. For example,
5282 assume we have the following struct:
5283 
5284 ~~~{.cpp}
5285  struct ns__record
5286  {
5287  const char *name 1; // required (minOccurs=1)
5288  uint64_t *SSN; // optional (pointer means minOccurs=0)
5289  struct ns__record *spouse; // optional (pointer means minOccurs=0)
5290  };
5291 ~~~
5292 
5293 Use `soap_assign` to create a SSN value on the managed heap:
5294 
5295 ~~~{.cpp}
5296  struct soap *soap = soap_new(); // new context
5297  ...
5298  struct ns__record *record = (struct ns__record*)soap_malloc(soap, sizeof(struct ns__record));
5299  soap_default_ns__record(soap, record);
5300  record->name = soap_strdup(soap, "Joe");
5301  soap_assign(soap, record->SSN, 1234567890UL);
5302  ...
5303  soap_end(soap); // delete managed soap_malloc'ed heap data
5304  soap_free(soap); // delete context
5305 ~~~
5306 
5307 Without the `soap_assign` macro, you will need two lines of code, one to
5308 allocate and one to assign (you should also use this if your system can run out
5309 of memory):
5310 
5311 ~~~{.cpp}
5312  assert((record->SSN = (uint64_t*)soap_malloc(soap, sizeof(utint64_t))) != NULL);
5313  *record->SSN = 1234567890UL;
5314 ~~~
5315 
5316 The serializer can serialize any heap, stack, or static allocated data. So we
5317 can also create a new record as follows:
5318 
5319 ~~~{.cpp}
5320  struct soap *soap = soap_new(); // new context
5321  ...
5322  struct ns__record *record = (struct ns__record*)soap_malloc(soap, sizeof(struct ns__record));
5323  static uint64_t SSN = 1234567890UL;
5324  soap_default_ns__record(soap, record);
5325  record->name = "Joe";
5326  record->SSN = &SSN; // safe to use static values: the value of record->SSN is never changed
5327  ...
5328  soap_end(soap); // delete managed soap_malloc'ed heap data
5329  soap_free(soap); // delete context
5330 ~~~
5331 
5332 Use the soapcpp2 auto-generated `soap_dup_T` functions to duplicate data into
5333 another `soap` context (this requires <b>`soapcpp2 -Ec`</b> option <b>`-Ec`</b> to
5334 generate), here shown for C with the second argument `dst` NULL because we want
5335 to allocate a new managed structure:
5336 
5337 ~~~{.cpp}
5338  struct soap *other_soap = soap_new(); // another context
5339  struct ns__record *other_record = soap_dup_ns__record(other_soap, NULL, record);
5340  ...
5341  soap_destroy(other_soap); // only for C++, see section on C++ below
5342  soap_end(other_soap); // delete other_record and all of its deep data
5343  soap_free(other_soap); // delete context
5344 ~~~
5345 
5346 The only reason to use another `soap` context and not to use the primary `soap`
5347 context is when the primary context must be destroyed together with all of the
5348 objects it manages while some of the objects must be kept alive. If the
5349 objects that are kept alive contain deep cycles then this is the only option we
5350 have, because deep copy with a managing `soap` context detects and preserves
5351 these cycles unless the `SOAP_XML_TREE` flag is used with the `soap` context:
5352 
5353 ~~~{.cpp}
5354  struct soap *other_soap = soap_new1(SOAP_XML_TREE); // another context
5355  struct ns__record *other_record = soap_dup_ns__record(other_soap, NULL, record);
5356 ~~~
5357 
5358 The resulting deep copy will be a full copy of the source data structure as a
5359 tree without co-referenced data (i.e. no digraph) and without cycles. Cycles
5360 are pruned and (one of the) pointers that forms a cycle is repaced by NULL.
5361 
5362 You can also deep copy into unmanaged space and use the auto-generated
5363 `soap_del_T()` function (requires <b>`soapcpp2 -Ed`</b> option <b>`-Ed`</b> to generate) to delete
5364 it later:
5365 
5366 ~~~{.cpp}
5367  struct ns__record *other_record = soap_dup_ns__record(NULL, NULL, record);
5368  ...
5369  soap_del_ns__record(other_record); // deep delete record data members
5370  free(other_record); // delete the record
5371 ~~~
5372 
5373 But you should not do this for any data that has deep cycles in its runtime
5374 data structure. Cycles in the data structure will lead to non-termination when
5375 making unmanaged deep copies. Consider for example:
5376 
5377 ~~~{.cpp}
5378  struct ns__record
5379  {
5380  const char *name 1; // required (minOccurs=1)
5381  uint64_t SSN; // required (non-pointer means minOccurs=1)
5382  struct ns__record *spouse; // optional (pointer means minOccurs=0)
5383  };
5384 ~~~
5385 
5386 The code to populate a structure with a mutual spouse relationship:
5387 
5388 ~~~{.cpp}
5389  struct soap *soap = soap_new();
5390  ...
5391  struct ns__record pers1, pers2;
5392  soap_default_ns__record(soap, &pers1);
5393  soap_default_ns__record(soap, &pers2);
5394  pers1.name = "Joe"; // OK to serialize static data
5395  pers1.SSN = 1234567890;
5396  pers1.spouse = &pers2;
5397  pers2.name = soap_strdup(soap, "Jane"); // allocates and copies a string
5398  pers2.SSN = 1987654320;
5399  pers2.spouse = &pers1;
5400  ...
5401  struct ns__record *pers3 = soap_dup_ns__record(NULL, NULL, &pers1); // BAD
5402  struct ns__record *pers4 = soap_dup_ns__record(soap, NULL, &pers1); // OK
5403  soap_set_mode(soap, SOAP_XML_TREE);
5404  struct ns__record *pers5 = soap_dup_ns__record(soap, NULL, &pers1); // OK
5405 ~~~
5406 
5407 The bad case is where there is no context used in the first argument. The deep
5408 copy functions use a context to keep track of co-referenced data nodes and
5409 cycles in the data structure copies, to copy co-referenced nodes just once.
5410 Co-references in a data structure are formed by pointers and smart pointers
5411 such as `std::shared_ptr`, such that at least two pointers point to the same
5412 data.
5413 
5414 The serializer can serialize any heap, stack, or static allocated data, such as
5415 in the code shown above. So we can serialize the stack-allocated `pers1`
5416 record as follows:
5417 
5418 ~~~{.cpp}
5419  FILE *fp = fopen("record.xml", "w");
5420  if (fp != NULL)
5421  {
5422  soap->sendfd = fileno(fp); // file descriptor to write to
5423  soap_set_mode(soap, SOAP_XML_GRAPH); // support id-ref w/o requiring SOAP
5424  soap_clr_mode(soap, SOAP_XML_TREE); // if set, clear
5425  soap_write_ns__record(soap, &pers1);
5426  fclose(fp);
5427  soap->sendfd = -1; // block further writing
5428  }
5429 ~~~
5430 
5431 which produces an XML document record.xml that is similar to:
5432 
5433 <div class="alt">
5434 ~~~{.xml}
5435  <ns:record xmlns:ns="urn:types" id="Joe">
5436  <name>Joe</name>
5437  <SSN>1234567890</SSN>
5438  <spouse id="Jane">
5439  <name>Jane</name>
5440  <SSN>1987654320</SSN>
5441  <spouse ref="#Joe"/>
5442  </spouse>
5443  </ns:record>
5444 ~~~
5445 </div>
5446 
5447 Deserialization of an XML document with a SOAP 1.1/1.2 encoded id-ref graph
5448 leads to the same non-termination problem when we later try to copy the data
5449 into unmanaged memory heap space:
5450 
5451 ~~~{.cpp}
5452  struct soap *soap = soap_new1(SOAP_XML_GRAPH); // support id-ref w/o SOAP
5453  ...
5454  struct ns__record pers1;
5455  FILE *fp = fopen("record.xml", "r");
5456  if (fp != NULL)
5457  {
5458  soap->recvfd = fileno(fp);
5459  if (soap_read_ns__record(soap, &pers1))
5460  ... // handle IO error
5461  fclose(fp);
5462  soap->recvfd = -1; // blocks further reading
5463  }
5464  ...
5465  struct ns__record *pers3 = soap_dup_ns__record(NULL, NULL, &pers1); // BAD
5466  struct ns__record *pers4 = soap_dup_ns__record(soap, NULL, &pers1); // OK
5467  soap_set_mode(soap, SOAP_XML_TREE);
5468  struct ns__record *pers5 = soap_dup_ns__record(soap, NULL, &pers1); // OK
5469 ~~~
5470 
5471 Copying data with `soap_dup_T(soap)` into managed heap memory space is always
5472 safe. Copying into unmanaged heap memory space requires diligence. But
5473 deleting unmanaged data is easy with `soap_del_T()`.
5474 
5475 You can also use `soap_del_T()` to delete structures that you created in C, but
5476 only if these structures are created with `malloc` and do NOT contain pointers
5477 to stack and static data.
5478 
5479 You can unlink one or more allocated objects from the managed heap to allow the
5480 object to live after `soap_end(soap)` by using:
5481 
5482 - `void soap_unlink(struct soap *soap, void *ptr)`
5483 
5484 The unlinked heap-allocated data pointed to by `ptr` can be accessed after
5485 `soap_end(soap)`. Do not forget to free the data with `free(ptr)`. Be aware
5486 that `soap_unlink(soap, ptr)` does not perform a deep unlinkage. If `ptr` is a
5487 struct, pointer members will become invalid when pointing to objects on the
5488 managed heap. Use `soap_unlink(soap, ptr->member)` to unlink `member` as well.
5489 
5490 Finally, when data is allocated in managed memory heap space, either explicitly
5491 with the allocation functions shown above or by the soapcpp2-generated
5492 deserializers, you can delegate the management and deletion of this data to
5493 another `soap` context. That context will be responsible to delete the data
5494 with `soap_end(soap)` later:
5495 
5496 - `void delegate_deletion(struct soap *soap_from, struct soap *soap_to)`
5497 
5498 This allows the `soap_from` context to be deleted with `soap_free(soap_from)`
5499 (assuming it is allocated with `soap_new()`, use `soap_done(soap_from)` when
5500 `soap_from` is stack-allocated) while the managed data remains intact. You
5501 can use this function any time, to delegate management and deletion to another
5502 context `soap_to` and then continue with the current context. You can also use
5503 different source `soap_from` contexts to delegate management and deletion to
5504 the other `soap_to` context. To mass delete all managed data, use
5505 `soap_end(soap_to)`.
5506 
5507 🔝 [Back to table of contents](#)
5508 
5509 Memory management in C++ {#memory2}
5510 ------------------------
5511 
5512 When working with gSOAP in C++, the engine allocates data on a managed heap
5513 using `soap_new_T(soap)` to allocate a type with type name `T`. Managed heap
5514 allocation is tracked by the `soap` context for collective deletion with
5515 `soap_destroy(soap)` for structs, classes, and templates and with
5516 `soap_end(soap)` for everything else.
5517 
5518 You should only use `soap_malloc(struct soap*, size_t len)` to allocate
5519 primitive types because constructors are not invoked. Therefore, `soap_new_T`
5520 is preferred. The auto-generated `T * soap_new_T(struct soap*)` returns data
5521 allocated on the managed heap for type `T`. The data is mass-deleted with
5522 `soap_destroy(soap)` followed by `soap_end(soap)`.
5523 
5524 The `soap_new_T` functions return NULL when allocation fails. C++ exceptions
5525 are never raised by the engine and serializers when data is allocated.
5526 
5527 There are four variations of `soap_new_T` functions to allocate data of type
5528 `T` that soapcpp2 auto-generates:
5529 
5530 - `T * soap_new_T(struct soap*)` returns a new instance of `T` that is default
5531  initialized. For classes, initialization is internally performed using the
5532  soapcpp2 auto-generated `void T::soap_default(struct soap*)` method of the
5533  class, but ONLY IF the soapcpp2 auto-generated default constructor is used
5534  that invokes `soap_default()` and was not replaced by a user-defined default
5535  constructor.
5536 
5537 - `T * soap_new_T(struct soap*, int n)` returns an array of `n` new instances of
5538  `T`. The instances in the array are default initialized as described above.
5539 
5540 - `T * soap_new_req_T(struct soap*, ...)` (structs and classes only) returns a
5541  new instance of `T` and sets the required data members to the values
5542  specified in `...`. The required data members are those with nonzero
5543  minOccurs, see the subsections on
5544  [(smart) pointer members and their occurrence constraints](#toxsd9-8) and
5545  [container and array members and their occurrence constraints](#toxsd9-9).
5546 
5547 - `T * soap_new_set_T(struct soap*, ...)` (structs and classes only) returns a
5548  new instance of `T` and sets the public/serializable data members to the values
5549  specified in `...`.
5550 
5551 The above functions can be invoked with a NULL `soap` context, but you are then
5552 responsible to use `delete T` to remove this instance from the unmanaged heap.
5553 
5554 For example, to allocate a managed `std::string` you can use:
5555 
5556 ~~~{.cpp}
5557  std::string *s = soap_new_std__string(soap);
5558 ~~~
5559 
5560 To throw a `std::bad_alloc` exception when memory allocation fails, we can define the
5561 following class and macro:
5562 
5563 ~~~{.cpp}
5564  class alloc_check {
5565  public:
5566  template<typename T>
5567  T operator=(T ptr)
5568  {
5569  if (ptr == NULL)
5570  throw std::bad_alloc();
5571  return ptr;
5572  }
5573  };
5574 
5575  #define CHECK alloc_check() =
5576 ~~~
5577 
5578 And use `CHECK` as follows to throw an exception when memory allocation fails:
5579 
5580 ~~~{.cpp}
5581  std::string *s = CHECK soap_new_std__string(soap);
5582 ~~~
5583 
5584 To throw a `std::runtime_exception` when memory allocation fails, with file
5585 and line number information where the error occurred, we can define the
5586 following revised version of our exception-throwing macro:
5587 
5588 ~~~{.cpp}
5589  class alloc_failure : public std::runtime_error {
5590  public:
5591  alloc_failure(const char *file, size_t line) : std::runtime_error(error(file, line))
5592  { }
5593  private:
5594  std::string error(const char *file, size_t line) const
5595  {
5596  std::stringstream ss;
5597  ss << "Memory allocation failed in " << file << " at line " << line;
5598  return ss.str();
5599  }
5600  };
5601 
5602  class alloc_check_with_info {
5603  public:
5604  alloc_check_with_info(const char *file, size_t line) : file(file), line(line)
5605  { }
5606  template<typename T>
5607  T operator=(T ptr) const
5608  {
5609  if (ptr == NULL)
5610  throw alloc_failure(file, line);
5611  return ptr;
5612  }
5613  const char *file;
5614  size_t line;
5615  };
5616 
5617  #define CHECK alloc_check_with_info(__FILE__, __LINE__) =
5618 ~~~
5619 
5620 And use `CHECK` as follows to throw an exception with the file and line number
5621 of the location where memory allocation failed:
5622 
5623 ~~~{.cpp}
5624  std::string *s = CHECK soap_new_std__string(soap);
5625 ~~~
5626 
5627 Primitive types and arrays of primitive values may be allocated with
5628 `soap_malloc` (actually, `soap_new_T` calls `soap_malloc` for primitive type
5629 `T`). All primitive types (i.e. no classes, structs, class templates,
5630 containers, and smart pointers) are allocated with `soap_malloc` for reasons of
5631 efficiency.
5632 
5633 You can use a C++ template to simplify the managed allocation and initialization
5634 of primitive values as follows (this is for primitive types only):
5635 
5636 ~~~{.cpp}
5637  template<class T>
5638  T * soap_make(struct soap *soap, T val)
5639  {
5640  T *p = (T*)soap_malloc(soap, sizeof(T));
5641  if (p == NULL)
5642  throw std::bad_alloc();
5643  *p = val;
5644  return p;
5645  }
5646 ~~~
5647 
5648 For example, assuming we have the following class:
5649 
5650 ~~~{.cpp}
5651  class ns__record
5652  {
5653  public:
5654  std::string name; // required (non-pointer means minOccurs=1)
5655  uint64_t *SSN; // optional (pointer means minOccurs=0)
5656  ns__record *spouse; // optional (pointer means minOccurs=0)
5657  };
5658 ~~~
5659 
5660 You can instantiate a record by using the auto-generated
5661 `soap_new_set_ns__record` and use `soap_make` to create a SSN value on the
5662 managed heap as follows:
5663 
5664 ~~~{.cpp}
5665  soap *soap = soap_new(); // new context
5666  ...
5667  ns__record *record = soap_new_set_ns__record(
5668  soap,
5669  "Joe",
5670  soap_make<uint64_t>(soap, 1234567890UL),
5671  NULL);
5672  ...
5673  soap_destroy(soap); // delete record and all other managed instances
5674  soap_end(soap); // delete managed soap_malloc'ed heap data
5675  soap_free(soap); // delete context
5676 ~~~
5677 
5678 All data on the managed heap is mass-deleted with `soap_end(soap)` which must
5679 be called before `soap_done(soap)` or `soap_free(soap)`, which end the use of
5680 the `soap` context and free the context, respectively. Use
5681 `soap_free(soap)` only when the context is allocated with `soap_new()`. Use
5682 `soap_done(soap)` only when the context is stack allocated (so cannot be
5683 deleted from the heap).
5684 
5685 The managed heap is checked for memory leaks at run time when the source code
5686 is compiled with option <b>`-DDEBUG`</b>.
5687 
5688 However, the serializer can serialize any heap, stack, or static allocated
5689 data. So we can also create a new record as follows:
5690 
5691 ~~~{.cpp}
5692  uint64_t SSN = 1234567890UL;
5693  ns__record *record = soap_new_set_ns__record(soap, "Joe", &SSN, NULL);
5694 ~~~
5695 
5696 which will be fine to serialize this record as long as the local `SSN`
5697 stack-allocated value remains in scope when invoking the serializer and/or
5698 using `record`. It does not matter if `soap_destroy` and `soap_end` are called
5699 beyond the scope of `SSN`.
5700 
5701 To facilitate class methods to access the managing context, we can add a soap
5702 context pointer to a class/struct:
5703 
5704 ~~~{.cpp}
5705  class ns__record
5706  {
5707  public:
5708  ...
5709  void create_more(); // needs a context to create more internal data
5710  protected:
5711  struct soap *soap; // the context that manages this instance, or NULL
5712  };
5713 ~~~
5714 
5715 The `soap` context pointer member of the class is set when invoking
5716 `soap_new_T` (and similar) with a non-NULL context argument that will be
5717 assigned to the `soap` member of the class.
5718 
5719 You can also use a template when an array of pointers to values is required.
5720 To create an array of pointers to values, define the following template:
5721 
5722 ~~~{.cpp}
5723  template<class T>
5724  T **soap_make_array(struct soap *soap, T* array, int n) throw (std::bad_alloc)
5725  {
5726  T **p = (T**)soap_malloc(soap, n * sizeof(T*));
5727  if (p == NULL)
5728  throw std::bad_alloc();
5729  for (int i = 0; i < n; ++i)
5730  p[i] = &array[i];
5731  return p;
5732  }
5733 ~~~
5734 
5735 The `array` parameter is a pointer to an array of `n` values. The template
5736 returns an array of `n` pointers that point to the values in that array:
5737 
5738 ~~~{.cpp}
5739  // create an array of 100 pointers to 100 records
5740  int n = 100;
5741  ns__record **precords = soap_make_array(soap, soap_new_ns__record(soap, n), n);
5742  for (int i = 0; i < n; ++i)
5743  {
5744  precords[i]->name = "...";
5745  precords[i]->SSN = soap_make<uint64_t>(1234567890UL + i);
5746  }
5747 ~~~
5748 
5749 Note that `soap_new_ns__record(soap, n)` returns a pointer to an array of `n`
5750 records, which is then used to create an array of `n` pointers to these records.
5751 
5752 Use the soapcpp2 auto-generated `soap_dup_T` functions to duplicate data into
5753 another `soap` context (this requires <b>`soapcpp2 -Ec`</b> option <b>`-Ec`</b> to generate), here shown
5754 for C++ with the second argument `dst` NULL to allocate a new managed object:
5755 
5756 ~~~{.cpp}
5757  soap *other_soap = soap_new(); // another context
5758  ns__record *other_record = soap_dup_ns__record(other_soap, NULL, record);
5759  ...
5760  soap_destroy(other_soap); // delete record and other managed instances
5761  soap_end(other_soap); // delete other data (the SSNs on the heap)
5762  soap_free(other_soap); // delete context
5763 ~~~
5764 
5765 To duplicate base and derived instances when a base class pointer or reference
5766 is provided, use the auto-generated method `T * T::soap_dup(struct soap*)`:
5767 
5768 ~~~{.cpp}
5769  soap *other_soap = soap_new(); // another context
5770  ns__record *other_record = record->soap_dup(other_soap);
5771  ...
5772  soap_destroy(other_soap); // delete record and other managed instances
5773  soap_end(other_soap); // delete other data (the SSNs on the heap)
5774  soap_free(other_soap); // delete context
5775 ~~~
5776 
5777 The only reason to use another context and not to use the primary `soap`
5778 context is when the primary context must be destroyed together with all of the
5779 objects it manages while some of the objects must be kept alive. If the
5780 objects that are kept alive contain deep cycles then this is the only option we
5781 have, because deep copy with a managing `soap` context detects and preserves
5782 these cycles unless the `SOAP_XML_TREE` flag is used with the context:
5783 
5784 ~~~{.cpp}
5785  soap *other_soap = soap_new1(SOAP_XML_TREE); // another context
5786  ns__record *other_record = record->soap_dup(other_soap); // deep tree copy
5787 ~~~
5788 
5789 The resulting deep copy will be a full copy of the source data structure as a
5790 tree without co-referenced data (i.e. no digraph) and without cycles. Cycles
5791 are pruned and (one of the) pointers that forms a cycle is repaced by NULL.
5792 
5793 You can also deep copy into unmanaged space and use the auto-generated
5794 `soap_del_T()` function or the `T::soap_del()` method (requires
5795 <b>`soapcpp2 -Ec`</b> option <b>`-Ec`</b> to generate) to delete it later,
5796 but we should not do this for any data that has deep cycles in its runtime data
5797 structure graph:
5798 
5799 ~~~{.cpp}
5800  ns__record *other_record = record->soap_dup(NULL);
5801  ...
5802  other_record->soap_del(); // deep delete record data members
5803  delete other_record; // delete the record
5804 ~~~
5805 
5806 Cycles in the data structure will lead to non-termination when making unmanaged
5807 deep copies. Consider for example:
5808 
5809 ~~~{.cpp}
5810  class ns__record
5811  {
5812  public:
5813  const char *name 1; // required (minOccurs=1)
5814  uint64_t SSN; // required (non-pointer means minOccurs=1)
5815  ns__record *spouse; // optional (pointer means minOccurs=1)
5816  };
5817 ~~~
5818 
5819 The code to populate a structure with a mutual spouse relationship:
5820 
5821 ~~~{.cpp}
5822  soap *soap = soap_new();
5823  ...
5824  ns__record pers1, pers2;
5825  pers1.name = "Joe";
5826  pers1.SSN = 1234567890;
5827  pers1.spouse = &pers2;
5828  pers2.name = "Jane";
5829  pers2.SSN = 1987654320;
5830  pers2.spouse = &pers1;
5831  ...
5832  ns__record *pers3 = soap_dup_ns__record(NULL, NULL, &pers1); // BAD
5833  ns__record *pers4 = soap_dup_ns__record(soap, NULL, &pers1); // OK
5834  soap_set_mode(soap, SOAP_XML_TREE);
5835  ns__record *pers5 = soap_dup_ns__record(soap, NULL, &pers1); // OK
5836 ~~~
5837 
5838 The serializer can serialize any heap, stack, or static allocated data, such as
5839 shown in the code shown above. So we can serialize the stack-allocated `pers1`
5840 record as follows:
5841 
5842 ~~~{.cpp}
5843  FILE *fp = fopen("record.xml", "w");
5844  if (fp != NULL)
5845  {
5846  soap->sendfd = fileno(fp); // file descriptor to write to
5847  soap_set_mode(soap, SOAP_XML_GRAPH); // support id-ref w/o requiring SOAP
5848  soap_clr_mode(soap, SOAP_XML_TREE); // if set, clear
5849  if (soap_write_ns__record(soap, &pers1))
5850  ... // handle IO error
5851  fclose(fp);
5852  soap->sendfd = -1; // block further writing
5853  }
5854 ~~~
5855 
5856 which produces an XML document record.xml that is similar to:
5857 
5858 <div class="alt">
5859 ~~~{.xml}
5860  <ns:record xmlns:ns="urn:types" id="Joe">
5861  <name>Joe</name>
5862  <SSN>1234567890</SSN>
5863  <spouse id="Jane">
5864  <name>Jane</name>
5865  <SSN>1987654320</SSN>
5866  <spouse ref="#Joe"/>
5867  </spouse>
5868  </ns:record>
5869 ~~~
5870 </div>
5871 
5872 Deserialization of an XML document with a SOAP 1.1/1.2 encoded id-ref graph
5873 leads to the same non-termination problem when we later try to copy the data
5874 into unmanaged space:
5875 
5876 ~~~{.cpp}
5877  soap *soap = soap_new1(SOAP_XML_GRAPH); // support id-ref w/o SOAP
5878  ...
5879  ns__record pers1;
5880  FILE *fp = fopen("record.xml", "r");
5881  if (fp != NULL)
5882  {
5883  soap->recvfd = fileno(fp); // file descriptor to read from
5884  if (soap_read_ns__record(soap, &pers1))
5885  ... // handle IO error
5886  fclose(fp);
5887  soap->recvfd = -1; // block further reading
5888  }
5889  ...
5890  ns__record *pers3 = soap_dup_ns__record(NULL, NULL, &pers1); // BAD
5891  ns__record *pers4 = soap_dup_ns__record(soap, NULL, &pers1); // OK
5892  soap_set_mode(soap, SOAP_XML_TREE);
5893  ns__record *pers5 = soap_dup_ns__record(soap, NULL, &pers1); // OK
5894 ~~~
5895 
5896 Copying data with `soap_dup_T(soap)` into managed space is always safe. Copying
5897 into unmanaged space requires diligence. But deleting unmanaged data is easy
5898 with `soap_del_T()`.
5899 
5900 You can also use `soap_del_T()` to delete structures in C++, but only if these
5901 structures are created with `new` (and `new []` for arrays when applicable) for
5902 classes, structs, and class templates and with `malloc` for anything else, and
5903 the structures do NOT contain pointers to stack and static data.
5904 
5905 You can unlink one or more allocated objects from the managed heap to allow the
5906 object to live after `soap_destroy(soap)` and `soap_end(soap)` by using:
5907 
5908 - `void soap_unlink(struct soap *soap, void *ptr)`
5909 
5910 The unlinked heap-allocated data pointed to by `ptr` can be accessed after
5911 `soap_destroy(soap)` and `soap_end(soap)`. Do not forget to free the data with
5912 `delete ptr` (C++ class instance only) or with `free(ptr)` (non-class data).
5913 Be aware that `soap_unlink(soap, ptr)` does not perform a deep unlinkage. If
5914 `ptr` is a struct or class, pointer members will become invalid when pointing
5915 to objects on the managed heap. Use `soap_unlink(soap, ptr->member)` to unlink
5916 `member` as well.
5917 
5918 Finally, when data is allocated in managed memory heap space, either explicitly
5919 with the allocation functions shown above or by the soapcpp2-generated
5920 deserializers, you can delegate the management and deletion of this data to
5921 another `soap` context. That context will be responsible to delete the data
5922 with `soap_destroy(soap)` and `soap_end(soap)` later:
5923 
5924 - `void delegate_deletion(struct soap *soap_from, struct soap *soap_to)`
5925 
5926 This allows the `soap_from` context to be deleted with `soap_free(soap_from)`
5927 (assuming it is allocated with `soap_new()`, use `soap_done(soap_from)` when
5928 `soap_from` is stack-allocated) while the managed data remains intact. You
5929 can use this function any time, to delegate management and deletion to another
5930 context `soap_to` and then continue with the current context. You can also use
5931 different source `soap_from` contexts to delegate management and deletion to
5932 the other `soap_to` context. To mass delete all managed data, use
5933 `soap_destroy(soap_to)` followed by `soap_end(soap_to)`.
5934 
5935 🔝 [Back to table of contents](#)
5936 
5937 Context flags to initialize the soap struct {#flags}
5938 ===========================================
5939 
5940 There are several `soap` context initialization flags and context mode flags to
5941 control XML serialization at runtime. The flags are set with `soap_new1()` to
5942 allocate and initialize a new context:
5943 
5944 ~~~{.cpp}
5945  struct soap *soap = soap_new1(flag1 | flag2 | ... | flagn);
5946  ...
5947  soap_destroy(soap); // delete objects
5948  soap_end(soap); // delete other data and temp data
5949  soap_free(soap); // free context
5950 ~~~
5951 
5952 and with `soap_init1()` for stack-allocated contexts:
5953 
5954 ~~~{.cpp}
5955  struct soap soap;
5956  soap_init1(&soap, flag1 | flag2 | ... | flagn);
5957  ...
5958  soap_destroy(&soap); // delete objects
5959  soap_end(&soap); // delete other data and temp data
5960  soap_done(&soap); // clear context
5961 ~~~
5962 
5963 where `flag1`, `flag2`, ..., `flagn` is one of:
5964 
5965 - `SOAP_C_UTFSTRING`: enables all `std::string` and `char*` strings to
5966  contain UTF-8 content. This option is recommended.
5967 
5968 - `SOAP_C_NILSTRING`: treat empty strings as if they were NULL pointers, i.e.
5969  omits elements and attributes when empty.
5970 
5971 - `SOAP_XML_STRICT`: strictly validates XML while deserializing. Should not be
5972  used together with SOAP 1.1/1.2 encoding style of messaging. Use
5973  <b>`soapcpp2 -s`</b> option <b>`-s`</b> to hard code `SOAP_XML_STRICT` in the
5974  generated serializers. Not recommended with SOAP 1.1/1.2 encoding style
5975  messaging.
5976 
5977 - `SOAP_XML_INDENT`: produces indented XML.
5978 
5979 - `SOAP_XML_CANONICAL`: c14n canonocalization, removes unused `xmlns` bindings
5980  and adds them to appropriate places by applying c14n normalization rules.
5981  Should not be used together with SOAP 1.1/1.2 encoding style messaging.
5982 
5983 - `SOAP_XML_TREE`: write tree XML without id-ref, while pruning data structure
5984  cycles to prevent nontermination of the serializer for cyclic structures.
5985 
5986 - `SOAP_XML_GRAPH`: write graph (digraph and cyclic graphs with shared pointers
5987  to objects) using id-ref attributes. That is, XML with SOAP multi-ref
5988  encoded id-ref elements. This is a structure-preserving serialization format,
5989  because co-referenced data and also cyclic relations are accurately represented.
5990 
5991 - `SOAP_XML_DEFAULTNS`: uses xmlns default namespace declarations, assuming
5992  that the schema attribute form is "qualified" by default (be warned if it is
5993  not, since attributes in the null namespace will get bound to namespaces!).
5994 
5995 - `SOAP_XML_NIL`: emit empty element with <i>`xsi:nil`</i> for all NULL pointers
5996  serialized.
5997 
5998 - `SOAP_XML_IGNORENS`: the XML parser ignores XML namespaces, i.e. element and
5999  attribute tag names match independent of their namespace.
6000 
6001 - `SOAP_XML_NOTYPE`: removes all <i>`xsi:type`</i> attribuation. This option is usually
6002  not needed unless the receiver rejects all <i>`xsi:type`</i> attributes. This option
6003  may affect the quality of the deserializer, which relies on <i>`xsi:type`</i>
6004  attributes to distinguish base class instances from derived class instances
6005  transported in the XML payloads.
6006 
6007 - `SOAP_IO_CHUNK`: to enable HTTP chunked transfers.
6008 
6009 - `SOAP_IO_STORE`: full buffering of outbound messages.
6010 
6011 - `SOAP_ENC_ZLIB`: compress messages, requires compiling with option <b>`-DWITH_GZIP`</b> and
6012  linking with zlib using option <b>`-lz`</b>.
6013 
6014 - `SOAP_ENC_MIME`: enable MIME attachments, see
6015  [DIME/MIME/MTOM attachment binary types](#toxsd10-3).
6016 
6017 - `SOAP_ENC_MTOM`: enable MTOM attachments, see
6018  [DIME/MIME/MTOM attachment binary types](#toxsd10-3).
6019 
6020 @note C++ Web service proxy and service classes have their own `soap` context, either
6021 as a base class (with <b>`soapcpp2 -i`</b> option <b>`-i`</b>) or as a pointer member `soap` that points to
6022 a context (with <b>`soapcpp2 -j`</b> option <b>`-j`</b>). These contexts are allocated when the proxy or
6023 service is instantiated with context flags that are passed to the constructor.
6024 
6025 🔝 [Back to table of contents](#)
6026 
6027 Context parameter settings {#params}
6028 ==========================
6029 
6030 After allocation and initializtion of a `soap` context, several context
6031 parameters can be set (some parameters may require 2.8.31 or greater):
6032 
6033 - `unsigned int soap::maxlevel` is the maximum XML nesting depth levels that
6034  the parser permits. Default initialized to `SOAP_MAXLEVEL` (10000), which is
6035  a redefinable macro in <i>`gsoap/stdsoap2.h`</i>. Set `soap::maxlevel` to a
6036  lower value to restrict XML parsing nesting depth.
6037 
6038 - `long soap::maxlength` is the maximum string content length if not already
6039  constrained by an XML schema validation `maxLength` constraint. Zero means
6040  unlimited string lengths are permitted (unless restricted by XML schema
6041  `maxLength`). Default initialized to `SOAP_MAXLENGTH` (0), which is a
6042  redefinable macro in <i>`gsoap/stdsoap2.h`</i>. Set `soap::maxlength` to a
6043  positive value to restrict the number of (wide) characters in strings parsed,
6044  restrict hexBinary byte length, and restrict base64Binary byte length.
6045 
6046 - `size_t soap::maxoccurs` is the maximum number of array or container elements
6047  permitted by the parser. Must be greater than zero (0). Default initialized
6048  to `SOAP_MAXOCCURS` (100000), which is a redefinable macro in
6049  <i>`gsoap/stdsoap2.h`</i>. Set `soap::maxoccurs` to a positive value to
6050  restrict the number of array and container elements that can be parsed.
6051 
6052 - `soap::version` is the SOAP version used, with 0 for non-SOAP, 1 for SOAP1.1,
6053  and 2 for SOAP1.2. This value is normally set by web service operations, and
6054  is otherwise 0 (non-SOAP). Use `soap_set_version(struct soap*, short)` to
6055  set the value. This controls XML namespaces and SOAP id-ref serialization
6056  when applicable with an encodingStyle (see below).
6057 
6058 - `const char *soap::encodingStyle` is a string that is used with SOAP
6059  encoding, normally NULL for non-SOAP XML. Set this string to "" (empty
6060  string) to enable SOAP encoding style, which supports id-ref graph
6061  serialization (see also the `SOAP_XML_GRAPH` [context flag](#flags)).
6062 
6063 - `int soap::recvfd` is the file descriptor to read and parse source data from.
6064  Default initialized to 0 (stdin). See also [input and output](#io).
6065 
6066 - `int soap::sendfd` is the file descriptor to write data to. Default
6067  initialized to 1 (stdout). See also [input and output](#io).
6068 
6069 - `const char *is` for C: string to read and parse source data from, overriding
6070  the `recvfd` source. Normally NULL. This value must be reset to NULL or
6071  the parser will continue to read from this string content until the NUL
6072  character. See also [input and output](#io).
6073 
6074 - `std::istream *is` for C++: an input stream to read and parse source data
6075  from, overriding the `recvfd` source. Normally NULL. This value must be
6076  reset to NULL or the parser will continue to read from this stream until EOF.
6077  See also [input and output](#io).
6078 
6079 - `const char **os` for C: points to a string (a `const char *`) that will be
6080  set to point to the string output. Normally NULL. This value must be reset
6081  to NULL or the next output will result in reassigning the pointer to point to
6082  the next string that is output. The strings are automatically deallocated by
6083  `soap_end(soap)`. See also [input and output](#io).
6084 
6085 - `std::ostream *os` for C++: an output stream to write output to. Normally
6086  NULL. This value must be reste to NULL or the next output will be send to
6087  this stream. See also [input and output](#io).
6088 
6089 🔝 [Back to table of contents](#)
6090 
6091 Error handling and reporting {#errors}
6092 ============================
6093 
6094 The gSOAP API functions return `SOAP_OK` (zero) or a non-zero error code. The
6095 error code is stored in `int soap::error` of the current `soap` context.
6096 Error messages can be displayed with:
6097 
6098 - `void soap_stream_fault(struct soap*, std::ostream &os)` for C++ only, prints
6099  the error message to an output stream.
6100 
6101 - `void soap_print_fault(struct soap*, FILE *fd)` prints the error message to a
6102  FILE descriptor.
6103 
6104 - `void soap_sprint_fault(struct soap*, char *buf, size_t len)` saves the error
6105  message to a fixed-size buffer allocated with a maximum length.
6106 
6107 - `void soap_print_fault_location(struct soap*, FILE *fd)` prints the location
6108  and part of the XML where the parser encountered an error.
6109 
6110 C++ exceptions are never raised by the engine or serializers, even when data is
6111 allocated.
6112 
6113 A `SOAP_EOM` error code is returned when memory was exhausted during
6114 processing of input and/or output of data.
6115 
6116 An EOF (`SOAP_EOF` or -1) error code is returned when the parser has hit EOF
6117 but expected more input, or when socket communications timed out. In addition
6118 to the `SOAP_EOF` error, the `int soap::errnum` of the `soap` context is
6119 set to the `errno` value of the operation that failed. For timeouts, the
6120 `soap::ernum` value is always 0 instead of an `errno` error code.
6121 
6122 Use `soap_xml_error_check(soap->error)` to check for XML errors. This returns
6123 true (non-zero) when a parsing and validation error has occurred.
6124 
6125 For example:
6126 
6127 ~~~{.cpp}
6128  #include <sstream>
6129 
6130  struct soap *soap = soap_new1(SOAP_XML_INDENT | SOAP_XML_STRICT | SOAP_XML_TREE);
6131  struct ns__record person;
6132  std::stringstream ss;
6133  ss.str("..."); // XML to parse
6134  soap->is = &ss;
6135  if (soap_read__ns__record(soap, &person))
6136  {
6137  if (soap_xml_error_check(soap->error))
6138  std::cerr << "XML parsing error!" << std::endl;
6139  else
6140  soap_stream_fault(soap, std::cerr);
6141  }
6142  else
6143  {
6144  ... // all OK, use person record
6145  }
6146  soap_destroy(soap); // delete objects
6147  soap_end(soap); // delete other data and temp data
6148  soap_free(soap); // free context
6149 ~~~
6150 
6151 When deploying your application on UNIX and Linux systems, UNIX signal handlers
6152 should be added to your code handle signals, in particular `SIGPIPE`:
6153 
6154 ~~~{.cpp}
6155  signal(SIGPIPE, sigpipe_handler);
6156 ~~~
6157 
6158 where the `sigpipe_handler` is a function:
6159 
6160 ~~~{.cpp}
6161  void sigpipe_handler(int x) { }
6162 ~~~
6163 
6164 Other UNIX signals may have to be handled as well.
6165 
6166 The engine is designed for easy memory cleanup after being interrupted. Use
6167 `soap_destroy(soap)` and `soap_end(soap)`, after which the `soap` context can
6168 be reused.
6169 
6170 🔝 [Back to table of contents](#)
6171 
6172 Features and limitations {#features}
6173 ========================
6174 
6175 In general, to use the generated code:
6176 
6177 - Make sure to `#include "soapH.h"` in your code and also define a namespace
6178  table or `#include "ns.nsmap"` with the generated table, where `ns` is the
6179  namespace prefix for services.
6180 
6181 - Use <b>`soapcpp2 -j`</b> option <b>`-j`</b> (C++ only) to generate C++ proxy and service objects.
6182  The auto-generated files include documented inferfaces. Compile with
6183  <i>`soapC.cpp`</i> and link with <b>`-lgsoap++`</b>, or alternatively compile
6184  <i>`gsoap/stdsoap2.cpp`</i>.
6185 
6186 - Without <b>`soapcpp2 -j`</b> option <b>`-j`</b>: client-side uses the auto-generated
6187  <i>`soapClient.cpp`</i> and <i>`soapC.cpp`</i> (or C versions of those).
6188  Compile and link with <b>`-lgsoap++`</b> (<b>`-lgsoap`</b> for C), or
6189  alternatively compile <i>`gsoap/stdsoap2.cpp`</i> (<i>`gsoap/stdsoap2.c`</i>
6190  for C).
6191 
6192 - Without <b>`soapcpp2 -j`</b> option <b>`-j`</b>: server-side uses the
6193  auto-generated <i>`soapServer.cpp`</i> and <i>`soapC.cpp`</i> (or C versions
6194  of those). Compile and link with <b>`-lgsoap++`</b> (<b>`-lgsoap`</b> for
6195  C), or alternatively compile <i>`gsoap/stdsoap2.cpp`</i> (<i>`stdsoap2.c`</i>
6196  for C).
6197 
6198 - Use `soap_new()` or `soap_new1(int flags)` to allocate and initialize a
6199  heap-allocated `soap` context with or without flags. Delete this `soap` context with
6200  `soap_free(struct soap*)`, but only after `soap_destroy(struct soap*)` and
6201  `soap_end(struct soap*)`.
6202 
6203 - Use `soap_init(struct *soap)` or `soap_init1(struct soap*, int flags)` to
6204  initialize a stack-allocated `soap` context with or without flags. End the use of
6205  this context with `soap_done(struct soap*)`, but only after
6206  `soap_destroy(struct soap*)` and `soap_end(struct soap*)`.
6207 
6208 Additional notes with respect to the wsdl2h and soapcpp2 tools:
6209 
6210 - Nested classes, structs, and unions in a interface header file are unnested
6211  by soapcpp2.
6212 
6213 - Use `#import "file.h"` instead of `#include` to import other header files in
6214  a interface header file for soapcpp2. The `#include`, `#define`, and
6215  `#pragma` are accepted by soapcpp2, but are moved to the very start of the
6216  generated code for the C/C++ compiler to include before all generated
6217  definitions. Often it is useful to add an `#include` with a
6218  [volatile type](#toxsd9-2) that includes the actual type declaration, and to
6219  ensure transient types are declared when these are used in a data binding
6220  interface declared in a interface header file for soapcpp2.
6221 
6222 - To remove any SOAP-specific bindings, use <b>`soapcpp2 -0`</b> option <b>`-0`</b>.
6223 
6224 - A interface header file for soapcpp2 should not include any code statements,
6225  only data type declarations. This includes constructor initialization lists
6226  that are not permitted. Use member initializations instead.
6227 
6228 - C++ namespaces are supported. Use <b>`wsdl2h -qname`</b> option
6229  <b>`-qname`</b> to add C++ namespace `name`. Or add a `namespace name { ... }`
6230  to the header file, but the `{ ... }` must cover the entire
6231  header file content from begin to end.
6232 
6233 - Optional XML DOM support can be used to store mixed content or literal XML
6234  content. Otherwise, mixed content may be lost. Use <b>`wsdl2h -d`</b>
6235  option <b>`-d`</b> for XML DOM support and compile and link with
6236  <i>`gsoap/dom.c`</i> or <i>`gsoap/dom.cpp`</i>. For details,
6237  see [XML DOM and XPath](http://www.genivia.com/doc/dom/html).
6238 
6239 🔝 [Back to table of contents](#)
6240 
6241 Removing SOAP namespaces from XML payloads {#nsmap}
6242 ==========================================
6243 
6244 The soapcpp2 tool generates a <i>`.nsmap`</i> file that includes two bindings for SOAP
6245 namespaces. We can remove all SOAP namespaces (and SOAP processing logic) with
6246 <b>`soapcpp2 -0`</b> option <b>`-0`</b> or by simply setting the two entries to NULL:
6247 
6248 ~~~{.cpp}
6249  struct Namespace namespaces[] =
6250  {
6251  {"SOAP-ENV", NULL, NULL, NULL},
6252  {"SOAP-ENC", NULL, NULL, NULL},
6253  ...
6254  };
6255 ~~~
6256 
6257 Once the <i>`.nsmap`</i> is generated, you can copy-paste the content into your
6258 project code. However, if we rerun wsdl2h on updated WSDL/XSD files or
6259 <i>`typemap.dat`</i> declarations then we need to use the updated table.
6260 
6261 In cases that no XML namespaces are used at all, for example with
6262 [XML-RPC](http://www.genivia.com/doc/xml-rpc-json/html), you may use an empty
6263 namespace table:
6264 
6265 ~~~{.cpp}
6266  struct Namespace namespaces[] = {{NULL,NULL,NULL,NULL}};
6267 ~~~
6268 
6269 However, beware that any built-in xsi attributes that are rendered will lack
6270 the proper namespace binding. At least we suggest to use `SOAP_XML_NOTYPE` for
6271 this reason.
6272 
6273 🔝 [Back to table of contents](#)
6274 
6275 Examples {#examples}
6276 ========
6277 
6278 Select the project files below to peruse the source code examples.
6279 
6280 🔝 [Back to table of contents](#)
6281 
6282 Source files
6283 ------------
6284 
6285 - <i>`address.xsd`</i> Address book schema
6286 - <i>`address.cpp`</i> Address book app (reads/writes address.xml file)
6287 - <i>`addresstypemap.dat`</i> Schema namespace prefix name preference for wsdl2h
6288 - <i>`graph.h`</i> Graph data binding (tree, digraph, cyclic graph)
6289 - <i>`graph.cpp`</i> Test graph serialization as tree, digraph, and cyclic
6290 
6291 🔝 [Back to table of contents](#)
6292 
6293 Generated files
6294 ---------------
6295 
6296 - <i>`address.h`</i> data binding interface generated from address.xsd
6297 - <i>`addressStub.h`</i> C++ data binding definitions
6298 - <i>`addressH.h`</i> Serializers
6299 - <i>`addressC.cpp`</i> Serializers
6300 - <i>`address.xml`</i> Address book data generated by address app
6301 - <i>`graphStub.h`</i> C++ data binding definitions
6302 - <i>`graphH.h`</i> Serializers
6303 - <i>`graphC.cpp`</i> Serializers
6304 - <i>`g.xsd`</i> XSD schema with <i>`g:Graph`</i> complexType
6305 - <i>`g.nsmap`</i> xmlns bindings namespace mapping table
6306 
6307 🔝 [Back to table of contents](#)
6308 
6309 Build steps
6310 -----------
6311 
6312 Building the AddressBook example:
6313 
6314  wsdl2h -g -taddresstypemap.dat address.xsd
6315  soapcpp2 -0 -C -S -paddress -I../../import address.h
6316  c++ -I../.. address.cpp addressC.cpp -o address -lgsoap++
6317 
6318 Using <b>`wsdl2h -g -taddresstypemap.dat`</b> option <b>`-g`</b> produces
6319 bindings for global (root) elements in addition to types and option
6320 <b>`-taddresstypemap.dat`</b> specifies a mapping file, see further below.
6321 
6322 In this case the root element <i>`a:address-book`</i> is bound to `_a__address_book`.
6323 The complexType <i>`a:address`</i> is bound to class `a__address`, which is also the
6324 type of `_a__address_book`. This option is not required, but allows you to use
6325 global element tag names when referring to their serializers, instead of their
6326 type name. Using <b>`soapcpp2 -0 -C -S -paddress`</b> option <b>`-0`</b> removes the
6327 SOAP protocol and the combination of the two options <b>`-C`</b> and
6328 <b>`-S`</b> removes client and server code generation (using option <b>`-C`</b>
6329 alone generates client code and using option <b>`-S`</b> alone generates server
6330 code). Option <b>`-paddress`</b> renames the output <i>`soap`</i>-prefixed files to
6331 <i>`address`</i>-prefixed files.
6332 
6333 See the <i>`address.cpp`</i> implementation and [related pages](pages.html).
6334 
6335 The <i>`addresstypemap.dat`</i> file specifies the XML namespace prefix for the
6336 bindings:
6337 
6338  # Bind the address book schema namespace to prefix 'a'
6339 
6340  a = "urn:address-book-example"
6341 
6342  # By default the xsd:dateTime schema type is translated to time_t
6343  # To map xsd:dateTime to struct tm, enable the following line:
6344 
6345  # xsd__dateTime = #import "../../custom/struct_tm.h"
6346 
6347  # ... and compile/link with custom/struct_tm.c
6348 
6349 The DOB field is a <i>`xsd:dateTime`</i>, which is bound to `time_t` by default. To
6350 change this to `struct tm`, enable the import of the `xsd__dateTime` custom
6351 serializer by uncommenting the definition of `xsd__dateTime` in
6352 <i>`addresstypemap.dat`</i>. Then change `soap_dateTime2s` to `soap_xsd__dateTime2s`
6353 in the code.
6354 
6355 Building the graph serialization example:
6356 
6357  soapcpp2 -C -S -pgraph -I../../import graph.h
6358  c++ -I../.. graph.cpp graphC.cpp -o graph -lgsoap++
6359 
6360 To compile without using the <b>`-lgsoap++`</b> library: simply compile
6361 <i>`stdsoap2.cpp`</i> together with the above.
6362 
6363 🔝 [Back to table of contents](#)
6364 
6365 Usage
6366 -----
6367 
6368 To execute the AddressBook example:
6369 
6370  ./address
6371 
6372 To execute the Graph serialization example:
6373 
6374  ./graph
6375