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C and C++ XML Data Bindings
updated Fri Aug 16 2024 by Robert van Engelen
|
This article presents a detailed overview of the gSOAP XML data bindings for C and C++. The XML data bindings for C and C++ are extensively used with gSOAP Web services to serialize C and C++ data in XML as part of the SOAP/XML Web services payloads. Also REST XML with gSOAP relies on XML serialization of C and C++ data via XML data bindings.
The major advantage of XML data bindings is that your application data is always type safe in C and C++ by binding XML schema types to C/C++ types. So integers in XML are bound to C integers, strings in XML are bound to C or C++ strings, complex types in XML are bound to C structs or C++ classes, and so on. The structured data you create and accept will fit the data model and is static type safe. In other words, by leveraging strong typing in C/C++, your XML data meets XML schema validation requirements and satisfies XML interoperability requirements.
In fact, gSOAP data bindings are more powerful than simply representing C/C++ data in XML. The gSOAP tools implement true and tested structure-preserving serialization of C/C++ data in XML, including the serialization of cyclic graph structures with id-ref XML attributes. The gSOAP tools also generate routines for deep copying and deep deletion of C/C++ data structures to simplify memory management. In addition, C/C++ structures are deserialized into managed memory, managed by the gSOAP soap
context.
At the end of this article two examples are given to illustrate the application of XML data bindings. The first simple example address.cpp
shows how to use wsdl2h to bind an XML schema to C++. The C++ application reads and writes an XML file into and from a C++ "address book" data structure as a simple example. The C++ data structure is a vector of address objects. The second example graph.cpp
shows how C++ data can be accurately serialized as a tree, digraph, and cyclic graph in XML. The digraph and cyclic graph serialization rules implement SOAP 1.1/1.2 multi-ref encoding with id-ref attributes to link elements through IDREF XML references, creating a an XML graph with pointers to XML nodes that preserves the structural integrity of the serialized C++ data.
These examples demonstrate XML data bindings only for relatively simple data structures and types. The gSOAP tools support more than just these type of structures to serialize in XML. There are practically no limits to the serialization of C and C++ data types in XML.
Also the support for XML schema (XSD) components is unlimited. The wsdl2h tool maps schemas to C and C++ using built-in intuitive mapping rules, while allowing the mappings to be customized using a typemap.dat
file with mapping instructions for wsdl2h.
The information in this article is applicable to gSOAP 2.8.26 and greater that support C++11 features. However, C++11 is not required. The material and the examples in this article use plain C and C++, until the point where we introduce C++11 smart pointers and scoped enumerations. While most of the examples in this article are given in C++, the concepts also apply to C with the exception of containers, smart pointers, classes and their methods. None of these exceptions limit the use of the gSOAP tools for C in any way.
The data binding concepts described in this article were first envisioned in 1999 by Prof. Robert van Engelen at the Florida State University. An implementation was created in 2000, named "stub/skeleton compiler". The first articles on its successor version "gSOAP" appeared in 2002. The principle of mapping XSD components to C/C++ types and vice versa is now widely adopted in systems and programming languages, including Java web services and by C# WCF.
We continue to be committed to our goal to empower C/C++ developers with powerful autocoding tools for XML. Our commitment started in the very early days of SOAP by actively participating in SOAP interoperability testing, participating in the development and testing of the W3C XML Schema Patterns for Databinding Interoperability, and continues by contributing to the development of OASIS open standards in partnership with leading IT companies in the world.
The typographical conventions used by this document are:
Courier
denotes C and C++ source code.Courier
denotes XML content, JSON content, file and path names, and URIs.Courier
denotes HTTP content, text file content, and shell commands with command line options and arguments.The keywords "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in RFC-2119.
To convert WSDL and XML schemas (XSD files) to code, we use the wsdl2h command on the command line (or command prompt), after opening a terminal. The wsdl2h command generates the data binding interface code that is saved to a special Web services and data bindings interface header file with extension .h
that contains the WSDL service declarations and the data binding interface declarations in a familiar C/C++ format:
wsdl2h [options] -o file.h ... XSD and WSDL files ...
This command converts WSDL and XSD files to C++ (or pure C with wsdl2h -c
) and saves the data binding interface to a interface header file file.h
that uses familiar C/C++ syntax extended with //gsoap
directives and annotations. Notational conventions are used in the data binding interface to declare serializable C/C++ types and functions for Web service operations.
The WSDL 1.1/2.0, SOAP 1.1/1.2, and XSD 1.0/1.1 standards are supported by the gSOAP tools. In addition, the most popular WS specifications are also supported, including WS-Addressing, WS-ReliableMessaging, WS-Discovery, WS-Security, WS-Policy, WS-SecurityPolicy, and WS-SecureConversation.
This article focusses mainly on XML data bindings. XML data bindings for C/C++ bind XML schema types to C/C++ types. So integers in XML are bound to C integers, strings in XML are bound to C or C++ strings, complex types in XML are bound to C structs or C++ classes, and so on.
A data binding is dual, meaning supporting a two way direction for development. Either you start with WSDLs and/or XML schemas that are mapped to equivalent C/C++ types, or you start with C/C++ types that are mapped to XSD types. Either way, the end result is that you can serialize C/C++ types in XML such that your XML is an instance of XML schema(s) and is validated against these schema(s).
This covers all of the following standard XSD components with their optional attributes and properties:
XSD component | attributes and properties |
---|---|
schema | targetNamespace, version, elementFormDefault, attributeFormDefault, defaultAttributes |
attribute | name, ref, type, use, default, fixed, form, targetNamespace, wsdl:arrayType |
element | name, ref, type, default, fixed, form, nillable, abstract, substitutionGroup, minOccurs, maxOccurs, targetNamespace |
simpleType | name |
complexType | name, abstract, mixed, defaultAttributesApply |
all | n/a |
choice | minOccurs, maxOccurs |
sequence | minOccurs, maxOccurs |
group | name, ref, minOccurs, maxOccurs |
attributeGroup | name, ref |
any | minOccurs, maxOccurs |
anyAttribute | n/a |
And also the following standard XSD directives are covered:
directive | description |
---|---|
import | Imports a schema into the importing schema for referencing |
include | Include schema component definitions into a schema |
override | Override by replacing schema component definitions |
redefine | Extend or restrict schema component definitions |
annotation | Annotates a component |
The XSD facets and their mappings to C/C++ are:
XSD facet | maps to |
---|---|
enumeration | enum |
simpleContent | class/struct wrapper with __item member |
complexContent | class/struct |
list | enum* bitmask (enum* enumerates a bitmask up to 64 bits) |
extension | class/struct inheritance/extension |
restriction | typedef and class/struct inheritance/redeclaration |
length | typedef with restricted content length annotation |
minLength | typedef with restricted content length annotation |
maxLength | typedef with restricted content length annotation |
minInclusive | typedef with numerical value range restriction annotation |
maxInclusive | typedef with numerical value range restriction annotation |
minExclusive | typedef with numerical value range restriction annotation |
maxExclusive | typedef with numerical value range restriction annotation |
precision | typedef with pattern annotation (pattern used for output, but input is not validated) |
scale | typedef with pattern annotation (pattern used for output, but input is not validated) |
totalDigits | typedef with pattern annotation (pattern used for output, but input is not validated) |
fractionDigits | typedef with pattern annotation (pattern used for output, but input is not validated) |
pattern | typedef with pattern annotation (define soap::fsvalidate callback to validate patterns) |
union | string with union of value |
All primitive XSD types are supported, including but not limited to the following XSD types:
XSD type | maps to |
---|---|
any/anyType | _XML string with literal XML content (or enable DOM with wsdl2h option -d ) |
anyURI | string (i.e. char* , wchar_t* , std::string , std::wstring ) |
string | string (i.e. char* , wchar_t* , std::string , std::wstring ) |
boolean | bool (C++) or enum xsd__boolean (C) |
byte | char (i.e. int8_t ) |
short | short (i.e. int16_t ) |
int | int (i.e. int32_t ) |
long | LONG64 (i.e. long long and int64_t ) |
unsignedByte | unsigned char (i.e. uint8_t ) |
unsignedShort | unsigned short (i.e. uint16_t ) |
unsignedInt | unsigned int (i.e. uint32_t ) |
unsignedLong | ULONG64 (i.e. unsigned long long and uint64_t ) |
float | float |
double | double |
integer | string or #import "custom/int128.h" to use 128 bit xsd__integer |
decimal | string or #import "custom/long_double.h" to use long double |
precisionDecimal | string |
duration | string or #import "custom/duration.h" to use 64 bit xsd__duration |
dateTime | time_t or #import "custom/struct_tm.h" to use struct tm for xsd__dateTime |
time | string or #import "custom/long_time.h" to use 64 bit xsd__time |
date | string or #import "custom/struct_tm_date.h" to use struct tm for xsd__date |
hexBinary | special class/struct xsd__hexBinary |
base64Binary | special class/struct xsd__base64Binary |
QName | _QName string (URI normalization rules are applied) |
All other primitive XSD types not listed above are mapped to strings, by wsdl2h generating a typedef
to string for these types. For example, xsd:token
is bound to a C++ or C string:
This associates a compatible value space to the type with the appropriate XSD type name used by the soapcpp2-generated serializers.
It is possible to remap types by adding the appropriate mapping rules to typemap.dat
as we will explain in more detail in the next section.
Imported custom serializers are intended to extend the C/C++ type bindings when the default binding to string is not satisfactory to your taste and if the target platform supports these C/C++ types. To add custom serializers to typemap.dat
for wsdl2h, see adding custom serializers below.
Use a typemap.dat
file to redefine namespace prefixes and to customize type bindings for the the generated header files produced by the wsdl2h tool. The typemap.dat
is the default file processed by wsdl2h. Use wsdl2h -tfile.dat
option -tfile.dat
to specify a different mapping file file.dat
.
Declarations in typemap.dat
can be broken up over multiple lines by continuing on the next line by ending each line to be continued with a backslash \
. The limit is 4095 characters per line, whether the line is broken up or not.
The wsdl2h tool generates C/C++ type declarations that use ns1
, ns2
, etc. as schema-binding URI prefixes. These default prefixes are generated somewhat arbitrarily for each schema targetNamespace URI, meaning that their ordering may change depending on the WSDL and XSD order of processing with wsdl2h.
Therefore, it is strongly recommended to declare your own prefix for each schema URI in typemap.dat
to reduce maintaince effort of your code. This is more robust when anticipating possible changes of the schema(s) and/or the binding URI(s) and/or the tooling algorithms.
The first and foremost important thing to do is to define prefix-URI bindings for our C/C++ code by adding the following line(s) to our typemap.dat
or make a copy of this file and add the line(s) that bind our choice of prefix name to each URI:
prefix = "URI"
For example, to use g
as a prefix for the "urn:graph" XML namespace:
g = "urn:graph"
This produces g__name
C/C++ type names that are bound to the "urn:graph" schema by association of g
to the generated C/C++ types.
This means that <g:name xmlns:g="urn:graph">
is parsed as an instance of a g__name
C/C++ type. Also <x:name xmlns:x="urn:graph">
parses as an instance of g__name
, because the prefix x
has the same URI value urn:graph
. Prefixes in XML have local scopes (like variables in a block).
The first run of wsdl2h will reveal the XML namespace URIs, so you do not need to search WSDLs and XSD files for all of the target namespaces. Just copy them from the generated header file after the first run into typemap.dat
for editing.
typemap.dat
. That is, do not use the same prefix for multiple XML namespace URIs. This is to avoid namespace conflicts that may cause failed builds and failures in XML parsing and XML schema validation.Custom C/C++ type bindings can be declared in typemap.dat
to associate C/C++ types with specific schema types. These type bindings have four parts:
prefix__type = declaration | use | ptr-use
where
prefix__type
is the schema type to be customized (the prefix__type
name uses the common double underscore naming convention);declaration
declares the C/C++ type in the wsdl2h-generated header file. This part can be empty if no explicit declaration is needed;use
is an optional part that specifies how the C/C++ type is used in the code. When omitted, it is the same as prefix__type
;ptr-use
is an optional part that specifies how the type is used as a pointer type. By default it is the use
type name with a *
or C++11 std::shared_ptr<type>
when enabled (see further below). If use
is already a pointer type by the presence of a *
in the use
part, then the default ptr-use
type is the same as the use
type (that is, no double pointers **
will be created in this case).For example, to map xsd:duration
to a long long
(LONG64
) type that holds millisecond duration values, we can use the custom serializer declared in gsoap/custom/duration.h
by adding the following line to typemap.dat
:
xsd__duration = #import "custom/duration.h"
Here, we omitted the second and third parts, because xsd__duration
is the name that wsdl2h uses for this type in our generated code so we should leave the use
part unspecified. The third part is omitted to let wsdl2h use xsd__duration *
for pointers or std::shared_ptr<xsd__duration>
if smart pointers are enabled.
To map xsd:string
to wchar_t*
wide strings for C source code output:
xsd__string = | wchar_t* | wchar_t*
For C++ we can use the std::wstring
wide string:
xsd__string = | std::wstring
Note that the first part is empty, because these types do not require a declaration. A ptr-use
part is also defined for wchar_t*
, but this is actually needed because the wsdl2h tool recognizes that the use
part wchar_t*
is already a pointer. By contrast, when using 8-bit strings, it is recommended to use the SOAP_C_UTFSTRING
flag to enable UTF-8 formatted strings.
When the ptr-use
part is not specified, it will be auto-generated as pointer T*
for use
type T
or std::shared_ptr<T>
when the variable $POINTER = std::shared
, see the special variables $CONTAINER, $POINTER, $SIZE and $OPTIONAL.
The declaration
part need not be empty, for example if a type must be declared. For example:
xsd__string = typedef std::string mystring; | mystring | std::optional<mystring>
When a auto-generated declaration
should be preserved but the use
or ptr-use
parts must be redefined, then we use an ellipsis for the declaration
part:
prefix__type = ... | use | ptr-use
The ptr-use
part is also useful to map schema polymorphic types to C types for example, where we need to be able to both handle a base type and its extensions as per schema extensibility. Say we have a base type called ns:base
that is extended, then we can remap this to a C type that permits referening the extended types via a void*
as follows:
ns__base = ... | int __type_base; void*
such that __type_base
and void*
will be used to (de)serialize any data type, including base and its derived types. The __type_base
integer is set to a SOAP_TYPE_T
value to indicate what type of data the void*
pointer points to.
In the previous part we saw how a custom serializer is used to bind xsd:duration
to a long long
(LONG64
or int64_t
) type to store millisecond duration values:
xsd__duration = #import "custom/duration.h"
The xsd__duration
type is an alias of long long
(LONG64
or int64_t
).
While wsdl2h will use this binding declared in typemap.dat
automatically, you will also need to compile gsoap/custom/duration.c
. Each custom serializer has an interface header file to be imported into another interface header file that declares the custom type for soapcpp2 and a serializer implementation file written in C, which should be compiled with the application. You can compile these in C++ (rename files to .cpp
if needed).
A custom serializer is declared in an interface header file for soapcpp2 using extern typedef
. The typedef name declared is serializable, whereas the type on which it is based is not serializable. This declaration can be combined with volatile
when the type should not be redeclared, see volatile classes and structs. For example, the custom serializer for struct tm
is the type xsd__datetime
declared as follows in gsoap/custom/struct_tm.h
:
Another example is xsd__duration
as a custom serializer for the C++11 type std::chrono::nanoseconds
:
Next, we present all pre-defined custom serializers that are available to you.
The wsdl2h tool maps xsd:integer
to a string by default. To map xsd:integer
to the 128 bit big int type __int128_t
:
xsd__integer = #import "custom/int128.h"
The xsd__integer
type is an alias of __int128_t
.
xsd:integer
value space of integers is in principle unbounded and values can be of arbitrary length. A value range fault SOAP_TYPE
(value exceeds native representation) or SOAP_LENGTH
(value exceeds range bounds) will be thrown by the deserializer if the value is out of range.Other XSD integer types that are restrictions of xsd:integer
, are xsd:nonNegativeInteger
and xsd:nonPositiveInteger
, which are further restricted by xsd:positiveInteger
and xsd:negativeInteger
. To bind these types to __int128_t
add the following definitions to typemap.dat
:
xsd__nonNegativeInteger = typedef xsd__integer xsd__nonNegativeInteger 0 : ; xsd__nonPositiveInteger = typedef xsd__integer xsd__nonPositiveInteger : 0 ; xsd__positiveInteger = typedef xsd__integer xsd__positiveInteger 1 : ; xsd__negativeInteger = typedef xsd__integer xsd__negativeInteger : -1 ;
Or simply uncomment these definitions in typemap.dat
when you are using the latest gSOAP releases.
__int128_t
128 bit integers are not supported on your platform and if it is certain that xsd:integer
values are within 64 bit value bounds for your application's use, then you can map this type to LONG64
: xsd__integer = typedef LONG64 xsd__integer;
SOAP_TYPE
or SOAP_LENGTH
will be thrown by the deserializer if the value is out of range.After running wsdl2h and soapcpp2, compile gsoap/custom/int128.c
with your project.
The wsdl2h tool maps xsd:decimal
to a string by default. To map xsd:decimal
to extended precision floating point:
xsd__decimal = #import "custom/long_double.h" | long double
By contrast to all other custom serializers, this serializer enables long double
natively without requiring a new binding name (xsd__decimal
is NOT defined).
If your system supports quadmath.h
quadruple precision floating point __float128
, you can map xsd:decimal
to xsd__decimal
that is an alias of __float128
:
xsd__decimal = #import "custom/float128.h"
xsd:decimal
is in principle a decimal value with arbitraty lengths. A value range fault SOAP_TYPE
will be thrown by the deserializer if the value is out of range.In the XML payload the special values INF
, -INF
, NaN
represent plus or minus infinity and not-a-number, respectively.
After running wsdl2h and soapcpp2, compile gsoap/custom/long_double.c
with your project.
The wsdl2h tool maps xsd:dateTime
to time_t
by default.
The trouble with time_t
when represented as 32 bit long
integers is that it is limited to dates between 1970 and 2038. A 64 bit time_t
is safe to use if the target platform supports it, but lack of 64 bit time_t
portability may still cause date range issues.
For this reason struct tm
should be used to represent wider date ranges. This custom serializer avoids using date and time information in time_t
. You get the raw date and time information. You only lose the day of the week information. It is always Sunday (tm_wday=0
).
To map xsd:dateTime
to xsd__dateTime
which is an alias of struct tm
:
xsd__dateTime = #import "custom/struct_tm.h"
If the limited date range of time_t
is not a problem but you want to increase the time precision with fractional seconds, then we suggest to map xsd:dateTime
to struct timeval
:
xsd__dateTime = #import "custom/struct_timeval.h"
If the limited date range of time_t
is not a problem but you want to use the C++11 time point type std::chrono::system_clock::time_point
(which internally uses time_t
):
xsd__dateTime = #import "custom/chrono_time_point.h"
Again, we should make sure that the dates will not exceed the date range when using the default time_t
binding for xsd:dateTime
or when binding xsd:dateTime
to struct timeval
or to std::chrono::system_clock::time_point
. These are safe to use in applications that use xsd:dateTime
to record date stamps within a given window. Otherwise, we recommend the struct tm
custom serializer.
After running wsdl2h and soapcpp2, compile gsoap/custom/struct_tm.c
with your project.
You could even map xsd:dateTime
to a plain string (use char*
with C and std::string
with C++). For example:
xsd__dateTime = | char*
The wsdl2h tool maps xsd:date
to a string by default. We can map xsd:date
to struct tm
:
xsd__date = #import "custom/struct_tm_date.h"
The xsd__date
type is an alias of struct tm
. The serializer ignores the time part and the deserializer only populates the date part of the struct, setting the time to 00:00:00. There is no unreasonable limit on the date range because the year field is stored as an integer (int
).
After running wsdl2h and soapcpp2, compile gsoap/custom/struct_tm_date.c
with your project.
The wsdl2h tool maps xsd:time
to a string by default. We can map xsd:time
to an unsigned long long
(ULONG64
or uint64_t
) integer with microsecond time precision:
xsd__time = #import "custom/long_time.h"
This type represents 00:00:00.000000 to 23:59:59.999999, from 0
to an upper bound of 86399999999
. A microsecond resolution means that a 1 second increment requires an increment of 1000000 in the integer value. The serializer adds a UTC time zone.
After running wsdl2h and soapcpp2, compile gsoap/custom/long_time.c
with your project.
The wsdl2h tool maps xsd:duration
to a string by default, unless xsd:duration
is mapped to a long long
(LONG64
or int64_t
) type with with millisecond (ms) time duration precision:
xsd__duration = #import "custom/duration.h"
The xsd__duration
type is a 64 bit signed integer that can represent 106,751,991,167 days forwards (positive) and backwards (negative) in time in increments of 1 ms (1/1000 of a second).
Rescaling of the duration value by may be needed when adding the duration value to a time_t
value, because time_t
may or may not have a seconds resolution, depending on the platform and possible changes to time_t
.
Rescaling is done automatically when you add a C++11 std::chrono::nanoseconds
value to a std::chrono::system_clock::time_point
value. To use std::chrono::nanoseconds
as xsd:duration
:
xsd__duration = #import "custom/chrono_duration.h"
This type can represent 384,307,168 days (2^63 nanoseconds) forwards and backwards in time in increments of 1 ns (1/1,000,000,000 of a second).
Certain observations with respect to receiving durations in years and months apply to both of these serializer decoders for xsd:duration
.
After running wsdl2h and soapcpp2, compile gsoap/custom/duration.c
with your project.
The gSOAP distribution includes several custom serializers for Qt types. Also Qt container classes are supported, see the special variables $CONTAINER, $POINTER, $SIZE and $OPTIONAL.
This feature requires gSOAP 2.8.34 or higher and Qt 4.8 or higher.
Each Qt custom serializer has an interface header file for soapcpp2 and a C++ implementation file to be compiled with your project.
Other Qt primitive types that are Qt typedef
s of C/C++ types do not require a custom serializer.
To use Qt strings instead of C++ strings, add the following definition to typemap.dat
:
xsd__string = #import "custom/qstring.h"
After running wsdl2h and soapcpp2, compile gsoap/custom/qstring.cpp
with your project.
To use Qt byte arrays for xsd:base64Binary
instead of the xsd__base64Binary
class, add the following definition to typemap.dat
:
xsd__base64Binary = #import "custom/qbytearray_base64.h"
After running wsdl2h and soapcpp2, compile gsoap/custom/qbytearray_base64.cpp
with your project.
To use Qt byte arrays for xsd:hexBinary
instead of the xsd__base64Binary
class, add the following definition to typemap.dat
:
xsd__hexBinary = #import "custom/qbytearray_hex.h"
After running wsdl2h and soapcpp2, compile gsoap/custom/qbytearray_hex.cpp
with your project.
To use Qt QDateTime for xsd:dateTime
, add the following definition to typemap.dat
:
xsd__dateTime = #import "custom/datetime.h"
After running wsdl2h and soapcpp2, compile gsoap/custom/qdatetime.cpp
with your project.
To use Qt QDate for xsd:date
, add the following definition to typemap.dat
:
xsd__date = #import "custom/qdate.h"
After running wsdl2h and soapcpp2, compile gsoap/custom/qdate.cpp
with your project.
To use Qt QDate for xsd:time
, add the following definition to typemap.dat
:
xsd__time = #import "custom/qtime.h"
After running wsdl2h and soapcpp2, compile gsoap/custom/qtime.cpp
with your project.
All generated classes and structs can be augmented with additional members such as methods, constructors and destructors, and private members:
prefix__type = $ member-declaration
For example, we can add method declarations and private members to a class, say ns__record
as follows:
ns__record = $ ns__record(const ns__record &); // copy constructor ns__record = $ void print(); // a print method ns__record = $ private: int status; // a private member
Method declarations cannot include any code, because soapcpp2's input permits only type declarations, not code.
Type replacements can be given to replace one type entirely with another given type:
prefix__type1 == prefix__type2
This replaces all prefix__type1
by prefix__type2
in the wsdl2h output.
short
by int
and float
by double
).The typemap.dat
$CONTAINER
variable defines the container type to use in the wsdl2h-generated declarations for C++, which is std::vector
by default. For example, to use std::list
as the container in the wsdl2h-generated declarations we add the following line to typemap.dat
:
$CONTAINER = std::list
Also a Qt container can be used instead of the default std::vector
, for example QVector
:
[ #include <QVector> ] $CONTAINER = QVector
To remove containers, use wsdl2h -s
. This also removes std::string
, but you can re-introduce std::string
with xsd__string = | std::string
in typemap.dat
.
The typemap.dat
$POINTER
variable defines the smart pointer to use in the wsdl2h-generated declarations for C++, which replaces the use of *
pointers. For example:
$POINTER = std::shared_ptr
Not all pointers in the generated output are replaced by smart pointers by wsdl2h, such as pointers as union members and pointers as struct/class members that point to arrays of values.
std::shared_ptr
is generally safe to use. Other smart pointers such as std::unique_ptr
and std::auto_ptr
may cause compile-time errors when classes have smart pointer members but no copy constructor (a default copy constructor). A copy constructor is required for non-shared smart pointer copying or swapping.Alternatives to std::shared_ptr
of the form NAMESPACE::shared_ptr
can be assigned to $POINTER
when the namespace NAMESPACE
also implements NAMESPACE::make_shared
and when the shared pointer class provides reset()
andget()
methods and the dereference operator. For example Boost boost::shared_ptr
:
[ #include <boost/shared_ptr.hpp> ] $POINTER = boost::shared_ptr
The user-defined content between [
and ]
ensures that we include the Boost header files that are needed to support boost::shared_ptr
and boost::make_shared
.
The variable $SIZE
defines the type of array sizes, which is int
by default. For example, to change array size types to size_t
:
$SIZE = size_t
Permissible types are int
and size_t
. This variable does not affect the size of dynamic arrays, xsd__hexBinary
and xsd__base64Binary
types, which is always int
.
When C++17 is enabled with wsdl2h and soapcpp2 option -c++17
, you can also semi-automatically enable std::optional
declarations with optional class and structure member variables. This means that std::optional
is used instead of a (smart) pointer to make a member optional.
To enable std::optional
with member variables that are primitive types, typedef
, and enum
automatically:
$OPTIONAL = std::optional
Local unnamed simpleType restrictions may not adopt the specified optional type and still use pointers instead. This limitation may be lifted in a future release.
Any other content to be generated by wsdl2h can be included in typemap.dat
by enclosing it within brackets [
and ]
anywhere in the typemap.dat
file. Each of the two brackets must appear at the start of a new line.
For example, we can add an #import "wsa5.h"
to the wsdl2h-generated output as follows:
[ #import "import/wsa5.h" ]
which emits the #import "import/wsa5.h"
literally at the start of the wsdl2h-generated header file.
The soapcpp2 command generates the data binding implementation code from a data binding interface file.h
:
soapcpp2 [options] file.h
where file.h
is a interface header file that declares the XML data binding interface. The file.h
is typically generated by wsdl2h, but you can also declare one yourself. If so, add //gsoap
directives and declare in this file all our C/C++ types you want to serialize in XML.
You can also declare functions that will be converted to Web service operations by soapcpp2. Global function declarations define service operations, which are of the form:
where arg1
, arg2
, ..., argn
are formal argument declarations of the input and result
is a formal argument for the output, which must be a pointer or reference to the result object to be populated. More information on declaring and implementing service operation functions can be found in the gSOAP user guide.
The following C/C++ types are supported by soapcpp2 and mapped to XSD types and constructs. See the subsections below for more details or follow the links.
Boolean Type | Notes |
---|---|
bool | C++ bool |
enum xsd__boolean | C alternative to C++ bool with false_ and true_ |
Enumeration Type | Notes |
---|---|
enum | enumeration |
enum class | C++11 scoped enumeration, requires soapcpp2 -c++11 |
enum* | a bitmask that enumerates values 1, 2, 4, 8, ... |
enum* class | C++11 scoped enumeration bitmask, requires soapcpp2 -c++11 |
Numerical Type | Notes |
---|---|
char | byte |
short | 16 bit integer |
int | 32 bit integer |
long | 32 bit integer |
LONG64 | 64 bit integer |
xsd__integer | 128 bit integer, use #import "custom/int128.h" |
long long | same as LONG64 |
unsigned char | unsigned byte |
unsigned short | unsigned 16 bit integer |
unsigned int | unsigned 32 bit integer |
unsigned long | unsigned 32 bit integer |
ULONG64 | unsigned 64 bit integer |
unsigned long long | same as ULONG64 |
int8_t | same as char |
int16_t | same as short |
int32_t | same as int |
int64_t | same as LONG64 |
uint8_t | same as unsigned char |
uint16_t | same as unsigned short |
uint32_t | same as unsigned int |
uint64_t | same as ULONG64 |
size_t | transient type (not serializable) |
float | 32 bit float |
double | 64 bit float |
long double | extended precision float, use #import "custom/long_double.h" |
xsd__decimal | quadmath.h library 128 bit quadruple precision float, use #import "custom/float128.h" |
typedef | declares a type name, with optional value range and string length bounds |
String Type | Notes |
---|---|
char* | string (may contain UTF-8 with flag SOAP_C_UTFSTRING ) |
wchar_t* | wide string |
std::string | C++ string (may contain UTF-8 with flag SOAP_C_UTFSTRING ) |
std::wstring | C++ wide string |
char[N] | fixed-size string, requires soapcpp2 -b |
_QName | normalized QName content |
_XML | literal XML string content with wide characters in UTF-8 |
typedef | declares a new string type name, may restrict string length |
Date and Time Type | Notes |
---|---|
time_t | date and time point since epoch |
struct tm | date and time point, use #import "custom/struct_tm.h" |
struct tm | date point, use #import "custom/struct_tm_date.h" |
struct timeval | date and time point, use #import "custom/struct_timeval.h" |
unsigned long long | time point in microseconds, use #import "custom/long_time.h" |
std::chrono::system_clock::time_point | date and time point, use #import "custom/chrono_time_point.h" |
Time Duration Type | Notes |
---|---|
long long | duration in milliseconds, use #import "custom/duration.h" |
std::chrono::nanoseconds | duration in nanoseconds, use #import "custom/chrono_duration.h" |
Classes, Structs, and Members | Notes |
---|---|
class | C++ class with single inheritance only |
struct | C struct or C++ struct without inheritance |
std::shared_ptr<T> | C++11 smart shared pointer |
std::unique_ptr<T> | C++11 smart pointer |
std::auto_ptr<T> | C++ smart pointer |
std::deque<T> | use #import "import/stldeque.h" |
std::list<T> | use #import "import/stllist.h" |
std::vector<T> | use #import "import/stlvector.h" |
std::set<T> | use #import "import/stlset.h" |
template<T> class | a container with begin() , end() , size() , clear() , and insert() methods |
T* | pointer to data of type T |
T* | as a class or struct member: points to data of type T or array of T with member __size |
T[N] | as a class or struct member: fixed-size array of type T |
union | as a class or struct member: requires a variant selector member __union |
void* | as a class or struct member: requires a __type member to indicate the type of object pointed to |
Special Classes and Structs | Notes |
---|---|
Special Array class/struct | single and multidimensional SOAP Arrays |
Special Wrapper class/struct | complexTypes with simpleContent, wraps __item member |
xsd__hexBinary | binary content |
xsd__base64Binary | binary content and optional DIME/MIME/MTOM attachments |
xsd__anyType | DOM elements, use #import "dom.h" |
@xsd__anyAttribute | DOM attributes, use #import "dom.h" |
To bind C/C++ type names to XSD types, a simple form of name prefixing is used by the gSOAP tools by prepending the XML namespace prefix to the C/C++ type name with a pair of undescrores. This also ensures that name clashes cannot occur when multiple WSDL and XSD files are converted to C/C++. Also, C++ namespaces are not sufficiently rich to capture XML schema namespaces accurately, for example when class members are associated with schema elements defined in another XML namespace and thus the XML namespace scope of the member's name is relevant, not just its type.
However, from a C/C++ centric point of view this can be cumbersome. Therefore, colon notation is an alternative to physically augmenting C/C++ names with prefixes.
For example, the following class uses colon notation to bind the record
class to the urn:types
schema:
The colon notation is stripped away by soapcpp2 when generating the data binding implementation code for our project. So the final code just uses record
to identify this class and its constructor/destructor.
When using colon notation make sure to be consistent and not use colon notation mixed with prefixed forms. The qualified name ns:record
differs from ns__record
, because ns:record
is compiled to an unqualified record
name in the source code output by the soapcpp2 tool.
Colon notation also facilitates overruling the elementFormDefault and attributeFormDefault declaration that is applied to local elements and attributes, when declared as members of classes, structs, and unions. With colon notation for class, struct and union members, the corresponding XML elements and attributes are selectively qualified with the specified prefix or unqualified when the prefix is omitted in front of the colon. For more details, see qualified and unqualified members.
A C/C++ identifier name (a type name, member name, function name, or parameter name) is translated to an XML tag name by the following rules:
__
in a name represent the namespace prefix of a name.:
) within a name represent the namespace prefix of a name that is present in XML, but this prefix is not present in the generated C/C++ code.:
) before a name makes the name unqualified in XML._USCORE
is translated to an underscore in the translated XML tag name._DOT
is translated to a dot (.
) in the translated XML tag name._xHHHH
is translated to the Unicode character with code point HHHH (hex).For example, the C/C++ identifier name s_a__my_way
is represented in XML by the tag name s-a:my-way
by translating the prefix s_a
and the local name my_way
. With colon notation, the colon-qualified C/C++ identifier name s_a:my_way
is also represented in XML by the same tag name s-a:my-way
, but the generated C/C++ source code defines and uses the local name my_way
only.
Struct/class member and parameter name translation can be overruled by using backtick XML tags (with gSOAP 2.8.30 and greater).
The C++ bool
type is bound to built-in XSD type xsd:boolean
.
The C alternative is to define an enumeration:
or by defining an enumeration in C with pseudo-scoped enumeration constants:
The XML value space of these types is false
and true
, but also accepted are 0
and 1
values for false
and true
, respectively.
To prevent name clashes, false_
and true_
have a trailing underscore in their enum
symbols. Trailing underscores are removed from the XML value space.
Enumerations are mapped to XSD simpleType enumeration restrictions of xsd:string
, xsd:QName
, and xsd:long
.
Consider for example:
which maps to a simpleType restriction of xsd:string
in the soapcpp2-generated schema:
Enumeration name constants can be pseudo-scoped to prevent name clashes, because enumeration name constants have a global scope in C and C++:
You can also use C++11 scoped enumerations to prevent name clashes:
Here, the enumeration class base type : int
is optional. In place of int
in the example above, we can also use int8_t
, int16_t
, int32_t
, or int64_t
.
The XML value space of the enumertions defined above is RED
, WHITE
, and BLUE
.
Prefix-qualified enumeration name constants are mapped to simpleType restrictions of xsd:QName
, for example:
which maps to a simpleType restriction of xsd:QName
in the soapcpp2-generated schema:
Enumeration name constants can be pseudo-numeric as follows:
which maps to a simpleType restriction of xsd:long
:
The XML value space of this type is 3
, 5
, 7
, and 11
.
Besides (pseudo-) scoped enumerations, another way to prevent name clashes accross enumerations is to start an enumeration name constant with one underscore or followed it by any number of underscores, which makes it unique. The leading and trailing underscores are removed from the XML value space.
The gSOAP soapcpp2 tool permits reusing enumeration name constants across (non-scoped) enumerations as long as these values are assigned the same constant. Therefore, the following is permitted:
A bitmask type is an enum*
"product enumeration" with a geometric, power-of-two sequence of values assigned to the enumeration constants:
where the product enum assigns 1 to SSL3
, 2 to TLS10
, 4 to TLS11
, 8 to TLS12
, and 16 to TLS13
, which allows these enumeration constants to be used in composing bitmasks with |
(bitwise or) &
(bitwise and), and ~
(bitwise not):
The bitmask type maps to a simpleType list restriction of xsd:string
in the soapcpp2-generated XML schema:
The XML value space of this type consists of all 16 possible subsets of the four values, represented by an XML string with space-separated values. For example, the bitmask TLS10 | TLS11 | TLS12
equals 14 and is represented by the XML text TLS10 TLS11 TLS12
.
You can also use C++11 scoped enumerations with bitmasks using enum*
product enumerations:
The base type of a scoped enumeration bitmask, when explicitly given, is ignored. The base type is either int
or int64_t
, depending on the number of constants enumerated in the bitmask.
To convert enum
name constants and bitmasks to a string, we use the auto-generated function for enum T
:
The string returned is stored in an internal buffer of the current soap
context, so you should copy it to keep it from being overwritten. For example, use char *soap_strdup(struct soap*, const char*)
.
To convert a string to an enum
constant or bitmask, we use the auto-generated function
This function takes the name (or names, space-separated for bitmasks) of the enumeration constant in a string str
. Names should be given without the pseudo-scope prefix and without trailing underscores. The function sets val
to the corresponding integer enum constant or to a bitmask. The function returns SOAP_OK
(zero) on success or an error if the string is not a valid enumeration name.
Integer and floating point types are mapped to the equivalent built-in XSD types with the same sign and bit width.
The size_t
type is transient (not serializable) because its width is platform dependent. We recommend to use uint64_t
instead.
The XML value space of integer types are their decimal representations without loss of precision.
The XML value space of floating point types are their decimal representations. The decimal representations are formatted with the printf format string "%.9G"
for floats and the printf format string "%.17lG"
for double. To change the format strings, we can assign new strings to the following soap
context members:
Decimal representations may result in a loss of precision of the least significant decimal. Therefore, the format strings that are used by default are sufficiently precise to avoid loss, but this may result in long decimal fractions in the XML value space.
The long double
extended floating point type requires a custom serializer:
You can now use long double
, which has a serializer that serializes this type as xsd:decimal
. Compile and link your code with the file gsoap/custom/long_double.c
.
The value space of floating point values includes the special values INF
, -INF
, and NaN
. You can check a value for plus or minus infinity and not-a-number as follows:
To assign these values, use:
If your system supports __float128
then you can also use this 128 bit floating point type with a custom serializer:
Then use the xsd__decimal
alias of __float128
, which has a serializer. Do not use __float128
directly, which is transient (not serializable).
To check for INF
, -INF
, and NaN
of a __float128
value use:
The range of a typedef
-defined numerical type can be restricted using the range :
operator with inclusive lower and upper bounds. For example:
This maps to a simpleType restriction of xsd:int
in the soapcpp2-generated schema:
The lower and upper bound of a range are optional. When omitted, values are not bound from below or from above, respectively.
The range of a floating point typedef
-defined type can be restricted within floating point constant bounds.
Also with a floating point typedef
a printf
-format pattern can be given of the form "%[width][.precision]f"
to format decimal values using the given width and precision fields:
This maps to a simpleType restriction of xsd:float
in the soapcpp2-generated schema:
For exclusive bounds, we use the <
operator instead of the :
range operator:
Values eps
of ns__epsilon
are restricted between 0.0 < eps < 1.0
.
This maps to a simpleType restriction of xsd:float
in the soapcpp2-generated schema:
To make just one of the bounds exclusive, while keeping the other bound inclusive, we add a <
on the left or on the right side of the range ':' operator. For example:
It is valid to make both left and right side exclusive with < : <
which is in fact identical to the exlusive range <
operator:
It helps to think of the :
as a placeholder of the value between the two bounds, which is easier to memorize than the shorthand forms of bounds from which the :
is removed:
bounds | validation check | shorthand |
---|---|---|
1 : | 1 <= x | 1 |
1 : 10 | 1 <= x <= 10 | |
: 10 | x <= 10 | |
1 < : < 10 | 1 < x < 10 | 1 < 10 |
1 : < 10 | 1 <= x < 10 | |
: < 10 | x < 10 | < 10 |
1 < : | 1 < x | 1 < |
1 < : 10 | 1 < x <= 10 |
Besides float
, also double
and long double
values can be restricted. For example, consider a nonzero probability extended floating point precision type:
Value range restrictions are validated by the parser for all inbound XML data. A type fault SOAP_TYPE
will be thrown by the deserializer if the value is out of range.
Finally, if your system supports __int128_t
then you can also use this 128 bit integer type with a custom serializer:
Use the xsd__integer
alias of __int128_t
, which has a serializer. Do not use __int128_t
directly, which is transient (not serializable).
To convert numeric values to a string, we use the auto-generated function for numeric type T
:
For numeric types T
, the string returned is stored in an internal buffer of the current soap
context, so you should copy it to keep it from being overwritten. For example, use char *soap_strdup(struct soap*, const char*)
.
To convert a string to a numeric value, we use the auto-generated function
where T
is for example int
, LONG64
, float
, decimal
(the custom serializer name of long double
) or xsd__integer
(the custom serializer name of __int128_t
). The function soap_s2T
returns SOAP_OK
on success or an error when the value is not numeric. For floating point types, "INF"
, "-INF"
and "NaN"
are valid strings to convert to numbers.
String types are mapped to the built-in xsd:string
and xsd:QName
XSD types.
The wide strings wchar_t*
and std::wstring
may contain Unicode that is preserved in the XML value space.
Strings char*
and std::string
can only contain extended Latin, but we can store UTF-8 content that is preserved in the XML value space when the soap
context is initialized with the flag SOAP_C_UTFSTRING
.
#x1
and #x1F
) except for #x9
, #xA
, and #xD
. With the newer XML 1.1 version parsers (including gSOAP) you should be fine.The length of a string of a typedef
-defined string type can be restricted:
which maps to a simpleType restriction of xsd:string
in the soapcpp2-generated schema:
String length restrictions are validated by the parser for inbound XML data. A value length fault SOAP_LENGTH
will be thrown by the deserializer if the string is too long or too short.
In addition, an XSD regex pattern restriction can be associated with a string typedef:
which maps to a simpleType restriction of xsd:string
in the soapcpp2-generated schema:
Pattern restrictions are validated by the parser for inbound XML data only if the soap::fsvalidate
and soap::fwvalidate
callbacks are defined.
Exclusive length bounds can be used with strings:
Fixed-size strings (char[N]
) are rare occurrences in the wild, but apparently still used in some projects to store strings. To facilitate fixed-size string serialization, use soapcpp2 -b
option -b
. For example:
which maps to a simpleType restriction of xsd:string
in the soapcpp2-generated schema:
Fixed-size strings must contain NUL-terminated text and should not contain raw binary data. Also, the length limitation is more restrictive for UTF-8 content (enabled with the SOAP_C_UTFSTRING
) that requires multibyte character encodings. As a consequence, UTF-8 content may be truncated to fit.
Raw binary data can be stored in a xsd__base64Binary
or xsd__hexBinary
structure, or transmitted as a MIME attachment.
The built-in _QName
type is a regular C string type (char*
) that maps to xsd:QName
but has the added advantage that it holds normalized qualified names. There are actually two forms of normalized QName content, to ensure any QName is represented accurately:
The first form of string is used when the prefix (and the binding URI) is defined in the namespace table and is bound to a URI (see the .nsmap file). The second form is used when the URI is not defined in the namespace table and therefore no prefix is available to bind and normalize the URI to.
A _QName
string may contain a sequence of space-separated QName values, not just one, and all QName values are normalized to the format shown above.
To define a std::string
base type for xsd:QName
, we use a typedef
:
The xsd__QName
string content is normalized, just as with the _QName
normalization.
To serialize strings that contain literal XML content to be reproduced in the XML value space, use the built-in _XML
string type, which is a regular C string type (char*
) that maps to plain XML CDATA.
To define a std::string
base type for literal XML content, use a typedef
:
Strings can hold any of the values of the XSD built-in primitive types. We can use a string typedef
to declare the use of the string type as a XSD built-in type:
You must ensure that the string values we populate in this type conform to the XML standard, which in case of xsd:token
is the lexical and value spaces of xsd:token
are the sets of all strings after whitespace replacement of any occurrence of #x9
, #xA
, and #xD
by #x20
and collapsing.
As of version 2.8.49, the gSOAP parser will automatically collapse or replace the white space content when receiving data for XSD types that require white space collapsed or replaced. This normalization is applied to strings directly. The decision to collapse or replace is based on the typedef
name corresponding to the built-in string-based XSD type.
To copy char*
or wchar_t*
strings with a context that manages the allocated memory, use functions
To convert a wide string to a UTF-8 encoded string, use function
The function allocates and returns a string, with its memory being managed by the context.
To convert a UTF-8 encoded string to a wide string, use function
where to
is set to point to an allocated wchar_t*
string. Pass -1
for minlen
and maxlen
to ignore length constraints on the target string. The function returns SOAP_OK
or an error when the length constraints are not met.
The C/C++ time_t
type is mapped to the built-in xsd:dateTime
XSD type that represents a date and time within a time zone (typically UTC).
The XML value space contains ISO 8601 Gregorian time instances of the form [-]CCYY-MM-DDThh:mm:ss.sss[Z|(+|-)hh:mm]
, where Z
is the UTC time zone or a time zone offset (+|-)hh:mm]
from UTC is used.
A time_t
value is considered and represented in UTC by the serializer.
Because the time_t
value range is restricted to dates after 01/01/1970 and before 2038 assuming time_t
is a long
32 bit, care must be taken to ensure the range of xsd:dateTime
values in XML exchanges do not exceed the time_t
range.
This restriction does not hold for struct tm
(time.h
library), which we can use to store and exchange a date and time in UTC without date range restrictions. The serializer uses the struct tm
members directly for the XML value space of xsd:dateTime
:
You will lose the day of the week information. It is always Sunday (tm_wday=0
) and the day of the year is not set either. The time zone is UTC.
This struct tm
type is mapped to the built-in xsd:dateTime
XSD type and serialized with the custom serializer gsoap/custom/struct_tm.h
that declares a xsd__dateTime
type:
Compile and link your code with gsoap/custom/struct_tm.c
.
The struct timeval
(sys/time.h
library) type is mapped to the built-in xsd:dateTime
XSD type and serialized with the custom serializer gsoap/custom/struct_timeval.h
that declares a xsd__dateTime
type:
Compile and link your code with gsoap/custom/struct_timeval.c
.
The same value range restrictions apply to struct timeval
as they apply to time_t
. The added benefit of struct timeval
is the addition of a microsecond-precise clock:
A C++11 std::chrono::system_clock::time_point
type is mapped to the built-in xsd:dateTime
XSD type and serialized with the custom serializer gsoap/custom/chrono_time_point.h
that declares a xsd__dateTime
type:
Compile and link your code with gsoap/custom/chrono_time_point.cpp
.
The struct tm
type is mapped to the built-in xsd:date
XSD type and serialized with the custom serializer gsoap/custom/struct_tm_date.h
that declares a xsd__date
type:
Compile and link your code with gsoap/custom/struct_tm_date.c
.
The XML value space of xsd:date
are Gregorian calendar dates of the form [-]CCYY-MM-DD[Z|(+|-)hh:mm]
with a time zone.
The serializer ignores the time part and the deserializer only populates the date part of the struct, setting the time to 00:00:00. There is no unreasonable limit on the date range because the year field is stored as an integer (int
).
An unsigned long long
(ULONG64
or uint64_t
) type that contains a 24 hour time in microseconds UTC is mapped to the built-in xsd:time
XSD type and serialized with the custom serializer gsoap/custom/long_time.h
that declares a xsd__time
type:
Compile and link your code with gsoap/custom/long_time.c
.
This type represents 00:00:00.000000
to 23:59:59.999999
, from 0 to an upper bound of 86,399,999,999. A microsecond resolution means that a 1 second increment requires an increment of 1,000,000 in the integer value.
The XML value space of xsd:time
are points in time recurring each day of the form hh:mm:ss.sss[Z|(+|-)hh:mm]
, where Z
is the UTC time zone or a time zone offset from UTC is used. The xsd__time
value is always considered and represented in UTC by the serializer.
To convert date and/or time values to a string, we use the auto-generated function for type T
:
For date and time types T
, the string returned is stored in an internal buffer of the current soap
context, so you should copy it to keep it from being overwritten. For example, use char *soap_strdup(struct soap*, const char*)
.
To convert a string to a date/time value, we use the auto-generated function
where T
is for example dateTime
(for time_t
), xsd__dateTime
(for struct tm
, struct timeval
, or std::chrono::system_clock::time_point
). The function soap_s2T
returns SOAP_OK
on success or an error when the value is not a date/time.
The XML value space of xsd:duration
are values of the form PnYnMnDTnHnMnS
where the capital letters are delimiters. Delimiters may be omitted when the corresponding member is not used.
A long long
(LONG64
or int64_t
) type that contains a duration (time lapse) in milliseconds is mapped to the built-in xsd:duration
XSD type and serialized with the custom serializer gsoap/custom/duration.h
that declares a xsd__duration
type:
Compile and link your code with gsoap/custom/duration.c
.
The duration type xsd__duration
can represent 106,751,991,167 days forward and backward with millisecond precision.
Durations that exceed a month are always output in days, rather than months to avoid days-per-month conversion inacurracies.
Durations that are received in years and months instead of total number of days from a reference point are not well defined, since there is no accepted reference time point (it may or may not be the current time). The decoder simple assumes that there are 30 days per month. For example, conversion of "P4M" gives 120 days. Therefore, the durations "P4M" and "P120D" are assumed to be identical, which is not necessarily true depending on the reference point in time.
Rescaling of the duration value by may be needed when adding the duration value to a time_t
value, because time_t
may or may not have a seconds resolution, depending on the platform and possible changes to time_t
.
Rescaling is done automatically when you add a C++11 std::chrono::nanoseconds
value to a std::chrono::system_clock::time_point
value. To use std::chrono::nanoseconds
as xsd:duration
:
Compile and link your code with gsoap/custom/chrono_duration.cpp
.
This type can represent 384,307,168 days (2^63 nanoseconds) forwards and backwards in time in increments of 1 ns (1/1000000000 second).
The same observations with respect to receiving durations in years and months apply to this serializer's decoder.
To convert duration values to a string, we use the auto-generated function
The string returned is stored in an internal buffer, so you should copy it to keep it from being overwritten, Use soap_strdup(struct soap*, const char*)
for example to copy this string.
To convert a string to a duration value, we use the auto-generated function
The function returns SOAP_OK
on success or an error when the value is not a duration.
Classes and structs are mapped to XSD complexTypes. The XML value space consists of XML elements with attributes and subelements, possibly constrained by XML schema validation rules that enforce element and attribute occurrence contraints, numerical value range constraints, and string length and pattern constraints.
Classes that are declared with the gSOAP tools are limited to single inheritence only. The soapcpp2 tool does not allow structs to be inherited.
The class and struct name is bound to an XML namespace by means of the prefix naming convention or by using colon notation:
In the example above, we also added a context pointer to the soap
context that manages this instance. It is set when the instance is created in the engine's context, for example when deserialized and populated by the engine.
The class maps to a complexType in the soapcpp2-generated XML schema:
The following sections apply to both structs and classes. Structs require the use of the struct
keyword with the struct name, otherwise soapcpp2 will throw a syntax error. As is often done in C, use a typedef
to declare a struct
that can be used without the struct
keyword.
Public data members of a class or struct are serializable when their types are serializable. Private and protected members are transient and not serializable.
Also const
and static
members are not serializable, with the exception of const char*
and const wchar_t*
. Types and specific class/struct members can be made transient with the extern
qualifier for types and by marking members with [
and ]
:
By declaring std::ostream
transient with extern
you can use this type wherever you need it without soapcpp2 complaining that this class and any other class or type declared as extern
is not defined. Do not use extern
with typedef
, because this declares a custom serializer, see adding custom serializers.
Marking members transient with [
and ]
makes them transient (and visually makes them stand out). This has otherwise no effect on the generated code for the class or struct to be used in your application code.
Extensible and restricted types in XML schemas are derived types from single simple and complex base types. XML schema derived types are naturally represented by C++ derived classes using single inheritance. Besides the concept of extensions versus restrictions, there are two kinds of derived types: complexTypes with simpleContent, meaning types with XML CDATA values, and complexTypes with complexContent, meaning types with sub-elements. Both are permitted to have one or more XML attributes.
A complexType with simpleContent is defined as a wrapper to contain XML CDATA values and any number of attributes, see wrapper class/struct with simpleContent. Wrapper class/struct types can form a hierarchy of derived types in C++ using inheritance. For example:
The ns__data
class maps to a complexType in the soapcpp2-generated XML schema:
The XML value space consists of an element with the string contents an optional attribute:
By contrast, a complexType with complexContent typically extends a given base complexType. For example:
The ns__base
and ns__derived
classes maps to complexTypes in the soapcpp2-generated XML schema:
The XML value space of ns__derived
consists of three requires child elements and an optional attribute:
Derived types can be used for two main purposes in XML schema by extending or restricting base types. One purpose is to reuse a base type when defining a derived type, such that common parts do not need to be replicated. The second purpose is to be able to use a derived type in place of a base type in XML, which is indicated by an xsi:type
attribute with the qualified name of the derived type. Consider for example the following class that uses the previously declared base types xsd__anyType
and ns__base
:
We can assign base type values to the ns_record
members:
This produces the following XML fragment populated with default values (empty text for strings and zeros for numbers), where element base1
has a simpleContent value and element base2
has two child elements:
We can also assign derived type values to the ns_record
members:
This produces the following XML fragment populated with default values (empty text for strings and zeros for numbers), where element base1
has schema type ns:data
with simpleContent and an attribute, and base2
has schema type ns:derived
with three child elements and an attribute:
Deserialization automatically allocates and assigns a ns__base
class instance to a ns__base
pointer when deserializing the ns:base
schema type and allocates and assigns a ns__derived
class instance to a ns__base
pointer when deserializing the ns:derived
type when an element with xsi:type="ns:derived"
is parsed. All classes are extended by soapcpp2 by a soap_type()
method that returns the unique SOAP_TYPE_T
value of the class T
. This makes it easy to check whether the deserialized data contains a derived type to implement type-safe code, for example:
This example should use the SOAP_XML_STRICT
mode flag to initialize the soap
context to ensure that all required values are present in the deserialized structures.
While single inheritance works well in C++ to represent derived types as we discussed in the previous section, this will obviously not work in C. Two methods to serialize derived types in C are presented here. The first method uses void*
to serialize anything. The second method is more accurate and is relatively new in gSOAP.
To serialize any type is possible with tagged void pointer members to serialize data pointed to by a void*
member, which can be any serializable type, such as derived types. For void*
deserialization to work the XML parsed must contain an xsi:type
attribute with a schema type. Only then can the deserializer instantiate the corresponding serializable C/C++ type. Base types serialized do not require an xsi:type
to indicate the base schema type, so this approach is not guaranteed to work and requires a workaround with an anonymous wrapper struct/class that contains both the base type and a void*
. For example:
The __ns__base
wrapper wraps the ns__base
type to (de)serialize the base
element that has no xsi:type
attribute and uses void*
to (de)serialize the base
element that has xsi:type
attribute. This works fine at the XML parsing level, but the generated XML schema components do not accurately represent the derived type, because it lacks the extension/restriction of the derived type (and the __ns__base
wrapper is invisible).
Using void*
to represent derived types in a base type wrapper is not very accurate because we can serialize anything, not just derived types of a given base type. The wrapper may also hold two values: the base type value and a derived type value. Furthermore, using arrays or containers that hold base and derived types becomes quite tricky because an array item could hold both the base and derived type.
As of gSOAP version 2.8.75, wsdl2h -F
option -F
generates base type structs extended with transient pointer members to its derived types. To serialize the base type itself, all of the pointer members are NULL. If one of the pointer members points to a derived type the derived type is serialized instead. Deserialization is automatic, in that the base type is deserialized if the element has no xsi:type
attribute or the attribute is the base schema type, and a derived type is deserialized if the element has an xsi>type
attribute with the derived schema type.
This method is fully automated for the wsdl2h tool to generate an interface header file for soapcpp2 with the type derivations in C. To use this method to generate code from WSDLs and XSDs, use wsdl2h -F
option -F
. This also works in C++ if desired, but C++ inheritance works fine without this method.
Using this method with soapcpp2 alone using a manually-specified interface header file produces the specified type inheritance in the soapcpp2-generated WSDL and XML schema files as complexType extensions.
The soapcpp2 tool warns if a derived type has multiple base types. At most one base type for a derived type may be specified.
This method with transient pointers to derived types makes it easy to use base and derived types in C:
The ns__base
struct includes the special member ns__derived
that points to a ns__derived
value. This special member must be:
[
and ]
, andns__derived_
works too).To serialize the ns__base
value requires the ns__derived
member to be NULL. To serialize the ns__derived
value requires the ns__derived
member to point to the ns__derived
value to serialize and the ns__base
members are irrelevant.
We can assign the base type value to the ns_record::base
member:
This produces the following XML fragment populated with default values (empty text for strings and zeros for numbers), where element base
has two child elements:
We can also assign the derived type value to the ns_record::base
member:
This produces the following XML fragment populated with default values (empty text for strings and zeros for numbers), where element base
has schema type ns:derived
with three child elements and an attribute:
Deserialization automatically assigns values to the base members for the ns__base
type and populates the ns__derived
member when a derived type with xsi:type="ns:derived"
is parsed. This makes it easy to decompose the deserialized data:
This example requires the SOAP_XML_STRICT
mode flag to initialize the soap
context to ensure that all required values are present in the deserialized structures, otherwise the char*
strings may be NULL since XML validation constraints are not enforced on the XML input.
Deeper levels of simulated inheritance are possible, for example:
This requires two pointer traversals from the base type ns__base
via ns__derived
to reach ns__derived_derived
.
Classes and structs can be declared volatile
in the interface header file for soapcpp2, which only has meaning for the gSOAP tools. This annotation means that these types are already declared elsewhere in your project's source code and you do not want soapcpp2 to generate code with a second declaration of these types.
For example, struct tm
is declared in the time.h
library. You can make it serializable and include a partial list of data members that you want to serialize:
You can declare classes and structs volatile
for any such types you want to serialize by only providing the public data members you want to serialize.
In addition, colon notation is a simple and effective way to bind an existing class or struct to a schema. For example, you can change the tm
name as follows without affecting the code that uses struct tm
generated by soapcpp2:
This struct maps to a complexType in the soapcpp2-generated XML schema:
Classes and structs can be declared mutable
with the gSOAP tools. This means that their definition can be spread out over the source code. This promotes the concept of a class or struct as a row of named values, also known as a named tuple, that can be extended at compile time in your source code with additional members. Because these types differ from the traditional object-oriented principles and design concepts of classes and objects, constructors and destructors cannot be defined (also because we cannot guarantee merging these into one such that all members will be initialized). A default constructor, copy constructor, assignment operation, and destructor will be assigned automatically by soapcpp2.
The members are collected into one definition generated by soapcpp2. Members may be repeated from one definition to another, but only if their associated types are identical. So, for example, a third extension with a value
member with a different type fails:
The mutable
concept has proven to be very useful when declaring and collecting SOAP Headers for multiple services, which are collected into one struct SOAP_ENV__Header
by the soapcpp2 tool.
Class and struct data members in C and C++ may be declared with an optional default initialization value that is provided "inline" with the declaration of the member:
Alternatively, you can use C++11 default initialization syntax:
Any member with a primitive type can be initialized in this way.
These initializations are performed by the default constructor that is added by soapcpp2 to each class and struct (in C++ only). A constructor is only added when a default constructor is not already defined with the class declaration.
You can explicitly (re)initialize an object with these initial values by using the soapcpp2 auto-generated functions:
void T::soap_default(struct soap*)
for class T
(C++ only)void soap_default_T(struct soap*, T*)
for struct T
(C and C++).If T
is a struct or class that has a soap
pointer member to a ::soap
context then this pointer member will be set to the first argument passed to these functions to initialize their soap
pointer member.
Default value initializations can be provided for members that have primitive types (bool
, enum
, time_t
, numeric and string types).
Default value initializations of pointer members is permitted, but the effect is different. To conform to XML schema validation, an attribute member that is a pointer to a primitive type will be assigned the default value when parsed from XML. An element member that is a pointer to a primitive type will be assigned when the element is empty when parsed from XML.
As of gSOAP 2.8.48 and greater, a fixed value can be assigned with a ==
. A fixed value is also verified by the parser's validator.
Default and fixed values for members with or without pointers are best explained with the following two example fragments.
A record class with default values for std::string
(or std::wstring
) attributes and elements is declared as follows:
Also std::unique_ptr
and std::shared_ptr
may be used instead of a regular pointer to strings.
With C char*
(or const char*
, const wchar_t*
) strings in a struct, this becomes:
By contrast to std::string e
, char* e
must be marked 1
to make it required, because pointer members are optional by default.
Attributes are considered optional by default, unless marked as required with the occurrence constraint 1
. Elements are considered required unless the member type is a pointer or if the member is marked optional with occurrence constraint 0
.
Instead of default values, fixed values indicate that the attribute or element must contain that value, and only that value, when provided in XML. A fixed value is specified with a ==
.
Attributes with default or fixed values may be omitted in XML. When absent, the default/fixed value is used at the receiving side, i.e. the deserializer assigns the default/fixed value when the attribute is absent. Therefore, there is no need to make attributes with default/fixed values pointer based, because there is no way to distinguish an omitted attribute from a populated attribute on the receiving side. The c
member in the example above can be a non-pointer for this reason. The wsdl2h tool does not generate pointers for attributes with default/fixed values.
Elements with default or fixed values may be optional and the use of default/fixed values with elements differs from attributes. The default/fixed value of an element is only used for elements that are empty in the XML payload received. Omitted optional elements in the XML payload received are simply absent; no default/fixed value is assigned.
char*
and wchar_t*
with explicit default and fixed values differently than previous versions. Versions prior to 2.8.106 assign the default value when the corresponding XML element is absent, whereas 2.8.106 and greater assign NULL when the XML element is absent, exactly as documented in this updated version of this document. To revert to the old behavior, use soapcpp2 -z4
option -z4
. The change affects members char* f
and char* l
(see below).A record class (can be a struct in C) with fixed values for attributes and elements is declared as follows:
With C char*
(or const char*
, const wchar_t*
) strings in a struct, this becomes:
The XML schema validation rules for the examples above are as follows:
Member | Notes |
---|---|
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") |
b | has no effect when parsing XML (but note: instantiating ns__record_with_default assigns the default value "B") |
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) |
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") |
e | has no effect when parsing XML (but note: instantiating ns__record_with_default assigns the default value "E") |
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) |
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") |
h | attribute must appear once, its value must be "H" (also note: instantiating ns__record_with_fixed assigns the fixed value "H") |
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) |
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") |
k | element must appear once, its value must be "K" (also note: instantiating ns__record_with_fixed assigns the fixed value "K") |
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) |
Members of type char[N]
(fixed length string) can have default and fixed values, when soapcpp2 -b
option -b
is used. Also char**
(pointer to a string) members can have default and fixed values. However, members of this type will be initialized to NULL. The default/fixed values will be assigned with the same rules as for char*
when deserialized from XML.
Class and struct data members are declared as XML attributes by annotating their type with a @
qualifier:
This class maps to a complexType in the soapcpp2-generated XML schema:
An example XML instance of ns__record
is:
Attribute data members are restricted to primitive types (bool
, enum
, time_t
, numeric and string types), xsd__hexBinary
, xsd__base64Binary
, and custom serializers, such as xsd__dateTime
. Custom serializers for types that may be used as attributes should define soap_s2T
and soap_T2s
functions that convert values of type T
to strings and back.
Attribute data members can be pointers and smart pointers to these types, which permits attributes to be optional.
The XML tag name of a class/struct member is the name of the member with the usual XML tag translation, see colon notation.
To override the standard translation of identifier names to XML tag names of attributes and elements, add the XML tag name in backticks (requires gSOAP 2.8.30 or greater):
This class maps to a complexType in the soapcpp2-generated XML schema:
An example XML instance of ns__record
is:
A backtick XML tag name may contain any non-empty sequence of ASCII and UTF-8 characters except white space and the backtick character. A backtick tag can be combined with member constraints and default member initializers:
Class, struct, and union data members are mapped to namespace qualified or unqualified tag names of local elements and attributes. If a data member has no prefix then the default form of qualification is applied based on the element/attribute form that is declared with the XML schema of the class, struct, or union type. If the member name has a namespace prefix by colon notation, then the prefix overrules the default (un)qualified form. Therefore, colon notation is an effective mechanism to control qualification of tag names of individual members of classes, structs, and unions.
The XML schema elementFormDefault and attributeFormDefault declarations control the tag name qualification of local elements and attributes, respectively.
Individual schema declarations of local elements and attributes may overrule this by using the form declaration in an XML schema and by using colon notation to add namespace prefixes to class, struct, and union members in the header file for soapcpp2.
Consider for example an ns__record
class in the ns
namespace in which local elements are qualified and local attributes are unqualified by default:
This class maps to a complexType in the soapcpp2-generated XML schema with targetNamespace "urn:types", elementFormDefault qualified and attributeFormDefault unqualified:
An example XML instance of ns__record
is:
Here the root element <ns:record>
is qualified because it is a root element of the XML schema with target namespace "urn:types". Its local element <ns:spouse>
is namespace qualified because the elementFormDefault of local elements is qualified. Attributes are unqualified.
The default namespace (un)qualification of local elements and attributes can be overruled by adding a prefix to the member name by using colon notation:
The colon notation for member ns:name
forces qualification of its attribute tag in XML. The colon notation for member :spouse
removes qualification from its local element tag:
XML instances of ns__record
have unqualified spouse elements and qualified ns:name attributes:
Members of a class or struct can also be prefixed using the prefix__name
convention or using colon notation prefix:name
. However, this has a different effect by referring to global (root) elements and attributes, see document root element definitions.
Backtick XML tags can be used in place of the member name annotations and will achieve the same effect as described when these tag names are (un)qualified (requires gSOAP 2.8.30 or greater).
//gsoap ns schema namespace:
directive to enable the elementForm
and attributeForm
directives in order to generate valid XML schemas with soapcpp2. See directives for more details.To define and reference XML document root elements we use type names that start with an underscore:
Alternatively, we can use a typedef
to define a document root element with a given type:
This typedef
maps to a global root element that is added to the soapcpp2-generated XML schema:
An example XML instance of _ns__record
is:
Global-level element/attribute definitions are also referenced and/or added to the generated XML schema when serializable data members reference these by their qualified name:
These types map to the following comonents in the soapcpp2-generated XML schema:
Use only use qualified member names when their types match the global-level element types that they refer to. For example:
Therefore, we recommend to use qualified member names only when necessary to refer to standard XSD elements and attributes, such as xsi__type
, and xsd__lang
.
By contrast, colon notation has the desired effect to (un)qualify local tag names by overruling the default element/attribute namespace qualification, see qualified and unqualified members.
As an alternative to prefixing member names, use the backtick tag (requires gSOAP 2.8.30 or greater):
A public pointer-typed data member is serialized by following its (smart) pointer(s) to the value pointed to. To serialize pointers to dynamic arrays of data, please see the next section on container and array members and their occurrence constraints.
Pointers that are NULL and smart pointers that are empty are serialized to produce omitted element and attribute values, unless an element is required and is nillable (struct/class members marked with nullptr
) in which case the element is rendered as an empty element with xsi:nil="true"
.
To control the occurrence requirements of pointer-based data members, occurrence constraints are associated with data members in the form of a range minOccurs : maxOccurs
. For non-repeatable (meaning, not a container or array) data members, there are only three reasonable occurrence constraints:
0:0
means that this element or attribute is prohibited.0:1
means that this element or attribute is optional.1:1
means that this element or attribute is required.Pointer-based data members have a default 0:1
occurrence constraint, making them optional, and their XML schema local element/attribute definition is marked as nillable. Non-pointer data members have a default 1:1
occurence constraint, making them required.
A nullptr
occurrence constraint may be applicable to required elements that are nillable pointer types, thus nullptr 1:1
. This indicates that the element is nillable (can be NULL
or nullptr
). A pointer data member that is explicitly marked as required and nillable with nullptr 1:1
will be serialized as an element with an xsi:nil
attribute, thus effectively revealing the NULL property of its value.
A non-pointer data member that is explicitly marked as optional with 0:1
will be set to its default value when no XML value is presented to the deserializer. A default value can be assigned to a data member that has a primitive type or is a (smart) pointer to primitive type.
Consider for example:
This class maps to a complexType in the soapcpp2-generated XML schema:
An example XML instance of ns__record
with its name
string value set to Joe
, SSN
set to its default, and spouse
set to NULL:
volatile
template in a interface header file for soapcpp2: NAMESPACE::shared_ptr
and NAMESPACE::make_shared
to create shared pointers to objects, where NAMESPACE
is any valid C++ namespace such as std
and boost
if you have Boost installed.Class and struct data member types that are containers std::deque
, std::list
, std::vector
and std::set
are serialized as a collection of the values they contain. You can also serialize dynamic arrays, which is the alternative for C to store collections of data. Let's start with containers.
You can use std::deque
, std::list
, std::vector
, and std::set
containers by importing:
For example, to use a vector data mamber to store names in a record:
To limit the number of names in the vector within reasonable bounds, occurrence constraints are associated with the container. Occurrence constraints are of the form minOccurs : maxOccurs
:
This class maps to a complexType in the soapcpp2-generated XML schema:
volatile
, see smart pointers). For example, std::vector
is declared in gsoap/import/stlvector.h
as: template <typename T> class C
container: simple_vector
container with documentation in the package under gsoap/samples/template
.Because C does not support a container template library, we can use a dynamically-sized array of values. This array is declared as a size-pointer pair of members within a struct or class. The array size information is stored in a special size tag member with the name __size
or __sizeX
, where X
can be any name, or by an $int
member to identify the member as a special size tag:
This struct maps to a complexType in the soapcpp2-generated XML schema:
To limit the number of names in the array within reasonable bounds, occurrence constraints are associated with the array size member. Occurrence constraints are of the form minOccurs : maxOccurs
:
This struct maps to a complexType in the soapcpp2-generated XML schema:
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:
The ns__record
struct maps to a complexType that references the ArrayOfstring
complexType with an sequence of 1 to 100 item
elements:
To change the item
element name in the WSDL, XML schema, and XML messages, use __ptrName
where Name
is the name you want to use.
soapcpp2 -e
option -e
is used, the ArrayOfstring
becomes a SOAP-encoded array for SOAP 1.1/1.2 RPC encoded messaging: Fixed-size arrays can be used to store a fixed number of values:
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 Array10Ofstring
complexType with ten item
elements:
soapcpp2 -e
option -e
is used, the Array10Ofstring
becomes a SOAP-encoded array for SOAP 1.1/1.2 RPC encoded messaging, see previous note.A member becomes a hidden XML element, i.e. not visibly rendered in XML, when its name starts with a double underscore. This makes it possible to sequence a collection of data members, basically by forming a sequence of elements that can be optional or repeated together.
To create a sequence of members that are optional, use a pointer-based hidden member that is a struct with the collection of members to sequence:
Here we used a hidden struct type __ns__optional
which starts with a double underscore, because we do not want to define a new global type for the XML schema we generate. We just need a unique name for a structure that sequences the two members.
This struct maps to a complexType in the soapcpp2-generated XML schema:
The name
member is a required element of the ns:record
complexType. The ns:record
complexType has an optional sequence of SSN
and phone
elements.
To create repetitions of a sequence of members, use an array as follows:
This struct maps to a complexType in the soapcpp2-generated XML schema:
The name
member is a required element of the ns:record
complexType. The ns:record
complexType has a potentially unbounded sequence of SSN
and phone
elements. You can specify array bounds instead of zero to unbounded, see container and array members and their occurrence constraints.
The XML value space consists of a sequence of SSN and phone elements:
A union member in a class or in a struct cannot be serialized unless a discriminating variant selector member is provided that tells the serializer which union field to serialize. This effectively creates a tagged union.
The variant selector is associated with the union as a selector-union pair of members. The variant selector is a member with the name __union
or __unionX
, where X
can be any name, or by an $int
member to identify the member as a variant selector tag:
The variant selector values are auto-generated based on the union name choice
and the names of its members x
, n
, and s
:
xORnORs = SOAP_UNION_ns__choice_x
when u.x
is valid.xORnORs = SOAP_UNION_ns__choice_n
when u.n
is valid.xORnORs = SOAP_UNION_ns__choice_s
when u.s
is valid.xORnORs = 0
when none are valid (should only be used with great care, because XSD validation may fail when content is required but absent).This class maps to a complexType with a sequence and choice in the soapcpp2-generated XML schema:
A container or dynamic array of a union requires wrapping the variant selector and union member in a struct:
and an equivalent definition with a dynamic array instead of a std::vector
(you can use this in C with structs):
This maps to two complexTypes in the soapcpp2-generated XML schema:
The XML value space consists of a sequence of item elements each wrapped in an data element:
To remove the wrapping data element, simply rename the wrapping struct to __ns__data
and the member to __data
to make this member invisible to the serializer. The double underscore prefix naming convention is used for the struct name and member name. Also use a dynamic array instead of a container (so you can also use this approach in C with structs):
This maps to a complexType in the soapcpp2-generated XML schema:
The XML value space consists of a sequence of <x>
, <n>
, and/or <s>
elements:
Please note that structs, classes, and unions are unnested by soapcpp2 (as in the C standard of nested structs and unions). Therefore, the ns__choice
union in the ns__record
class is redeclared at the top level despite its nesting within the ns__record
class. This means that you will have to choose a unique name for each nested struct, class, and union.
To serialize data pointed to by void*
requires run-time type information that tells the serializer what type of data to serialize by means of a tagged void pointer. This type information is stored in a special type tag member of a struct/class with the name __type
or __typeX
, where X
can be any name, or alternatively by an $int
special member of any name as a type tag:
A type tag member has nonzero values SOAP_TYPE_T
where T
is the name of a struct/class or the name of a primitive type, such as int
, std__string
(for std::string
), string
(for char*
).
This class maps to a complexType with a sequence in the soapcpp2-generated XML schema:
The XML value space consists of the XML value space of the type with the addition of an xsi:type
attribute to the enveloping element:
This xsi:type
attribute is important for the receiving end to distinguish the type of data to instantiate. The receiver cannot deserialize the data without an xsd:type
attribute.
You can find the SOAP_TYPE_T
name of each serializable type in the auto-generated soapStub.h
file.
Also all serializable C++ classes have a virtual int T::soap_type()
member that returns their SOAP_TYPE_T
value that you can use.
When the void*
pointer is NULL or when typeOfdata
is zero, the data is not serialized.
A container or dynamic array of void*
pointers to xsd:anyType
data requires wrapping the type tag and void*
members in a struct:
and an equivalent definition with a dynamic array instead of a std::vector
(you can use this in C with structs):
This maps to two complexTypes in the soapcpp2-generated XML schema:
The XML value space consists of a sequence of item elements each wrapped in a data element:
To remove the wrapping data elements, simply rename the wrapping struct and member to __data
to make this member invisible to the serializer with the double underscore prefix naming convention. Also use a dynamic array instead of a container (you can use this in C with structs):
This maps to a complexType in the soapcpp2-generated XML schema:
The XML value space consists of a sequence of data elements:
Again, please note that structs, classes, and unions are unnested by soapcpp2 (as in the C standard of nested structs and unions). Therefore, the __data
struct in the ns__record
class is redeclared at the top level despite its nesting within the ns__record
class. This means that you will have to choose a unique name for each nested struct, class, and union.
A public get
method may be added to a class or struct, which will be triggered by the deserializer. This method will be invoked right after the instance is populated by the deserializer. The get
method can be used to update or verify deserialized content. It should return SOAP_OK
or set soap::error
to a nonzero error code and return it.
A public set
method may be added to a class or struct, which will be triggered by the serializer. The method will be invoked just before the instance is serialized. Likewise, the set
method should return SOAP_OK
or set set soap::error
to a nonzero error code and return it.
For example, adding a set
and get
method to a class declaration:
To add these and othe rmethods to classes and structs with wsdl2h and typemap.dat
, please see class/struct member additions.
The following functions/macros are generated by soapcpp2 for each type T
, which should make it easier to send, receive, and copy XML data in C and in C++:
int soap_write_T(struct soap*, T*)
writes an instance of T
to a file via file descriptor int soap::sendfd)
or to a stream via std::ostream *soap::os
(C++ only) or saves into a NUL-terminated string by setting const char **soap::os
to a string pointer to be set (C only). Returns SOAP_OK
on success or an error code, also stored in soap::error
.int soap_read_T(struct soap*, T*)
reads an instance of T
from a file via file descriptor int soap::recvfd)
or from a stream via std::istream *soap::is
(C++ only) or reads from a NUL-termianted string const char *soap::is
(C only). Returns SOAP_OK
on success or an error code, also stored in soap::error
.void soap_default_T(struct soap*, T*)
sets an instance T
to its default value, resetting members of a struct to their initial values (for classes we use method T::soap_default
, see below). If T
is a struct that has a soap
pointer member to a ::soap
context then this pointer member will be set to the first argument passed to this function to initialize its soap
pointer member.T * soap_dup_T(struct soap*, T *dst, const T *src)
(requires soapcpp2 -Ec
) deep copy src
into dst
, replicating all deep cycles and shared pointers when a managing soap
context is provided as argument. When dst
is NULL, allocates space for dst
and returns a pointer to the allocated copy. Deep copy results in a tree when the soap
context is NULL, but the presence of deep cycles will lead to non-termination. Use flag SOAP_XML_TREE
with managing context to copy into a tree without cycles and pointers to shared objects. Returns dst
or allocated copy when dst
is NULL.void soap_del_T(const T*)
(requires soapcpp2 -Ed
) deletes all heap-allocated members of this object by deep deletion ONLY IF this object and all of its (deep) members are not managed by a soap
context AND the deep structure is a tree (no cycles and co-referenced objects by way of multiple (non-smart) pointers pointing to the same data). Can be safely used after T * soap_dup_T(NULL, NULL, const T*)
to delete the deep copy returned. Does not delete the object itself.When in C++ mode, soapcpp2 tool adds several methods to classes in addition to adding a default constructor and destructor (when these were not explicitly declared).
The public methods added to a class T
:
virtual int T::soap_type(void)
returns a unique type ID (SOAP_TYPE_T
). This numeric ID can be used to distinguish base from derived instances.virtual void T::soap_default(struct soap*)
sets all data members to default values. If class T
has a soap
pointer member to a ::soap
context then this pointer member will be set to the argument passed to this function to initialize its soap
pointer member.virtual void T::soap_serialize(struct soap*) const
serializes object to prepare for SOAP 1.1/1.2 encoded output (or with SOAP_XML_GRAPH
) by analyzing its (cyclic) structures.virtual int T::soap_put(struct soap*, const char *tag, const char *type) const
emits object in XML, compliant with SOAP 1.1 encoding style, return error code or SOAP_OK
. Requires soap_begin_send(soap)
and soap_end_send(soap)
.virtual int T::soap_out(struct soap*, const char *tag, int id, const char *type) const
emits object in XML, with tag and optional id attribute and xsi:type
, return error code or SOAP_OK
. Requires soap_begin_send(soap)
and soap_end_send(soap)
.virtual void * T::soap_get(struct soap*, const char *tag, const char *type)
Get object from XML, compliant with SOAP 1.1 encoding style, return pointer to object or NULL on error. Requires soap_begin_recv(soap)
and soap_end_recv(soap)
.virtual void *soap_in(struct soap*, const char *tag, const char *type)
Get object from XML, with matching tag and type (NULL matches any tag and type), return pointer to object or NULL on error. Requires soap_begin_recv(soap)
and soap_end_recv(soap)
virtual T * T::soap_alloc(void) const
returns a new object of type T
, default initialized and not managed by a soap
context.virtual T * T::soap_dup(struct soap*) const
(requires soapcpp2 -Ec
) returns a duplicate of this object by deep copying, replicating all deep cycles and shared pointers when a managing soap
context is provided as argument. Deep copy is a tree when argument is NULL, but the presence of deep cycles will lead to non-termination. Use flag SOAP_XML_TREE
with the managing context to copy into a tree without cycles and pointers to shared objects.virtual void T::soap_del() const
(rquires soapcpp2 -Ed
) deletes all heap-allocated members of this object by deep deletion ONLY IF this object and all of its (deep) members are not managed by a soap
context AND the deep structure is a tree (no cycles and co-referenced objects by way of multiple (non-smart) pointers pointing to the same data). Can be safely used after soap_dup(NULL)
to delete the deep copy. Does not delete the object itself.Also, there are four variations of soap_new_T
for class/struct/template type T
that soapcpp2 auto-generates to create instances on a context-managed heap:
T * soap_new_T(struct soap*)
returns a new instance of T
with default data member initializations that are set with the soapcpp2 auto-generated void T::soap_default(struct soap*)
method), but ONLY IF the soapcpp2 auto-generated default constructor is used that invokes soap_default()
and was not replaced by a user-defined default constructor.T * soap_new_T(struct soap*, int n)
returns an array of n
new instances of T
. Similar to the above, instances are initialized.T * soap_new_req_T(struct soap*, ...)
returns a new instance of T
and sets the required data members to the values specified in ...
. The required data members are those with nonzero minOccurs, see the subsections on (smart) pointer members and their occurrence constraints and container and array members and their occurrence constraints.T * soap_new_set_T(struct soap*, ...)
returns a new instance of T
and sets the public/serializable data members to the values specified in ...
.The above functions can be invoked with a NULL soap
context, but we will be responsible to use delete T
to remove this instance from the unmanaged heap.
The allocation functions return NULL when memory allocation failed.
The following applies to both structs and classes. The examples show classes in C++. For C, use structs and omit the C++ features. Structs also require the use of the struct
keyword, otherwise soapcpp2 will throw a syntax error.
A class or struct with the following layout is a one-dimensional SOAP-encoded array type:
where T
is the array element type. A multidimensional SOAP Array is:
where N
is the constant number of dimensions. The pointer points to an array of __size[0]*__size[1]* ... * __size[N-1]
elements.
This maps to a complexType restriction of SOAP-ENC:Array in the soapcpp2-generated XML schema:
The name of the class can be arbitrary. We often use ArrayOfT
without a prefix to distinguish arrays from other classes and structs.
With SOAP 1.1 encoding, an optional offset member can be added that controls the start of the index range for each dimension:
For example, we can define a matrix of floats as follows:
The following code populates the matrix and serializes it in XML:
Matrix A is serialized as an array with 2x3 values:
A special case of a one-dimensional array is used to define xsd:hexBinary
and xsd:base64Binary
types when the pointer type is unsigned char
:
and
To create a new binary type, use either one of the following three forms that declare a new ns__binary
type that is a simpleType
restriction of xsd:base64Binary
:
Here, xsd__base64Binary
is reused in the first two cases, where xsd__base64Binary
is declared as shown above.
A class or struct with a binary content layout can be extended to support attachments. The following struct or class type can be used as DIME, MIME, and MTOM attachment and also be used for xsd:base64Binary
type values:
When the id
, type
, or options
members are non-NULL, an attachment will be used instead of base64 XML content. DIME attachments are the default. To switch to MIME use the SOAP_ENC_MIME
context flag. To switch to MTOM use the SOAP_ENC_MTOM
context flag.
MTOM is typically used with XOP <xop:Include>
elements, which is preferred and declared as follows:
Attachments are beyond the scope of this article. See the gSOAP user guide. for more details.
A class or struct with the following layout is a complexType that wraps simpleContent:
The type T
is a primitive type (bool
, enum
, time_t
, numeric and string types), xsd__hexBinary
, xsd__base64Binary
, and custom serializers, such as xsd__dateTime
.
This maps to a complexType with simpleContent in the soapcpp2-generated XML schema:
A wrapper class/struct may include any number of members that are declared as attributes with @
, which should be placed after the __item
member.
Use of a DOM is optional and enabled by #import "dom.h"
to use the DOM xsd__anyType
element node and xsd__anyAttribute
attribute node:
where name
contains XML stored in a DOM node set and attributes
is a list of all visibly rendered attributes. The name attributes
is arbitrary and any name will suffice.
You should place the xsd__anyType
members at the end of the struct or class. This ensures that the DOM members are populated last as a "catch all". A member name starting with double underscore is a wildcard member. These members are placed at the end of a struct or class automatically by soapcpp2.
An #import "dom.h"
import is automatically added by wsdl2h -d
with option -d
to bind xsd:anyType
to DOM nodes, and also to populate xsd:any
, xsd:anyAttribute
and xsd:mixed
XML content:
where the members prefixed with __
are "invisible" to the XML parser, meaning that these members are not bound to XML tag names.
In C you can use a dynamic arrary instead of std::vector
:
Classes can inherit DOM, which enables full use of polymorphism with one base DOM class:
This permits an xsd__anyType
pointer to refer to a derived class such as ns__record
, which will be serialized with an xsi:type
attribute that is set to "ns:record". The xsi:type
attributes add the necessary type information to distinguish the XML content from the DOM base type. This is important for the receiving end: without xsd:type
attributes with type names, only base DOM objects are recognized and instantiated.
Because C lacks object-oriented programming concepts such as class inheritance and polymorphism, you should consider using derived types in C and C++.
An alternative is to use the special tagged void pointer members to serialize data pointed to by a void*
member, which can be any serializable type, such as derived types. This approach uses xsi:type
attributes to identify the type of value serialized.
To ensure that wsdl2h generates pointer-based xsd__anyType
DOM nodes with wsdl2h -d
using option -d
for xsd:any
, add the following line to typemap.dat
:
xsd__any = | xsd__anyType*
This lets wsdl2h produce class/struct members and containers with xsd__anyType*
for xsd:any
instead of xsd__anyType
. To just force all xsd:anyType
uses to be pointer-based, declare in typemap.dat
:
xsd__anyType = | xsd__anyType*
If you use wsdl2h -d -p
using options -d
and -p
then every class will inherit DOM as shown above. Without option -d
, an xsd__anyType
type is generated to serve as the root type in the type hierarchy:
where the _XML __item
member holds any XML content as a literal XML string.
To use the DOM API, compile dom.c
(or dom.cpp
for C++), or link the gSOAP library with -lgsoapssl
(or -lgsoapssl++
for C++).
You can use //gsoap
directives in the interface header file with the data binding interface for soapcpp2. These directives are used to configure the code generated by soapcpp2 by declaring various. properties of Web services and XML schemas. When using the wsdl2h tool, you will notice that wsdl2h generates directives automatically based on the WSDL and XSD input.
Service directives are applicable to service and operations described by WSDL. Schema directives are applicable to types, elements, and attributes defined by XML schemas.
A service directive must start at a new line and is of the form:
where <prefix>
is the XML namespace prefix of a service binding. The <property>
and <value>
fields are one of the following:
property | value |
---|---|
name | name of the service, optionally followed by text describing the service |
namespace | URI of the WSDL targetNamespace |
documentation | text describing the service (see also the name property), multiple permitted |
doc | an alias for the documentation property |
style | document (default) SOAP messaging style or rpc for SOAP RPC |
encoding | literal (default), encoded for SOAP encoding, or a custom URI |
protocol | specifies SOAP or REST, see below |
port | URL of the service endpoint, usually an http or https address, to use in the WSDL definitions/service/port/address/@location |
location | an alias for the port property |
endpoint | an alias for the port property |
transport | URI declaration of the transport, usually http://schemas.xmlsoap.org/soap/http |
definitions | name of the WSDL definitions/@name |
type | name of the WSDL definitions/portType/@name (WSDL2.0 interface/@name) |
portType | an alias for the type property (portType follows SOAP 1.1 naming conventions) |
interface | an alias for the type property (interface follows SOAP 1.2 naming conventions) |
binding | name of the WSDL definitions/binding/@name |
portName | name of the WSDL definitions/service/port/@name |
executable | name of the "executable" to use in the WSDL definitions/service/port/address/@location |
The service name
and namespace
properties are required in order to generate a valid WSDL with soapcpp2. The other properties are optional.
The style
and encoding
property defaults are changed with soapcpp2 -e
option -e
to rpc
and encoded
, respectively.
The protocol
property is SOAP
by default (SOAP 1.1). Protocol property values are:
protocol value | description |
---|---|
SOAP | SOAP transport, supporting both SOAP 1.1 and 1.2 |
SOAP1.1 | SOAP 1.1 transport (same as soapcpp2 -1 ) |
SOAP1.2 | SOAP 1.2 transport (same as soapcpp2 -2 ) |
SOAP-GET | one-way SOAP 1.1 or 1.2 with HTTP GET |
SOAP1.1-GET | one-way SOAP 1.1 with HTTP GET |
SOAP1.2-GET | one-way SOAP 1.2 with HTTP GET |
HTTP | non-SOAP REST protocol with HTTP POST |
POST | non-SOAP REST protocol with HTTP POST |
GET | non-SOAP REST protocol with HTTP GET |
PUT | non-SOAP REST protocol with HTTP PUT |
DELETE | non-SOAP REST protocol with HTTP DELETE |
You can bind service operations to the WSDL namespace of a service by using the namespace prefix as part of the identifier name of the function that defines the service operation:
You can override the port
endpoint URL at runtime in the auto-generated soap_call_prefix__func
service call (C/C++ client side) and in the C++ proxy class service call.
Service properties are applicable to a service and to all of its operations. Service method directives are specifically applicable to a service operation.
A service method directive is of the form:
where <prefix>
is the XML namespace prefix of a service binding and <method>
is the unqualified name of a service operation. The <property>
and <value>
fields are one of the following:
method property | value |
---|---|
method-documentation | text describing the service operation |
method | an alias for the method-documentation property |
method-action | "" or URI SOAPAction HTTP header, or URL query string for REST protocols |
method-input-action | "" or URI SOAPAction HTTP header of service request messages |
method-output-action | "" or URI SOAPAction HTTP header of service response messages |
method-fault-action | "" or URI SOAPAction HTTP header of service fault messages |
method-header-part | member name of the SOAP_ENV__Header struct used in SOAP Header |
method-input-header-part | member name of the SOAP_ENV__Header struct used in SOAP Headers of requests |
method-output-header-part | member name of the SOAP_ENV__Header struct used in SOAP Headers of responses |
method-fault | type name of a struct or class member used in SOAP_ENV__Details struct |
method-mime-type | REST content type or SOAP MIME attachment content type(s) |
method-input-mime-type | REST content type or SOAP MIME attachment content type(s) of request message |
method-output-mime-type | REST content type or SOAP MIME attachment content type(s) of response message |
method-style | document or rpc |
method-encoding | literal , encoded , or a custom URI for encodingStyle of messages |
method-response-encoding | literal , encoded , or a custom URI for encodingStyle of response messages |
method-protocol | SOAP or REST, see service directives |
The method-header-part
properties can be repeated for a service operation to declare multiple SOAP Header parts that the service operation requires. You can use method-input-header-part
and method-output-header-part
to differentiate between request and response messages.
The method-fault
property can be repeated for a service operation to declare multiple faults that the service operation may return.
The method-action
property serves two purposes:
?
) to complete the service endpoint URL or extends the endpoint URL with a local path (starts with a /
).Use method-input-action
and method-output-action
to differentiate the SOAPAction between SOAP request and response messages.
You can always override the port endpoint URL and action values at runtime in the auto-generated soap_call_prefix__func
service call (C/C++ client side) and in the auto-generated C++ proxy class service calls. A runtime NULL endpoint URL and/or action uses the defaults set by these directives.
The method-mime-type
property serves two purposes:
application/x-www-form-urlencoded
with REST POST and PUT protocols to send encoded form data automatically instead of XML. Only primitive type values can be transmitted with form data, such as numbers and strings, i.e. only types that are legal to use as attributes members.Use method-input-mime-type
and method-output-mime-type
to differentiate the attachment types between request and response messages.
A schema directive is of the form:
where <prefix>
is the XML namespace prefix of a schema. The <property>
and <value>
fields are one of the following:
property | value |
---|---|
namespace | URI of the XSD targetNamespace |
namespace2 | alternate URI pattern for the XSD namespace (i.e. URI is also accepted by the XML parser) |
import | URI of an imported namespace, as an alternative or in addition to namespace , adds xsd:import to the generated WSDL and XSD files |
form | unqualified (default) or qualified local element and attribute form defaults |
elementForm | unqualified (default) or qualified local element form default |
attributeForm | unqualified (default) or qualified local attribute form default |
typed | no (default) or yes for serializers to add xsi:type attributes to XML |
To learn more about the local form defaults, see qualified and unqualified members.
The namespace2
URI is a pattern with *
matching any sequence of characters and -
matching any character. This pattern instructs the XML parser and validator to also accept the URI pattern as a valid namespace for the specified <prefix>
.
The typed
property is implicitly yes
when soapcpp2 -t
option -t
is used.
A schema type directive is of the form:
where <prefix>
is the XML namespace prefix of a schema and <name>
is an unqualified name of a C/C++ type, and the optional <member>
is a class/struct members or enum constant.
You can describe a type with one of the following:
type property | value |
---|---|
type-documentation | text describing the schema type |
type | an alias for the type-documentation property |
For example, you can add a description to an enumeration:
This documented enumeration maps to a simpleType restriction of xsd:string
in the soapcpp2-generated schema:
A presentation on XML data bindings is not complete without discussing the serialization rules and options that put your data in XML on the wire or store it a file or buffer.
There are several options to choose from to serialize data in XML. The choice depends on the use of the SOAP protocol or if SOAP is not required. The wsdl2h tool automates this for you by taking the WSDL transport bindings into account when generating the service functions in C and C++ that use SOAP or REST.
The gSOAP tools are not limited to SOAP. The tools implement generic XML data bindings for SOAP, REST, and other uses of XML. So you can read and write XML using the serializing operations on classes and structs.
The following sections briefly explain the serialization rules with respect to the SOAP protocol for XML Web services. A basic understanding of the SOAP protocol is useful when developing client and server applications that must interoperate with other SOAP applications.
SOAP/REST Web service client and service operations are represented as functions in your interface header file with the data binding interface for soapcpp2. The soapcpp2 tool will translate these function to client-side service invocation calls and server-side service operation dispatchers.
A discussion of SOAP clients and servers is beyond the scope of this article. However, the SOAP options discussed here also apply to SOAP client and server development.
The wsdl:binding/soap:binding/@style
attribute in the <wsdl:binding>
section of a WSDL is either "document" or "rpc". The "rpc" style refers to SOAP RPC (Remote Procedure Call), which is more restrictive than the "document" style by requiring one XML element in the SOAP Body to act as the procedure name with XML subelements as its parameters.
For example, the following directives in the interface header file for soapcpp2 declare that DBupdate
is a SOAP RPC encoding service method:
The XML payload has a SOAP envelope, optional SOAP header, and a SOAP body with one element representing the operation with the parameters as subelements:
The "document" style puts no restrictions on the SOAP Body content. However, we recommend that the first element's tag name in the SOAP Body should be unique to each type of operation, so that the receiver can dispatch the operation based on this element's tag name. Alternatively, the HTTP URL path can be used to specify the operation, or the HTTP action header can be used to dispatch operations automatically on the server side (soapcpp2 options -a and -A).
The wsdl:operation/soap:body/@use
attribute in the <wsdl:binding>
section of a WSDL is either "literal" or "encoded". The "encoded" use refers to the SOAP encoding rules that support id-ref multi-referenced elements to serialize data as graphs.
SOAP encoding is very useful if the data internally forms a graph (including cycles) and we want the graph to be serialized in XML in a format that ensures that its structure is preserved. In that case, SOAP 1.2 encoding is the best option.
SOAP encoding also adds encoding rules for SOAP arrays to serialize multi-dimensional arrays. The use of XML attributes to exchange XML data in SOAP encoding is not permitted. The only attributes permitted are the standard XSD attributes, SOAP encoding attributes (such as for arrays), and id-ref.
For example, the following directives in the interface header file for soapcpp2 declare that DBupdate
is a SOAP RPC encoding service method:
The XML payload has a SOAP envelope, optional SOAP header, and a SOAP body with an encodingStyle attribute for SOAP 1.1 encoding and an element representing the operation with parameters that are SOAP 1.1 encoded:
In the XML fragment shown above the name "Joe" is shared by two records and the string is referenced by SOAP 1.1 href and id attributes.
While the soapcpp-generated serializers only introduce multi-referenced elements in the payload when they are actually multi-referenced in the data graph, other SOAP applications may render multi-referenced elements more aggressively. The example could also be rendered as:
SOAP 1.2 encoding is cleaner and produces more accurate XML encodings of data graphs by setting the id attribute on the element that is referenced:
SOAP-ENC
of SOAP-ENC:id
and SOAP-ENC:ref
optional. With gSOAP, the SOAP 1.2 encoding serialization follows the 2007 standard, while accepting unqualified id and ref attributes.To remove all rendered id-ref multi-referenced elements, use the SOAP_XML_TREE
flag to initialize the soap
context.
Some XSD validation rules are turned off with SOAP encoding, because of the presence of additional attributes, such as id and ref/href, SOAP arrays with arbitrary element tags for array elements, and the occurrence of additional multi-ref elements in the SOAP 1.1 Body.
The use of "literal" puts no restrictions on the XML in the SOAP Body. Full XSD validation is possible, which can be enabled with the SOAP_XML_STRICT
flag to initialize the soap
context. However, data graphs will be serialized as trees and cycles in the data will be cut from the XML rendition.
There are two SOAP protocol versions: 1.1 and 1.2. The gSOAP tools can switch between the two versions seamlessly. You can declare the default SOAP version for a service operation as follows:
Use SOAP
(SOAP 1.1), SOAP1.1
, SOAP1.2
, and HTTP
to switch SOAP versions or enable REST methods with HTTP POST. See service directives and XML serialization.
The soapcpp2 tool auto-generates client and server code. At the client side, this operation sends data with SOAP 1.2 but accepts responses also in SOAP 1.1. At the server side, this operation accepts requests in SOAP 1.1 and 1.2 and will return responses in the same SOAP version.
As we discussed in the previous section, the SOAP 1.2 protocol has a cleaner multi-referenced element serialization format that greatly enhances the accuracy of data graph serialization with SOAP RPC encoding and is therefore recommended.
The SOAP 1.2 protocol default can also be set by importing and loading gsoap/import/soap12.h
:
Finally, the soapcpp2 tool has options to force SOAP 1.1, SOAP 1.2, or remove SOAP altogether with soapcpp2 -1
(SOAP 1.1), soapcpp2 -2
(SOAP 1.2) and soapcpp2 -0
(plain XML, no SOAP).
You can serialize data to XML that is stored on the heap, on the stack (locals), and static data as long as the serializable (i.e. non-transient) values are properly initialized and pointers in the data structures are either NULL or point to valid structures.
When XML is deserialized into data, the data is put on the heap and managed by the ::soap
context, see also memory management.
You can read and write XML directly to a file or stream with the serializing operations on classes and structs.
To define and use XML Web service client and service operations, we can declare these operations in your interface header file with the data binding interface for soapcpp2 as functions. The function are translated by soapcpp2 to client-side service invocation calls and server-side service operation dispatchers.
The REST operations POST, GET, and PUT are declared with //gsoap
directives in the interface header file for soapcpp2. For example, a REST HTTP POST operation is declared as follows:
There are no SOAP Envelope and SOAP Body elements in the payload for DBupdate
. Also the XML serialization rules are identical to SOAP document/literal, meaning no SOAP RPC encoding XML structures are implicitly used. The XML payload only has the operation name as an element with its parameters serialized as subelements:
To force id-ref serialization with REST similar to SOAP 1.2 multi-reference encoding, use the SOAP_XML_GRAPH
flag to initialize the soap
context. The XML serialization includes id and ref attributes for multi-referenced elements as follows:
Reading and writing XML from/to files, streams and string buffers is done via the managing soap
context by setting one of the following context variables that control IO sources and sinks:
Normally, all of these context variables are NULL, which is required to send and receive data over sockets by gSOAP client and server applications. Therefore, if you set any of these context variables in a client or server application then you should reset them to NULL to ensure that socket communications are not blocked.
soap::is
and soap::os
in C requires gSOAP 2.8.28 or greater.In the following sections, we present more details on how to read and write to files and streams, and use string buffers as sources and sinks for XML data.
In addition, you can set IO callback functions to handle IO at a lower level. For more details on defining your own callback functions, see the gSOAP user guide.
The default IO is standard input and output. Other sources and sinks (those listed above) will be used until you (re)set them. For example with file-based input and output:
Similar code with streams in C++:
For C++ we recommend to use std::stringstream
objects from the sstream
C++ library as illustrated in the following example:
For C we can use soap::is
and soap::os
to point to strings of XML content as follows (this requires gSOAP 2.8.28 or later):
The type of soap::os
is a pointer to a const char*
string. The pointer is set by the managing soap
context to point to the XML data that is stored on the context-managed heap.
For earlier gSOAP versions we recommend to use IO callbacks soap::frecv
and soap::fsend
, see the gSOAP user guide..
Memory management with the soap
context enables us to allocate data in context-managed heap space that can be collectively deleted. All deserialized data is placed on the context-managed heap by the soap
context of the engine.
When working with gSOAP in C (i.e. using wsdl2h -c
option -c
or soapcpp2 -c
option -c
), data is allocated on the managed heap with:
void *soap_malloc(struct soap*, size_t len)
.This function allocates len
bytes on the heap managed by the specified context and returns NULL when allocation failed.
You can also make shallow copies of data with soap_memdup
that uses soap_malloc
and a safe version of memcpy
to copy a chunk of data src
with length len
to the context-managed heap:
void * soap_memdup(struct soap*, const void *src, size_t len)
This function returns a pointer to the copy. This function requires gSOAP 2.8.27 or later.
In gSOAP 2.8.35 and greater versions, you can use an auto-generated function to allocate and initialize data of type T
on the managed heap:
T * soap_new_T(struct soap*, int n)
This function returns an array of length n
of type T
data that is default initialized (by internally calling soap_malloc(soap, n * sizeof(T))
and then soap_default_T(soap, T*)
on each array value). Use a negative value or n=1
to allocate and initialize a single value. This function returns NULL when allocation failed.
The soap_malloc
function is essentially a wrapper around malloc
, but permits the soap
context to track all heap allocations for collective deletion with soap_end(soap)
:
All data on the managed heap is mass-deleted with soap_end(soap)
which must be called before soap_done(soap)
or soap_free(soap)
, which end the use of the soap
context and free the context, respectively. Use soap_free(soap)
only when the context is allocated with soap_new()
. Use soap_done(soap)
only when the context is stack allocated (so cannot be deleted from the heap).
The managed heap is checked for memory leaks at run time when the source code is compiled with option -DDEBUG
.
The soapcpp2 auto-generated deserializers in C use soap_malloc
to allocate and populate deserialized structures, which are managed by the context for collective deletion.
To make char*
and wchar_t*
string copies to the context-managed heap, we can use the functions:
char *soap_strdup(struct soap*, const char *str)
andwchar_t *soap_wstrdup(struct soap*, const wchar_t *wstr)
.If your C compiler supports typeof
then you can use the following macro to simplify the managed heap allocation and initialization of primitive values:
Pointers to primitive values are often used for optional members. For example, assume we have the following struct:
Use soap_assign
to create a SSN value on the managed heap:
Without the soap_assign
macro, you will need two lines of code, one to allocate and one to assign (you should also use this if your system can run out of memory):
The serializer can serialize any heap, stack, or static allocated data. So we can also create a new record as follows:
Use the soapcpp2 auto-generated soap_dup_T
functions to duplicate data into another soap
context (this requires soapcpp2 -Ec
option -Ec
to generate), here shown for C with the second argument dst
NULL because we want to allocate a new managed structure:
The only reason to use another soap
context and not to use the primary soap
context is when the primary context must be destroyed together with all of the objects it manages while some of the objects must be kept alive. If the objects that are kept alive contain deep cycles then this is the only option we have, because deep copy with a managing soap
context detects and preserves these cycles unless the SOAP_XML_TREE
flag is used with the soap
context:
The resulting deep copy will be a full copy of the source data structure as a tree without co-referenced data (i.e. no digraph) and without cycles. Cycles are pruned and (one of the) pointers that forms a cycle is repaced by NULL.
You can also deep copy into unmanaged space and use the auto-generated soap_del_T()
function (requires soapcpp2 -Ed
option -Ed
to generate) to delete it later:
But you should not do this for any data that has deep cycles in its runtime data structure. Cycles in the data structure will lead to non-termination when making unmanaged deep copies. Consider for example:
The code to populate a structure with a mutual spouse relationship:
The bad case is where there is no context used in the first argument. The deep copy functions use a context to keep track of co-referenced data nodes and cycles in the data structure copies, to copy co-referenced nodes just once. Co-references in a data structure are formed by pointers and smart pointers such as std::shared_ptr
, such that at least two pointers point to the same data.
The serializer can serialize any heap, stack, or static allocated data, such as in the code shown above. So we can serialize the stack-allocated pers1
record as follows:
which produces an XML document record.xml that is similar to:
Deserialization of an XML document with a SOAP 1.1/1.2 encoded id-ref graph leads to the same non-termination problem when we later try to copy the data into unmanaged memory heap space:
Copying data with soap_dup_T(soap)
into managed heap memory space is always safe. Copying into unmanaged heap memory space requires diligence. But deleting unmanaged data is easy with soap_del_T()
.
You can also use soap_del_T()
to delete structures that you created in C, but only if these structures are created with malloc
and do NOT contain pointers to stack and static data.
You can unlink one or more allocated objects from the managed heap to allow the object to live after soap_end(soap)
by using:
void soap_unlink(struct soap *soap, void *ptr)
The unlinked heap-allocated data pointed to by ptr
can be accessed after soap_end(soap)
. Do not forget to free the data with free(ptr)
. Be aware that soap_unlink(soap, ptr)
does not perform a deep unlinkage. If ptr
is a struct, pointer members will become invalid when pointing to objects on the managed heap. Use soap_unlink(soap, ptr->member)
to unlink member
as well.
Finally, when data is allocated in managed memory heap space, either explicitly with the allocation functions shown above or by the soapcpp2-generated deserializers, you can delegate the management and deletion of this data to another soap
context. That context will be responsible to delete the data with soap_end(soap)
later:
void delegate_deletion(struct soap *soap_from, struct soap *soap_to)
This allows the soap_from
context to be deleted with soap_free(soap_from)
(assuming it is allocated with soap_new()
, use soap_done(soap_from)
when soap_from
is stack-allocated) while the managed data remains intact. You can use this function any time, to delegate management and deletion to another context soap_to
and then continue with the current context. You can also use different source soap_from
contexts to delegate management and deletion to the other soap_to
context. To mass delete all managed data, use soap_end(soap_to)
.
When working with gSOAP in C++, the engine allocates data on a managed heap using soap_new_T(soap)
to allocate a type with type name T
. Managed heap allocation is tracked by the soap
context for collective deletion with soap_destroy(soap)
for structs, classes, and templates and with soap_end(soap)
for everything else.
You should only use soap_malloc(struct soap*, size_t len)
to allocate primitive types because constructors are not invoked. Therefore, soap_new_T
is preferred. The auto-generated T * soap_new_T(struct soap*)
returns data allocated on the managed heap for type T
. The data is mass-deleted with soap_destroy(soap)
followed by soap_end(soap)
.
The soap_new_T
functions return NULL when allocation fails. C++ exceptions are never raised by the engine and serializers when data is allocated.
There are four variations of soap_new_T
functions to allocate data of type T
that soapcpp2 auto-generates:
T * soap_new_T(struct soap*)
returns a new instance of T
that is default initialized. For classes, initialization is internally performed using the soapcpp2 auto-generated void T::soap_default(struct soap*)
method of the class, but ONLY IF the soapcpp2 auto-generated default constructor is used that invokes soap_default()
and was not replaced by a user-defined default constructor.T * soap_new_T(struct soap*, int n)
returns an array of n
new instances of T
. The instances in the array are default initialized as described above.T * soap_new_req_T(struct soap*, ...)
(structs and classes only) returns a new instance of T
and sets the required data members to the values specified in ...
. The required data members are those with nonzero minOccurs, see the subsections on (smart) pointer members and their occurrence constraints and container and array members and their occurrence constraints.T * soap_new_set_T(struct soap*, ...)
(structs and classes only) returns a new instance of T
and sets the public/serializable data members to the values specified in ...
.The above functions can be invoked with a NULL soap
context, but you are then responsible to use delete T
to remove this instance from the unmanaged heap.
For example, to allocate a managed std::string
you can use:
To throw a std::bad_alloc
exception when memory allocation fails, we can define the following class and macro:
And use CHECK
as follows to throw an exception when memory allocation fails:
To throw a std::runtime_exception
when memory allocation fails, with file and line number information where the error occurred, we can define the following revised version of our exception-throwing macro:
And use CHECK
as follows to throw an exception with the file and line number of the location where memory allocation failed:
Primitive types and arrays of primitive values may be allocated with soap_malloc
(actually, soap_new_T
calls soap_malloc
for primitive type T
). All primitive types (i.e. no classes, structs, class templates, containers, and smart pointers) are allocated with soap_malloc
for reasons of efficiency.
You can use a C++ template to simplify the managed allocation and initialization of primitive values as follows (this is for primitive types only):
For example, assuming we have the following class:
You can instantiate a record by using the auto-generated soap_new_set_ns__record
and use soap_make
to create a SSN value on the managed heap as follows:
All data on the managed heap is mass-deleted with soap_end(soap)
which must be called before soap_done(soap)
or soap_free(soap)
, which end the use of the soap
context and free the context, respectively. Use soap_free(soap)
only when the context is allocated with soap_new()
. Use soap_done(soap)
only when the context is stack allocated (so cannot be deleted from the heap).
The managed heap is checked for memory leaks at run time when the source code is compiled with option -DDEBUG
.
However, the serializer can serialize any heap, stack, or static allocated data. So we can also create a new record as follows:
which will be fine to serialize this record as long as the local SSN
stack-allocated value remains in scope when invoking the serializer and/or using record
. It does not matter if soap_destroy
and soap_end
are called beyond the scope of SSN
.
To facilitate class methods to access the managing context, we can add a soap context pointer to a class/struct:
The soap
context pointer member of the class is set when invoking soap_new_T
(and similar) with a non-NULL context argument that will be assigned to the soap
member of the class.
You can also use a template when an array of pointers to values is required. To create an array of pointers to values, define the following template:
The array
parameter is a pointer to an array of n
values. The template returns an array of n
pointers that point to the values in that array:
Note that soap_new_ns__record(soap, n)
returns a pointer to an array of n
records, which is then used to create an array of n
pointers to these records.
Use the soapcpp2 auto-generated soap_dup_T
functions to duplicate data into another soap
context (this requires soapcpp2 -Ec
option -Ec
to generate), here shown for C++ with the second argument dst
NULL to allocate a new managed object:
To duplicate base and derived instances when a base class pointer or reference is provided, use the auto-generated method T * T::soap_dup(struct soap*)
:
The only reason to use another context and not to use the primary soap
context is when the primary context must be destroyed together with all of the objects it manages while some of the objects must be kept alive. If the objects that are kept alive contain deep cycles then this is the only option we have, because deep copy with a managing soap
context detects and preserves these cycles unless the SOAP_XML_TREE
flag is used with the context:
The resulting deep copy will be a full copy of the source data structure as a tree without co-referenced data (i.e. no digraph) and without cycles. Cycles are pruned and (one of the) pointers that forms a cycle is repaced by NULL.
You can also deep copy into unmanaged space and use the auto-generated soap_del_T()
function or the T::soap_del()
method (requires soapcpp2 -Ec
option -Ec
to generate) to delete it later, but we should not do this for any data that has deep cycles in its runtime data structure graph:
Cycles in the data structure will lead to non-termination when making unmanaged deep copies. Consider for example:
The code to populate a structure with a mutual spouse relationship:
The serializer can serialize any heap, stack, or static allocated data, such as shown in the code shown above. So we can serialize the stack-allocated pers1
record as follows:
which produces an XML document record.xml that is similar to:
Deserialization of an XML document with a SOAP 1.1/1.2 encoded id-ref graph leads to the same non-termination problem when we later try to copy the data into unmanaged space:
Copying data with soap_dup_T(soap)
into managed space is always safe. Copying into unmanaged space requires diligence. But deleting unmanaged data is easy with soap_del_T()
.
You can also use soap_del_T()
to delete structures in C++, but only if these structures are created with new
(and new []
for arrays when applicable) for classes, structs, and class templates and with malloc
for anything else, and the structures do NOT contain pointers to stack and static data.
You can unlink one or more allocated objects from the managed heap to allow the object to live after soap_destroy(soap)
and soap_end(soap)
by using:
void soap_unlink(struct soap *soap, void *ptr)
The unlinked heap-allocated data pointed to by ptr
can be accessed after soap_destroy(soap)
and soap_end(soap)
. Do not forget to free the data with delete ptr
(C++ class instance only) or with free(ptr)
(non-class data). Be aware that soap_unlink(soap, ptr)
does not perform a deep unlinkage. If ptr
is a struct or class, pointer members will become invalid when pointing to objects on the managed heap. Use soap_unlink(soap, ptr->member)
to unlink member
as well.
Finally, when data is allocated in managed memory heap space, either explicitly with the allocation functions shown above or by the soapcpp2-generated deserializers, you can delegate the management and deletion of this data to another soap
context. That context will be responsible to delete the data with soap_destroy(soap)
and soap_end(soap)
later:
void delegate_deletion(struct soap *soap_from, struct soap *soap_to)
This allows the soap_from
context to be deleted with soap_free(soap_from)
(assuming it is allocated with soap_new()
, use soap_done(soap_from)
when soap_from
is stack-allocated) while the managed data remains intact. You can use this function any time, to delegate management and deletion to another context soap_to
and then continue with the current context. You can also use different source soap_from
contexts to delegate management and deletion to the other soap_to
context. To mass delete all managed data, use soap_destroy(soap_to)
followed by soap_end(soap_to)
.
There are several soap
context initialization flags and context mode flags to control XML serialization at runtime. The flags are set with soap_new1()
to allocate and initialize a new context:
and with soap_init1()
for stack-allocated contexts:
where flag1
, flag2
, ..., flagn
is one of:
SOAP_C_UTFSTRING
: enables all std::string
and char*
strings to contain UTF-8 content. This option is recommended.SOAP_C_NILSTRING
: treat empty strings as if they were NULL pointers, i.e. omits elements and attributes when empty.SOAP_XML_STRICT
: strictly validates XML while deserializing. Should not be used together with SOAP 1.1/1.2 encoding style of messaging. Use soapcpp2 -s
option -s
to hard code SOAP_XML_STRICT
in the generated serializers. Not recommended with SOAP 1.1/1.2 encoding style messaging.SOAP_XML_INDENT
: produces indented XML.SOAP_XML_CANONICAL
: c14n canonocalization, removes unused xmlns
bindings and adds them to appropriate places by applying c14n normalization rules. Should not be used together with SOAP 1.1/1.2 encoding style messaging.SOAP_XML_TREE
: write tree XML without id-ref, while pruning data structure cycles to prevent nontermination of the serializer for cyclic structures.SOAP_XML_GRAPH
: write graph (digraph and cyclic graphs with shared pointers to objects) using id-ref attributes. That is, XML with SOAP multi-ref encoded id-ref elements. This is a structure-preserving serialization format, because co-referenced data and also cyclic relations are accurately represented.SOAP_XML_DEFAULTNS
: uses xmlns default namespace declarations, assuming that the schema attribute form is "qualified" by default (be warned if it is not, since attributes in the null namespace will get bound to namespaces!).SOAP_XML_NIL
: emit empty element with xsi:nil
for all NULL pointers serialized.SOAP_XML_IGNORENS
: the XML parser ignores XML namespaces, i.e. element and attribute tag names match independent of their namespace.SOAP_XML_NOTYPE
: removes all xsi:type
attribuation. This option is usually not needed unless the receiver rejects all xsi:type
attributes. This option may affect the quality of the deserializer, which relies on xsi:type
attributes to distinguish base class instances from derived class instances transported in the XML payloads.SOAP_IO_CHUNK
: to enable HTTP chunked transfers.SOAP_IO_STORE
: full buffering of outbound messages.SOAP_ENC_ZLIB
: compress messages, requires compiling with option -DWITH_GZIP
and linking with zlib using option -lz
.SOAP_ENC_MIME
: enable MIME attachments, see DIME/MIME/MTOM attachment binary types.SOAP_ENC_MTOM
: enable MTOM attachments, see DIME/MIME/MTOM attachment binary types.soap
context, either as a base class (with soapcpp2 -i
option -i
) or as a pointer member soap
that points to a context (with soapcpp2 -j
option -j
). These contexts are allocated when the proxy or service is instantiated with context flags that are passed to the constructor.After allocation and initializtion of a soap
context, several context parameters can be set (some parameters may require 2.8.31 or greater):
unsigned int soap::maxlevel
is the maximum XML nesting depth levels that the parser permits. Default initialized to SOAP_MAXLEVEL
(10000), which is a redefinable macro in gsoap/stdsoap2.h
. Set soap::maxlevel
to a lower value to restrict XML parsing nesting depth.long soap::maxlength
is the maximum string content length if not already constrained by an XML schema validation maxLength
constraint. Zero means unlimited string lengths are permitted (unless restricted by XML schema maxLength
). Default initialized to SOAP_MAXLENGTH
(0), which is a redefinable macro in gsoap/stdsoap2.h
. Set soap::maxlength
to a positive value to restrict the number of (wide) characters in strings parsed, restrict hexBinary byte length, and restrict base64Binary byte length.size_t soap::maxoccurs
is the maximum number of array or container elements permitted by the parser. Must be greater than zero (0). Default initialized to SOAP_MAXOCCURS
(100000), which is a redefinable macro in gsoap/stdsoap2.h
. Set soap::maxoccurs
to a positive value to restrict the number of array and container elements that can be parsed.soap::version
is the SOAP version used, with 0 for non-SOAP, 1 for SOAP1.1, and 2 for SOAP1.2. This value is normally set by web service operations, and is otherwise 0 (non-SOAP). Use soap_set_version(struct soap*, short)
to set the value. This controls XML namespaces and SOAP id-ref serialization when applicable with an encodingStyle (see below).const char *soap::encodingStyle
is a string that is used with SOAP encoding, normally NULL for non-SOAP XML. Set this string to "" (empty string) to enable SOAP encoding style, which supports id-ref graph serialization (see also the SOAP_XML_GRAPH
context flag).int soap::recvfd
is the file descriptor to read and parse source data from. Default initialized to 0 (stdin). See also input and output.int soap::sendfd
is the file descriptor to write data to. Default initialized to 1 (stdout). See also input and output.const char *is
for C: string to read and parse source data from, overriding the recvfd
source. Normally NULL. This value must be reset to NULL or the parser will continue to read from this string content until the NUL character. See also input and output.std::istream *is
for C++: an input stream to read and parse source data from, overriding the recvfd
source. Normally NULL. This value must be reset to NULL or the parser will continue to read from this stream until EOF. See also input and output.const char **os
for C: points to a string (a const char *
) that will be set to point to the string output. Normally NULL. This value must be reset to NULL or the next output will result in reassigning the pointer to point to the next string that is output. The strings are automatically deallocated by soap_end(soap)
. See also input and output.std::ostream *os
for C++: an output stream to write output to. Normally NULL. This value must be reste to NULL or the next output will be send to this stream. See also input and output.The gSOAP API functions return SOAP_OK
(zero) or a non-zero error code. The error code is stored in int soap::error
of the current soap
context. Error messages can be displayed with:
void soap_stream_fault(struct soap*, std::ostream &os)
for C++ only, prints the error message to an output stream.void soap_print_fault(struct soap*, FILE *fd)
prints the error message to a FILE descriptor.void soap_sprint_fault(struct soap*, char *buf, size_t len)
saves the error message to a fixed-size buffer allocated with a maximum length.void soap_print_fault_location(struct soap*, FILE *fd)
prints the location and part of the XML where the parser encountered an error.C++ exceptions are never raised by the engine or serializers, even when data is allocated.
A SOAP_EOM
error code is returned when memory was exhausted during processing of input and/or output of data.
An EOF (SOAP_EOF
or -1) error code is returned when the parser has hit EOF but expected more input, or when socket communications timed out. In addition to the SOAP_EOF
error, the int soap::errnum
of the soap
context is set to the errno
value of the operation that failed. For timeouts, the soap::ernum
value is always 0 instead of an errno
error code.
Use soap_xml_error_check(soap->error)
to check for XML errors. This returns true (non-zero) when a parsing and validation error has occurred.
For example:
When deploying your application on UNIX and Linux systems, UNIX signal handlers should be added to your code handle signals, in particular SIGPIPE
:
where the sigpipe_handler
is a function:
Other UNIX signals may have to be handled as well.
The engine is designed for easy memory cleanup after being interrupted. Use soap_destroy(soap)
and soap_end(soap)
, after which the soap
context can be reused.
In general, to use the generated code:
#include "soapH.h"
in your code and also define a namespace table or #include "ns.nsmap"
with the generated table, where ns
is the namespace prefix for services.soapcpp2 -j
option -j
(C++ only) to generate C++ proxy and service objects. The auto-generated files include documented inferfaces. Compile with soapC.cpp
and link with -lgsoap++
, or alternatively compile gsoap/stdsoap2.cpp
.soapcpp2 -j
option -j
: client-side uses the auto-generated soapClient.cpp
and soapC.cpp
(or C versions of those). Compile and link with -lgsoap++
(-lgsoap
for C), or alternatively compile gsoap/stdsoap2.cpp
(gsoap/stdsoap2.c
for C).soapcpp2 -j
option -j
: server-side uses the auto-generated soapServer.cpp
and soapC.cpp
(or C versions of those). Compile and link with -lgsoap++
(-lgsoap
for C), or alternatively compile gsoap/stdsoap2.cpp
(stdsoap2.c
for C).soap_new()
or soap_new1(int flags)
to allocate and initialize a heap-allocated soap
context with or without flags. Delete this soap
context with soap_free(struct soap*)
, but only after soap_destroy(struct soap*)
and soap_end(struct soap*)
.soap_init(struct *soap)
or soap_init1(struct soap*, int flags)
to initialize a stack-allocated soap
context with or without flags. End the use of this context with soap_done(struct soap*)
, but only after soap_destroy(struct soap*)
and soap_end(struct soap*)
.Additional notes with respect to the wsdl2h and soapcpp2 tools:
#import "file.h"
instead of #include
to import other header files in a interface header file for soapcpp2. The #include
, #define
, and #pragma
are accepted by soapcpp2, but are moved to the very start of the generated code for the C/C++ compiler to include before all generated definitions. Often it is useful to add an #include
with a volatile type that includes the actual type declaration, and to ensure transient types are declared when these are used in a data binding interface declared in a interface header file for soapcpp2.soapcpp2 -0
option -0
.wsdl2h -qname
option -qname
to add C++ namespace name
. Or add a namespace name { ... }
to the header file, but the { ... }
must cover the entire header file content from begin to end.wsdl2h -d
option -d
for XML DOM support and compile and link with gsoap/dom.c
or gsoap/dom.cpp
. For details, see XML DOM and XPath.The soapcpp2 tool generates a .nsmap
file that includes two bindings for SOAP namespaces. We can remove all SOAP namespaces (and SOAP processing logic) with soapcpp2 -0
option -0
or by simply setting the two entries to NULL:
Once the .nsmap
is generated, you can copy-paste the content into your project code. However, if we rerun wsdl2h on updated WSDL/XSD files or typemap.dat
declarations then we need to use the updated table.
In cases that no XML namespaces are used at all, for example with XML-RPC, you may use an empty namespace table:
However, beware that any built-in xsi attributes that are rendered will lack the proper namespace binding. At least we suggest to use SOAP_XML_NOTYPE
for this reason.
Select the project files below to peruse the source code examples.
address.xsd
Address book schemaaddress.cpp
Address book app (reads/writes address.xml file)addresstypemap.dat
Schema namespace prefix name preference for wsdl2hgraph.h
Graph data binding (tree, digraph, cyclic graph)graph.cpp
Test graph serialization as tree, digraph, and cyclicaddress.h
data binding interface generated from address.xsdaddressStub.h
C++ data binding definitionsaddressH.h
SerializersaddressC.cpp
Serializersaddress.xml
Address book data generated by address appgraphStub.h
C++ data binding definitionsgraphH.h
SerializersgraphC.cpp
Serializersg.xsd
XSD schema with g:Graph
complexTypeg.nsmap
xmlns bindings namespace mapping tableBuilding the AddressBook example:
wsdl2h -g -taddresstypemap.dat address.xsd soapcpp2 -0 -C -S -paddress -I../../import address.h c++ -I../.. address.cpp addressC.cpp -o address -lgsoap++
Using wsdl2h -g -taddresstypemap.dat
option -g
produces bindings for global (root) elements in addition to types and option -taddresstypemap.dat
specifies a mapping file, see further below.
In this case the root element a:address-book
is bound to _a__address_book
. The complexType a:address
is bound to class a__address
, which is also the type of _a__address_book
. This option is not required, but allows you to use global element tag names when referring to their serializers, instead of their type name. Using soapcpp2 -0 -C -S -paddress
option -0
removes the SOAP protocol and the combination of the two options -C
and -S
removes client and server code generation (using option -C
alone generates client code and using option -S
alone generates server code). Option -paddress
renames the output soap
-prefixed files to address
-prefixed files.
See the address.cpp
implementation and related pages.
The addresstypemap.dat
file specifies the XML namespace prefix for the bindings:
# Bind the address book schema namespace to prefix 'a' a = "urn:address-book-example" # By default the xsd:dateTime schema type is translated to time_t # To map xsd:dateTime to struct tm, enable the following line: # xsd__dateTime = #import "../../custom/struct_tm.h" # ... and compile/link with custom/struct_tm.c
The DOB field is a xsd:dateTime
, which is bound to time_t
by default. To change this to struct tm
, enable the import of the xsd__dateTime
custom serializer by uncommenting the definition of xsd__dateTime
in addresstypemap.dat
. Then change soap_dateTime2s
to soap_xsd__dateTime2s
in the code.
Building the graph serialization example:
soapcpp2 -C -S -pgraph -I../../import graph.h c++ -I../.. graph.cpp graphC.cpp -o graph -lgsoap++
To compile without using the -lgsoap++
library: simply compile stdsoap2.cpp
together with the above.
To execute the AddressBook example:
./address
To execute the Graph serialization example:
./graph