• gSOAP

apt-get install gsoap

• gSOAP 2.7.9 User Guide
• gSOAP & Web Services

Let's see the server/client generation for a simple service: HelloService.

<?xml version="1.0" encoding="UTF-8"?>
<definitions name="HelloService"
   targetNamespace="http://www.emilmont.net/wsdl/HelloService.wsdl"
   xmlns="http://schemas.xmlsoap.org/wsdl/"
   xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/"
   xmlns:tns="http://www.emilmont.net/wsdl/HelloService.wsdl"
   xmlns:xsd="http://www.w3.org/2001/XMLSchema">
 
   <message name="SayHelloRequest">
      <part name="firstName" type="xsd:string"/>
   </message>
   <message name="SayHelloResponse">
      <part name="greeting" type="xsd:string"/>
   </message>
 
   <portType name="Hello_PortType">
      <operation name="sayHello">
         <input message="tns:SayHelloRequest"/>
         <output message="tns:SayHelloResponse"/>
      </operation>
   </portType>
 
   <binding name="Hello_Binding" type="tns:Hello_PortType">
      <soap:binding style="rpc" 
         transport="http://schemas.xmlsoap.org/soap/http"/>
      <operation name="sayHello">
         <soap:operation soapAction="sayHello"/>
         <input>
            <soap:body
               encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"
               namespace="urn:examples:helloservice"
               use="encoded"/>
         </input>
         <output>
            <soap:body 
               encodingStyle="http://schemas.xmlsoap.org/soap/encoding/"
               namespace="urn:examples:helloservice"
               use="encoded"/>
         </output>
      </operation>
   </binding>
 
   <service name="Hello_Service">
      <documentation>WSDL File for HelloService</documentation>
      <port binding="tns:Hello_Binding" name="Hello_Port">
         <soap:address location="http://localhost:8888"/>
      </port>
   </service>
</definitions>

The gSOAP release distribution package provides two compiler tools to develop your applications:

• The 'wsdl2h' WSDL parser.
• The 'soapcpp2' stub and skeleton compiler.

The 'wsdl2h' parser converts WSDL into gSOAP header file specifications of Web services. This specification gives a C/C++ transparent view of the server's functionality. The header file is processed by 'soapcpp2' to generate the source code stubs and skeletons to invoke the service or build a new service based on the WSDL.

wsdl2h -c HelloService.wsdl
soapcpp2 -c HelloService.h 

#include "soapH.h"
#include "Hello_USCOREBinding.nsmap" 
 
int main(int argc, char* argv[]) {
    int m, s;
    struct soap soap;
 
    soap_init(&soap);
    m = soap_bind(&soap, NULL, 8888, 100);
    if (m < 0) {
        soap_print_fault(&soap, stderr);
        exit(-1);
    }
    fprintf(stderr, "Socket connection successful\n");
    while (1) {
        s = soap_accept(&soap);
        if (s < 0) {
            soap_print_fault(&soap, stderr);
            exit(-1);
        }
        soap_serve(&soap);
        soap_end(&soap);
    }
 
    return 0;
} 
 
int ns1__sayHello(struct soap *soap, char* firstName, char* *greeting) {
    printf("ns1__sayHello(%s)\n", firstName);
 
    *greeting = (char*)soap_malloc(soap, 25);
    sprintf(*greeting, "Hello %s", firstName);
 
    return SOAP_OK;
}

#include "soapH.h"
#include "Hello_USCOREBinding.nsmap" 
 
int main(int argc, char **argv) {
    struct soap soap;
    char* greeting;
 
    soap_init(&soap);
 
    if (soap_call_ns1__sayHello(&soap, "http://localhost:8888", NULL, "world", &greeting) == SOAP_OK) {
        printf("%s\n", greeting);
    } else {
        soap_print_fault(&soap, stderr);
    }
 
    return 0;
}

A possible Makefile can be:

# C Compiler settings
CC=gcc
CC_FLAGS=-DLINUX -g -O2 -Wall

# Header files needed by the compiler
CC_INCLUDES=-I. -pthread

# Libraries needed by the linker 
LD_LIBS=-pthread    \
-L/usr/lib          \
-Wl,-rpath,/usr/lib \
-lgsoap

# Project Files
MODULES_SERVER=./Server.o \
./soapServer.o            \
./soapC.o

MODULES_CLIENT=./Client.o \
./soapClient.o            \
./soapC.o

all: server client

clean:
	rm -f server client $(MODULES_SERVER) $(MODULES_CLIENT)

server: $(MODULES_SERVER)
	$(CC) $(CC_INCLUDES) $(CC_FLAGS) -o $@ $(MODULES_SERVER) $(LD_LIBS)

client: $(MODULES_CLIENT)
	$(CC) $(CC_INCLUDES) $(CC_FLAGS) -o $@ $(MODULES_CLIENT) $(LD_LIBS)
	
%.o: %.c
	$(CC) $(CC_INCLUDES) $(CC_FLAGS) -c -o $*.o  $<