SOAP current time client & server example

Overview

This example implements a simple SOAP/XML API client and server in C++ to obtain the current time. The Web service specified is a tiny one-liner. The client and server programs are tiny too.

A more interesting one-liner example service is our gSOAP Docker container example that does not require a Web server installed as it runs an image of a stand-alone service within a container.

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Web services specification example

The XML Web service is specified in the gmt.h file for the gSOAP soapcpp2 tool to process. This gmt.h specification defines one operation in just one line of code to return the current time in GMT:

t__gmt(time_t*);

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Implementing the client application

The client application gmtclient.cpp is run at the command line and prints the current time:

#include "soapH.h"
#include "gmt.nsmap"
int main()
{
  time_t t;
  struct soap *soap = soap_new();
  soap_call_t__gmt(soap, "http://localhost:8080", "", &t);
  printf("The current time is %s\n", ctime(&t));
  soap_destroy(soap);
  soap_end(soap);
  soap_free(soap);
  return 0;
}

See the tutorials on how to use HTTP proxies and HTTPS.

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Build steps for the client application

Generate the service and data binding interface for the client side with:

where option -r generates a report, and option -CL generates the client side only without (the unused) lib files.

This generates several files, including:

• soapStub.h a copy of the specification in plain C/C++ header file syntax without annotations.
• soapH.h declares XML serializers.
• soapC.cpp implements XML serializers.
• soapClient.cpp implements the client-side XML services API.
• gmt.nsmap XML namespace binding table to #include
• soapReadme.md service and data binding interface details.

To build the example client application we also need stdsoap2.h and stdsoap2.cpp:

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Implementing a CGI server application

The CGI server application gmtserver.cpp implements the service operations and accepts requests on stdin using soap_serve(soap):

#include "soapH.h"
#include "gmt.nsmap"
int main()
{
  return soap_serve(soap_new());
}
int t__gmt(struct soap *soap, time_t *t)
{
  *t = time(0);
  return SOAP_OK;
}

Install the CGI application in the cgi-bin folder of your Web server.

To implement stand-alone services running as a Web server without requiring a third-party Web server such as Apache, see the calc++ example for an example. See also our tutorials for details on deploying services with Apache or IIS and how to increase the robustness of services.

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Implementing a stand-alone server application

The stand-alone local server application gmtserver_local.cpp implements the service operations and accepts requests on port 8080.

#include "soapH.h"
#include "gmt.nsmap"
int main()
{
  struct soap *soap = soap_new();
  SOAP_SOCKET m = soap_bind(soap, NULL, 8080, 1);
  if (soap_valid_socket(m) == SOAP_OK
  {
    fprintf(stderr, "Socket connection successful: master socket = %d\n", m);
    while (true)
    {
      SOAP_SOCKET s = soap_accept(soap);
      fprintf(stderr, "Socket connection successful: socket = %d\n", s);
      if (soap_valid_socket(s) != SOAP_OK)
        break;
      soap_serve(soap);
      soap_destroy(soap);
      soap_end(soap);
    }
  }
  soap_print_fault(soap, stderr);
  soap_free(soap);
  exit(1);
}
int t__gmt(struct soap *soap, time_t *t)
{
  *t = time(0);
  return SOAP_OK;
}

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Build steps for the server application

Generate the service and data binding interface for the server side with:

where option -r generates a report, and option -SL generates the server side only without (the unused) lib files.

This generates several files, including:

• soapStub.h a copy of the specification in plain C/C++ header file syntax without annotations.
• soapH.h declares XML serializers.
• soapC.cpp implements XML serializers.
• soapServer.cpp implements the server-side XML services API.
• gmt.nsmap XML namespace binding table to #include
• soapReadme.md service and data binding interface details.

To build the example server application we also need stdsoap2.h and stdsoap2.cpp:

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Running the example

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Readme report

See the auto-generated soapReadme for this example.

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