Release 10.1A: OpenEdge Development:
Web Services

Creating client interfaces from WSDL

You have two basic options for handling Web service SOAP messages from your client application:

Write your own code to send and receive the SOAP messages as specified in the WSDL.
Generate client interfaces directly from the WSDL using a Web service client toolkit. Some of the client toolkits available today include:
Microsoft .NET
Apache Axis
Iona XMLBus
Progress 4GL

Most of this chapter assumes you are using a similar client toolkit to generate client interfaces. These proxies provide an API that generally appears as an interface to application functions, but that actually provides an interface to messaging operations that hide the complexity of exchanging SOAP messages over HTTP. (For information on SOAP over HTTP, see the "Handling communications with Web services" section.)

Each client toolkit generates these proxies in a unique manner, but most create objects with methods. Usually, they create one object for each <portType> and one object for each <complexType> specified in the WSDL.

These toolkits might generate methods to handle SOAP messages in any of the following ways for each Web service operation:

Handling the request and response messages in a single method.
Note: All examples in this chapter follow this technique.
Providing separate methods to handle the request and response messages.
Providing a request method with the response message as an output parameter or return value.

Whatever differences exist in how client platforms generate and interpret SOAP messages, the Web services tools generate WSDL that allows all clients to generate and interpret all SOAP messages required to access Web-services-tools-defined Web services.