Release 10.1A: OpenEdge Development:
Web Services

Mapping Progress procedures to SOAP messages

The mapping of a Progress procedure (or, similarly, a user-defined function) to its final representation as a pair of SOAP request/response messages follows a well-defined series of steps:

ProxyGen generates a Web service definition that includes the selected Progress procedure during Web service development (see OpenEdge Development: Open Client Introduction and Programming ).
The WSA generates the WSDL file for the Web service during Web service deployment (see OpenEdge Application Server: Administration ). This WSDL file includes a series of elements that define a Web service operation that is mapped to the selected Progress procedure in the context of some Open Client object as specified in ProxyGen.
A client developer obtains the WSDL file and typically generates the source code for the client interface by running a client interface generator. This interface generator, which often comes as part of a Web services client development platform, reads the WSDL file and typically writes out the source code for the client interface as a series of objects and methods, each of which represents a Web service operation. One of these methods maps to the Web service operation defined in the WSDL file from Step 2.
Note: In OpenEdge, the WSDL Analyzer generates documentation on how to represent Web service operations in the 4GL. For more information, see Chapter 8, " Analyzing WSDL for Progress 4GL Access to Web Services."
The client developer writes the client application that uses the client interface generated in Step 3. The application invokes the method mapped to the Web service operation defined in Step 2, which sends a SOAP request message to the WSA where the Web service is deployed.
The WSA receives the SOAP request and packages the input parameters in an AppServer message which results in executing the corresponding Progress procedure on an AppServer.
The Progress procedure then returns any output parameters and any return value to the WSA.
The WSA packages these procedure results in a SOAP response message, which it returns to the client that originally sent the request.

In short, this process transforms:

4GL procedure prototype to WSDL operation (Web service development).
WSDL operation to client method prototype (client development).
Client method call to SOAP request/response message pair (run time).

The following examples show how these three transformations proceed.

Note: Some of these examples are available as samples on the Documentation and Samples CD or Progress Documentation Web site. For more information on accessing them, see Chapter 6, " Sample Progress 4GL Web Services and Client Applications."