Release 10.1A: OpenEdge Development:
Web Services

Elements of 4GL client access to Web services

Like most Web service client platforms, the 4GL relies on a WSDL file to define the interface for a Web service that it accesses. OpenEdge provides a utility, the WSDL Analyzer, that reads the WSDL file for a Web service and generates documentation describing requirements for invoking and managing Web service operations in the 4GL. OpenEdge also requires access to the WSDL file at run time to interpret 4GL calls to Web service operations and to manage the exchange of data between the 4GL client and the Web service.

Access to Web services and AppServers—similarities and differences

The 4GL views a Web service very much like an application service provided directly through the AppServer. To access a Web service, OpenEdge provides many of the same 4GL elements that you use to access a session-free AppServer, and it provides additional elements specifically designed to manage calls to a Web service that are not required to access an AppServer directly.

Requirements for accessing Web services in the 4GL

In general, all 4GL network deployment models support inherent access to Web services, including:

A small or large networked client application.
A WebClient application.
Business logic running on an AppServer.
SpeedScript running on a WebSpeed Transaction Server.

All you need is the WSDL file, any additional documentation provided for using the Web service, and a networked 4GL session and development environment to develop and deploy 4GL applications that access Web services.

For an overview of the tools and procedures for accessing industry Web services in the 4GL, see the "Programming 4GL clients to access industry Web services" section.

4GL applications accessing Progress 4GL Web services

It is possible for a 4GL application to access Progress 4GL Web services. However, the greater efficiency achieved by accessing an AppServer directly over the Internet using the AppServer Internet Adapter (AIA), and certainly the ability to access an AppServer directly within an intranet, makes the choice to use a Progress 4GL Web service interface for the same purpose somewhat less useful.

However, if you happen to use a Web service written in the Progress 4GL, you can follow the same procedures required of any Web service client to access a Progress 4GL Web service. For more information, see Part II, "Clients Accessing Progress 4GL Web Services."