Release 10.1A: OpenEdge Application Server:
Developing AppServer Applications

Understanding synchronous and asynchronous requests

The Progress 4GL client and AppServer support two types of remote procedure execution for both session-managed and session-free applications:

Synchronous request — (Default) Where the client blocks and waits for the result of the remote request before continuing execution.
Asynchronous request — Where the client continues execution after initiating the request and processes the result whenever the AppServer makes it available.

The 4GL client also supports asynchronous requests to industry Web services, which work much like session-free asynchronous requests to an AppServer. For more information on 4GL asynchronous requests to a Web service, see OpenEdge Development: Web Services .

Note: OpenEdge does not provide built-in support for asynchronous requests in Open Clients or for Progress 4GL Web services. You can implement your own asynchronous request mechanism in Java Open Clients using threads (see OpenEdge Development: Java Open Clients ).