Asynchronous requests allow an ABL client to execute a remote procedure and continue execution before a server session has completed (or even begun) executing the remote request. This mechanism enhances client performance, especially in an event-driven application where the user can continue interacting with the client application while the server processes the remote request.

In the following sections, when executing an asynchronous request, ABL places the request on a send queue for the connection until the server can execute the specified remote procedure. Similarly, when the procedure completes execution, ABL places the results on a response queue, where the results wait until the client handles the PROCEDURE-COMPLETE event associated with the request. As a result, all asynchronous requests on a session-managed connection are guaranteed to be executed, with results returned, in the order you submit them. For more information on the send and response queues, see PAS for OpenEdge and Client Interaction.