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Application Migration and Development Guide
Application Development with PAS for OpenEdge : PAS for OpenEdge and Client Interaction : Understanding synchronous and asynchronous requests : Process control flow
Process control flow
The following figure compares the process flow within an application using synchronous and asynchronous requests.
Figure 1. Synchronous and asynchronous requests
In this figure, one client (Client 1) makes synchronous requests and another client (Client 2) makes asynchronous requests to two PAS for OpenEdge sessions (Session 1 and Session 2). For Client 1, control flows in sequence between client and PAS for OpenEdge instance. For Client 2, control flows in parallel between client and PAS for OpenEdge instance. Assuming that the clients and PAS for OpenEdge instance perform the same work, Client 2 can conceivably complete the work in less time than can Client 1. The advantage for Client 2 comes with the parallelism that asynchronous requests can achieve. In this case, the actual advantage that Client 2 affords depends on its ability to respond to the results from the server sessions at the moment they arrive, while doing its own share of the work until the results actually do arrive.