Creating and Consuming Web Services in Visual Basic®

Design Pattern for Asynchronous Method Calls

The .NET Framework defines a design pattern for calling methods asynchronously. It is important to use a common design pattern to avoid confusion among developers. This pattern dictates that there are two asynchronous methods for every synchronous method. Specifically, for every synchronous method there is a Begin and an End asynchronous method. The Begin method is called by a client to initiate the execution of the method. With this call, the client tells the method to begin processing the method and control is returned immediately to the client. There are a few options for determining if the call has been completed. These include specifying a callback method that will be called when the execution ...