Creating and Consuming Web Services in Visual Basic®

Server to Server Asynchronous Communications

Sometimes the time between request and response will be really long. The processing may take a long time, a person may need to do some work before returning a result, or it just might not make sense to wait until the call completes. For example, when placing a purchase order, the client may only care that the order was received. Later, the server can notify the client of the following events:

• Payment processed

• Order being processed

• Order shipped

• Changes in order location up through delivery

These changes may happen over several days, making it difficult to keep any connections alive. Instead of keeping a connection alive, why not send the request and response over independent connections? To do this, ...