Chapter 14: Routing and Referral

Overview

As you saw when we looked at the various specifications in Chapter 12, WS-Routing and WS-Referral allow you to control the path that your message takes to its ultimate destination.

You can route messages in three ways using the facilities provided by WS-Routing and WS-Referral. We’ll look at each of these methods in turn.

We’ll start by looking at server-controlled routing, in which the route the message takes is determined by the details specified in a referral cache at the server. The client that makes a request to a Web service is unaware that the request has been forwarded to another destination to be processed.

The second form of routing that we’ll look at is a slight modification of server-controlled routing, in which the destination of the request is determined based on some other factor—the request might be forwarded to a different location depending on the time or day or the actual contents of the request. As with server-controlled routing, the client has no knowledge of the request being handled by a different destination than was requested.

The final form of routing we’ll look at is client-controlled routing, in which the client specifies the route that it wants the message to take. Each step along the way gets a chance to interact with the message, and possibly alter the route of the message, before passing it on to the next step.

Before we look at any of these types of routing, however, you need to understand how Web Services Enhancements (WSE) deals with routing under the covers.