In previous chapters we have covered the majority of the JBoss ESB core functionality, including services, out-of-the-box actions, gateways, and its registry. We are now going to cover another important aspect of an ESB, the ability to expose an ESB service as a web service and to consume an existing web service from within an ESB service.
A web service provides a standard mechanism through which one service can invoke a second, possibly remote, service without having to be concerned with any of the service implementation details, such as language and/or platform. The message exchange format is well defined as are the interactions which are allowed to occur between the client and server.
Web services enable many of the desirable attributes of an ESB service, such as loose coupling, and are likely to be present in many of the legacy services already existing within an organization.
In this chapter we will show how to:
- Export an ESB service as a web service
- Invoke an external web service
- Invoke a co-located web service
- Proxy a web service through the ESB, enabling interception and modification of the service invocation
So let's get on with it...
The examples in this chapter are based on a standard ESB application template that can be found under the Chapter8 directory within the sample download. We will modify this template application as we proceed through this chapter.
Before we start, please make sure that you have set up JBoss Developer Studio and JBoss 5.1 Runtime as described in Chapter 2.