A transactional Web service must ensure that a service invocation is included in the appropriate transaction. This usually only affects the operation of the participants and has no impact on the operation of the rest of the Web service. XTS simplifies this task and decouples it from the business logic, in much the same way as for transactional clients
. XTS provides a handler which detects and extracts the context details from the headers in incoming SOAP headers, and associates the web service thread with the transaction. The handler clears this association when dispatching SOAP responses, and writes the context into the outgoing message headers. This is shown in Figure 19.1, “Context Handlers Registered with the SOAP Server”
The service side handlers for JAX-WS come in two different versions. The normal handler resumes any transaction identified by an incoming context when the service is invoked, and suspends this transaction when the service call completes. The alternative handler is used to interpose a local coordinator. The first time an incoming parent context is seen, the local coordinator service creates a subordinate transaction, which is resumed before the web service is called. The handler ensures that this subordinate transaction is resumed each time the service is invoked with the same parent context. When the subordinate transaction completes, the association between the parent transaction and its subordinate is cleared.
188.8.131.52. JAX-WS Service Context Handlers
To register the JAX-WS server-side context handler with the deployed Web Services, you must install a handler chain on the Server Endpoint Implementation class. The endpoint implementation class annotation, which is the one annotated with a
javax.jws.WebService, must be supplemented with a
javax.jws.HandlerChain annotation which identifies a handler configuration file deployed with the application.
When registering a normal JAX-WS service context handler, you must instantiate the
com.arjuna.mw.wst11.service.JaxWSHeaderContextProcessor class. If you need coordinator interposition, employ the
Figure 19.1. Context Handlers Registered with the SOAP Server