16.2. Servlets

The WS-Coordination, WS-Atomic Transaction, and WS-Business Activity protocols are based on one-way interactions of entities rather than traditional synchronous request/response RPC-style interactions. One group of entities, called transaction participants, invoke operations on other entities, such as the transaction coordinator, in order to return responses to requests. The programming model is based on peer-to-peer relationships, with the result that all services, whether they are participants, coordinators or clients, must have an active component that allows them to receive unsolicited messages.

In XTS, the active component is achieved through deployment of JaxWS endpoints. Each XTS endpoint that is reachable through SOAP/XML is published via JaxWS, without developer intervention. The only requirement is that transactional client applications and transactional web services must reside within a domain capable of hosting JaxWS endpoints, such as an application server. In the case of the Enterprise Application Platform, JBoss Application Server provides this functionality.