18.2.4. Application Messages

Application messages are the requests and responses sent between parties, that constitute the work of a business process. Any such messages are considered opaque by XTS, and there is no mandatory message format, protocol binding, or encoding style. This means that you are free to use any appropriate Web Services protocol. In XTS, the transaction context is propagated within the headers of SOAP messages.
XTS ships with support for service developers building WS-Transactions-aware services on the JBoss Enterprise Application Platform. Interceptors are provided for automatic context handling at both client and service, which significantly simplifies development, allowing you to concentrate on writing the business logic without being sidetracked by the transactional infrastructure. The interceptors add and remove context elements to application messages, without altering the semantics of the messages themselves. Any service which understands what to do with a WS-C context can use it. Services which are not aware of WS-C, WS-Atomic Transaction and WS-Business Activity can ignore the context. XTS manages contexts without user intervention. WS-C, WS-Atomic Transaction, and WS-Business Activity Messages

Although the application or service developer is rarely interested in the messages exchanged by the transactional infrastructure, it is useful to understand what kinds of exchanges occur so that the underlying model can be fitted in to an overall architecture.
WS-Coordination, WS-Atomic Transaction and WS-Business Activity-specific messages are transported using SOAP messaging over HTTP. The types of messages that are propagated include instructions to perform standard transaction operations like begin and prepare.


XTS messages do not interfere with messages from the application, an application need not use the same transport as the transaction-specific messages. For example, a client application might deliver its application-specific messages using SOAP RPC over SMTP, even though the XTS messages are delivered using a different mechanism.