MOM including JMS is a great enabler for reliable communication between components, especially when you do that in a loosely coupled (asynchronous) manner. JMS provides the required APIs and provider-level SPIs for Java components to interact through MOM. Combining the power of messaging over a reliable channel along with the interoperability of web services provides us a greater flexibility with confidence in messaging characteristics. Web services over JMS are positioned in this space and it is nothing new since we have been doing that for many enterprise class transactions. The new thing here is the endless possibilities provided by the ESB architecture when combined with tested and proven EAI patterns. This is demonstrated in this chapter with samples. And keep reading—you are going to see more practical usages of the ESB architecture such as web service versioning in the coming chapters.