As a JMS provider, Message Queue offers a messaging service that implements the JMS interfaces and that provides administrative services and control. So far, in illustrating JMS providers, the focus has been mainly on the role of the broker in relaying messages. But in fact, a JMS provider must include many elements in addition to the broker to provide reliable, secure, scalable messaging. Figure 1–6 shows the elements that make up the Message Queue message service. These include a variety of connection services (supporting different protocols), administrative tools, and data stores for messaging, monitoring, and user information. The Message Queue service itself includes all elements marked in gray in the figure.
As you can see, a full-featured JMS provider is more complex than the basic JMS model would lead one to suspect. The following sections describe the elements of the Message Queue service shown above. These elements can be divided into three categories: the broker, client runtime support, and administration.