The unification of JMS messaging models, introduced in the JMS 1.1 specification, provides generic connection, session, message, message producer, and message consumer interfaces. The advantage is that you can have queue-based messages and topic-based messages in a single transaction.

You can declare messaging model specific methods at any point, but you are then bound to that messaging model. For example, you can use a generic ConnectionFactory to create a QueueConnection. Then, you would have to create a QueueSession, QueueSender, and QueueReceiver.

Eventually you have to declare what set of behaviors to apply to a message. This occurs when you specify the destination. A destination is either a topic or a queue. You can send to a statically defined queue or publish to a dynamically defined topic, both with the same name. The broker considers these different types of destinations—one is a queue and one is topic. They have different authorization rules and require different handling. The next two sections describe and differentiate between each of the messaging models.