Chapter 10. JMS-to-JMS Bridge

The purpose of a JMS-to-JMS bridge is to enable two different JMS providers that speak a different wire protocol to communicate with each other. A bridge consists essentially of two different client libraries strapped together: one client library facilitates communication with the first JMS provider; and the other client library facilitates communication with the second JMS provider.

The basic architecture is illustrated in Figure 10.1, “Architecture of the JMS-to-JMS Bridge”.

JMS defines the interfaces for a messaging service and describes how a client interacts with the messaging service. But JMS does not define the details of a messaging implementation and, in particular, JMS does not specify how to implement an on-the-wire protocol for transmitting messages. Because of this, different JMS providers use different wire protocols.

For Java clients, the ActiveMQ broker normally uses the Openwire/TCP protocol, which is not compatible with a third-party JMS provider. Hence, you cannot simply connect an ActiveMQ broker directly to a third-party JMS provider. It is generally necessary to interpose a JMS-to-JMS bridge between the ActiveMQ broker and the third-party JMS provider.

To enable the JMS-to-JMS bridge to talk to the ActiveMQ broker, it is necessary for the ActiveMQ client libraries to be installed in the bridge. These ActiveMQ client libraries are normally installed by default in JBoss A-MQ, so no action is required to make them available.

To enable the JMS-to-JMS bridge to talk to the third-party JMS provider, it is necessary for the third-party client libraries to be installed in the bridge. These third-party client libraries are not available by default in the JBoss A-MQ container. Third-party JMS providers are licensed separately from JBoss A-MQ. After purchasing the relevant licence from a third-party vendor, you can install the relevant client libraries into the JBoss A-MQ container (see Section 10.3.7, “Sample Bridge Configuration”).

The JMS API is layered between the JMS-to-JMS bridge and the client libraries. The JMS API enables the bridge to invoke both of the client libraries (ActiveMQ and third-party) using standard method calls.

There are two different approaches to defining router rules, depending on which bridge implementation you choose: