Chapter 1. Introduction

For many applications, using a single message broker is sufficient. However, there are many cases where using multiple interconnected brokers is more appropriate. For example, if you need to ensure that your application is continuously available, if your application needs to process large volumes of messages, or if your integration solution calls for message processing across distributed location a network of brokers will work better than a single message broker.

Red Hat JBoss A-MQ facilitates these use cases by making it possible to build up a network of brokers. A network of brokers is a set of two or more brokers connected together by network connectors. All of the brokers in the network share information about the clients and destinations each broker hosts. The connected brokers use this information to route messages through the network.

A network of brokers is created when one broker establishes a network connector to another broker. Once the network connector is established the broker that established the connection discovers information about the destinations being hosted on the other broker and which consumers are actively listening for messages on the destinations. Using this information, the first broker can route messages from its producers to consumers on the connected broker. A simple network of brokers, such as this, spreads load between the two brokers, allows each broker to be configured for specific needs, and partitions the producers and consumers.

A network of brokers can be expanded by introducing more brokers to the network. This allows you to build up sophisticated network topologies. You can also create bidirectional connections between brokers to allow for more sophisticated message routing.

To create a robust network, it is important to be able to deploy brokers dynamically through out your infrastructure. It is also important to be able to add and remove brokers as needed. JBoss A-MQ facilitates this with a number of discovery protocols. These protocols allow brokers and clients to determine a list of active brokers. Brokers can automatically add new brokers to a network of brokers and removes inactive brokers. Clients always have a list of brokers that are available if they need to failover to a new broker.