Enterprise Integration Patterns: Designing, Building, and Deploying Messaging Solutions (Addison-Wesley Signature Series (Fowler))

by Hohpe Gregor

One excellent architectural style that uses a combination of Message Brokers is a Message Broker hierarchy (see figure). This configuration resembles a network configuration composed out of individual subnets. If a message has to travel only between two applications inside a subnet, the local Message Broker can manage the routing of the message. If the message is destined for another subnet, the local Message Broker can pass the message to the central Message Broker, which then determines the ultimate destination. The central Message Broker performs the same functions as a local Message Broker, but instead of decoupling individual applications, it decouples whole subsystems consisting of multiple applications.