MessageBroker ==Message router==Mediator

The notion of a Message Router is central to the concept of a Message Broker, implemented in virtually all commercial EAI tools. These tools accept incoming messages, validate them, transform them, and route them to the correct destination. This architecture alleviates the participating applications from having to be aware of other applications altogether because the Message Broker brokers between the applications. This is a key function in enterprise integration because most applications to be connected are packaged or legacy applications and the integration has to happen nonintrusively—that is, without changing the application code. Therefore, the middleware has to incorporate all routing logic so the applications do not have to. The Message Broker is the integration equivalent of a Mediator presented in [GoF].