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

by Hohpe Gregor

Message Channels (60) provide a very basic form of routing capabilities. An application publishes a Message (66) to a Message Channel (60) and has no further knowledge of that Message’s (66) destination. Therefore, the path of the Message (66) can change depending on which component subscribes to the Message Channel (60). However, this type of “routing” does not take into account the properties of individual messages. Once a component subscribes to a Message Channel (60), it will by default consume all messages from that channel regardless of the individual message’s specific properties. This behavior is similar to the use of the pipe symbol in UNIX to process text files. It allows you to compose processes into a Pipes and Filters (70) chain, but for the lifetime of the chain, all lines of text undergo the same steps.