Publisher-Subscriber Patterns

Collaboration diagram for Publisher-Subscriber Patterns:

Modules
	Publisher-Subscriber
	The publisher-subscriber pattern is the simplest communication mechanism. It is included for pedagogical purposes only. Here, multiple consumers receive messages from one producer.
	Extended Publisher-Subscriber
	A fully asynchronous publish-subscribe mechanism whereby a forwarder (proxy) relays messages from multiple publishers to multiple subscribers.

Detailed Description

This pattern can be thought of as listening to the radio. The radio (publisher) will broadcast its content. The listener (subscriber) will then tune-in to hear the content. This conceptually simple pattern provides excellent one-to-many scalability. However, the subscriber will miss all content if it is not connected to the data feed. One caveat is that communication is a one-way street in that the publisher broadcasts and the subscriber listens. If your use-case requires the subscriber send information to the publisher then this messaging pattern will not work.