One of the biggest benefits of using the ESB technology is the benefits of the publish/subscribe message pattern; refer to http://en.wikipedia.org/wiki/Publish-subscribe_pattern.

The publish/subscribe pattern has a publisher that sends messages to a queue, say a MSMQ MyPublisher queue. Subscribers, say Subscriber1 and Subscriber2, will listen for messages on the queue that the subscribers are defined to take from the queue. If MyPublisher cannot process the messages, it will return them to the queue or to an error queue, based on the reasons why it could not process the message. The queue that the subscribers are looking for on the queue are called endpoint mappings. The publisher endpoint mapping is usually based on the default of the project's name. This concept is the cornerstone to understand NSB and ESBs. No messages will be removed, unless they are explicitly told to be removed by...