We defined messages and we discussed how message endpoints act on the messages, so where does a message channel fit in? A message channel is an implementation of the EAI design pattern that decouples the endpoint. Endpoints do not need to be aware of each other's type; they register with channels and it's the responsibility of the channel to deliver the messages safely between endpoints. Each channel has a logical identity—it may be a unique name or ID through which it can be referred and registered to. Depending on how channels handle the messages, they can be classified in two broad categories:
Point-to-point channel
Publish-subscribe channel