We intend to standardise the Elvin protocol through the IETF . Consumers subscribe to subjects and receive all the messages in that virtual channel. Elvin subscriptions, on the other hand, describe the contents of the messages the consumer is interested in. This means less traffic for the consumer, since it doesn't have to listen to the whole channel. It also makes it simple to restructure your applications, and to use applications developed by other organisations.
Subscribers can then match against that string.
This asynchronous style of communication is superfically similar to notification. Unlike notification however, message queues are named, and the sending application must explicitly direct messages to a queue which it knows that receiver is going to check. Notification uses a different mechanism, relying on the service to decide where to send notifications. Producer applications do not need to know what happens to their notifications once they are sent. Message queueing and notification are two different styles of communication, and while initially they can seem similar, a closer analysis will determine which one you need.