The Advanced Message Queuing Protocol (AMQP) is an open standard application layer protocol for Message Oriented Middleware. The defining features of AMQP are message orientation, queuing, routing (including point-to-point and publish-and-subscribe), reliability and security (O'Hara).
AMQP mandates the behaviour of the messaging provider and client to the extent that implementations from different vendors are truly interoperable, in the same way as SMTP, HTTP, FTP, etc. have created interoperable systems. Previous attempts to standardise middleware have happened at the API level (e.g. JMS) and this did not create interoperability (Vinoski).
Reference:
http://en.wikipedia.org/wiki/AMQP
