Message exchange pattern
From AMWA
A Message Exchange Pattern (MEP) describes the pattern of messages required by a communications protocol to establish or use a communication channel. There are two major message exchange patterns: a request-response pattern, and a one-way pattern. A request-response pattern can be synchronous or asynchronous. In the latter case, the requester does not have to stop its activities until a response is received.
A more loosely coupled MEP is the publish/subscribe pattern. In this pattern, an events receiver expresses interest, usually via an events broker, in receiving event messages of a particular type. An events emitter broadcasts events to any events receivers which subscribed for that type of events. This is also usually accomplished via an events broker.
