Message Oriented Model
 
Important Definitions
-  Correlation is the association of a message with a context. Message correlation ensures that the agent requesting a service execution can match the reply with the request, especially when multiple replies may be possible. 
-  A message is the basic unit of data sent from one software agent to another in the context of Web services.
-  A message envelope is that meta-data associated with a message that permits the message to be delivered, intact.
-  A Message Exchanage Pattern (MEP) is a template, devoid of application semantics, that describes a generic pattern for the exchange of messages between agents.