1.3.1.3 Offline Message Exchange Scenario

In this scenario, salesperson C is visiting various customers and creating their purchase orders. However, the salesperson does not have access to the server and can upload these orders to the server only after he returns to his branch office. The order application uses some mechanism (for example, Microsoft Message Queuing) to store these messages locally, and the mechanism then relays the message to the server when the salesperson is again online.

This scenario differs from the scenario in section 1.3.1.2 because the receiving end of the protocol (that is, the relay) cannot actively participate in the protocol. This is a "store and forward" scenario in which the sending end of the protocol stores the message frame in an intermediate store, and later, the message frame is forwarded to, or retrieved by, the receiving end, which then extracts the message from the message frame.

Depending on the scenario characteristics, the message properties are sent on a per-message basis or sent once in advance of a number of messages. The latter case uses the same session semantic as before except that the session establishment involves participation from only one end.