Microsoft® SQL Server 2012 Unleashed

Planning Conversations Between Services

A conversation is a dialog between two services. The purpose of this dialog is, of course, the sending and receiving of messages, which ultimately leads to the completion of a task.

A powerful feature of Service Broker messaging is that it guarantees exactly-once-in-order (EOIO) messaging. This means that messages are sent exactly once; there’s no chance that a message can be sent twice because of a system issue, so the receiver doesn’t have to check whether a message has already been processed. It also means that messages are always ordered in their queue in the same order in which they were sent. (The queuing_order column of the queue indicates this order.) Service Broker makes sure of this, even in cases ...