Real time ordered delivery can be achieved if you can control the sending of messages. A regular orchestration with a single activation will not do the trick as messages in the MessageBox
will be picked up by the XLANG engine, which will spin up as many instances of orchestration as there are messages. Messages can be different in size, and different amounts of time will, therefore, likely be required to process them through BizTalk. Therefore, the message order can easily change during the processing of messages. To be able to do it in a First In First Out (FIFO) manner, the first message needs to be completed before the next message is picked up to be processed. You will basically need one instance of an orchestration to complete all processing of messages. Implementing a FIFO pattern requires you to build a sequential convoy using message correlation and ordered delivery flags in BizTalk.
Convoys are a well known concept in the BizTalk world. Convoys are used...