Examples of message flows

The asynchronous message model can be employed in several types of message flow, some of which cannot be easily supported with the conversational or RPC communications models.

Type of flow	Discussion	Communications model
Send-and-pray	A one way flow in which nothing need be or nothing can be known what happens to the message. E.g., airport display.	MQI
Send-and-nay	Exception only response. A two-way sequence in the event that there is something wrong with the message. The receiving agent notifies the sending agent. E.g., batch remittance.	MQI
Send-and-say	Question-and-answer sequence in which a response is mandatory. E.g., change of address.	MQI
Send-and-receive	Similar to send-and-say, but may not involve question-and-answer sequences. E.g., account balance.	CPI-C RPC MQI
Send-and-receive-and-...	Extension of send-and-receive with an extended sequence of exchanges. E.g., compiled report.	CPI-C MQI
Send-send-...-receive	Closed information flow. The information request may be sent through a network of many systems before the answer is received directly by the sender. E.g., checking account balance.	MQI
Send-send-...-and-receive-receive-...	Closed lattice information flow. Messages are distributed to several programs for processing. There may be collector nodes to gather responses that are not returned directly to the sender. E.g., credit application approval.	MQI

This table is adapted from Blakely, Burnie, Harry Harris and Rhys Lewis. Messaging and Queuing Using the MQI. McGraw-Hill, 1995.

Last updated 29 Feb 2008