Synchronous input processing with asynchronous result

Synchronous processing, in which the input is processed as soon as it arrives, may be combined with asynchronous results: if a response is needed, the response message is placed in a queue table and sent when the system is available.

This pattern must be considered when input processing does not take much time but creating and sending an output message is relatively costly. It is also useful if the responding service must guarantee the delivery of output messages: if an output message cannot be delivered because of an error, the system must retry after a period of time.

The advantage is that you are still using the easiest way to process input. Because output processing is asynchronous, it may be dealt with by a parallel process if needed.