Message queueing in middleware by a message broker

A message broker configured to handle messages received from a plurality of client applications comprises a plurality of message queues that are each associated with a different task. A first synchronous message is received at a first message queue from a first client application. A determination is made that at a time the first synchronous message is received there is an earlier-received message from a different client application waiting in the first message queue. In response to the determination, the first synchronous message is coalesced with the earlier-received message such that a task associated with the first message queue is executed only once for both messages and a notice of the execution is returned to the first client application.