Synchronous and Asynchronous Consumers

A message consumer can support either synchronous or asynchronous consumption of messages.

• Synchronous consumption means the consumer explicitly requests a message that has been delivered to the client runtime and then consumes it.

  Depending on the method used to request messages, a synchronous consumer can choose to wait (indefinitely) until a message is delivered to the client runtime, to wait a specified amount of time for a message, or to return immediately if there is no message available to be consumed (messages that were successfully produced but which the broker has not finished processing).

• Asynchronous consumption means that the message is automatically handed off to a message listener object (MessageListener) that has been registered with the consumer. The client consumes the message when a session thread invokes the onMessage() method of the message listener object.