JmsTemplate synchronous receive

Question

How the jmstemplate receive() method is synchronized? Sender send message to a broker and on the other side consumer consumes message from broker queue or a topic. For receive, it will be some polling thread waiting for some data on a broker. How the synchronization then gets maintained?

Answer 1

JmsTemplate uses the JMS API behind the scene and in particular the MessageConsumer. That service can either attempt to receive a Message without waiting (receiveNoWait) or it can wait a configurable amount of time (receive(long timeout)). When it's being invoked with a timeout of 0, the receive method blocks until a message arrives. There's nothing in JmsTemplate that deals with all this (i.e. it is provided by the client broker implementation).

A more regular way of receiving messages is to use a listener container. With Spring, the DefaultMessageListenerContainer allows you to use a thread poll to process incoming messages. Check the jms documentation of the Spring framework for more information.