WSO2 ESB comes with a built-in Qpid server (New in version 4.0). Apache Qpid™ is a cross-platform Enterprise Messaging system which implements the Advanced Message Queuing Protocol (AMQP). Enterprise Messaging systems let programs communicate by exchanging messages.
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Message Broker
A Message Broker (New in Version 4.0) is a built-in JMS provider/broker powered by Apache Qpid. The primary aim of the message broker is is to provide a persistence and broker functionality across Carbon. Once the task is completed, users of Carbon should have an embedded broker such as Apache ActiveMQ which they can consume across the Carbon.
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