AMQP, which stands for Advanced Message Queuing Protocol, was designed as an open replacement for existing proprietary messaging middleware. Two of the most important reasons to use AMQP are reliability and interoperability. As the name implies, it provides a wide range of features related to messaging, including reliable queuing, topic-based publish-and-subscribe messaging, flexible routing, transactions, and security. AMQP exchanges route messages directly—in fanout form, by topic, and also based on headers.