The Advanced Message Queuing Protocol (AMQP) is an open standard application layer protocol for Message Oriented Middleware. AMQP is often used with a Broker that relays messages between applications that cannot communicate directly.

Publishers send AMQP messages to AMQP endpoints. Subscribers listen to AMQP endpoints for incoming messages. If a Broker is involved it may persist messages so they can be delivered even if the subscriber is not online. Brokers may also allow messages to be sent to multiple Subscribers.

The AMQP protocol defines a binary encoding for all messages with a header and a body. The header allows applications to insert additional information as name-value pairs that are serialized using the AMQP binary encoding. The body is an opaque binary blob that can contain any data serialized using an encoding chosen by the application.

This document defines two possible message mappings for the AMQP message body: the UADP message mapping defined in 7.2.3 and a JSON message mapping defined in AMQP Brokers have an upper limit on message size. The limit is defined by the AMQP field max-message-size. The mechanism for handling NetworkMessages that exceed the Broker limits depends on the MessageMapping. For MessageMappings that support chunking, the NetworkMessage shall be broken into multiple chunks. The chunk size plus the AMQP header should not exceed the AMQP max-message-size. For MessageMappings that do not support chunking, the NetworkMessages exceeding the maximum size mut be skipped. Diagnostic information for such error scenarios are provided through the Events of the type PubSubTransportLimitsExceedEventType defined in and through the FailedTransmissions counter of the PubSubDiagnosticsWriterGroupType defined in

Security with AMQP is primary provided by a TLS connection between the Publisher or Subscriber and the AMQP Broker, however, this requires that the AMQP Broker be trusted. For that reason, it may be necessary to provide end-to-end security. Applications that require end-to-end security with AMQP need to use the UADP NetworkMessages and binary message encoding defined in JSON encoded message bodies rely on the security mechanisms provided by AMQP and the AMQP Broker.