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RabbitMQ is an open-source message-broker software (sometimes called message-oriented middleware) that originally implemented the Advanced Message Queuing Protocol (AMQP) and has since been extended with a plug-in architecture to support Streaming Text Oriented Messaging Protocol (STOMP), MQ Telemetry Transport (MQTT), and other protocols.
A retained message is a normal MQTT message with the retained flag set to true. The broker stores the last retained message and the corresponding quality of service (QoS) for the selected topic. Each client that subscribes to a topic pattern that matches the topic of the retained message receives the retained message immediately after they ...
MQTT is an ISO standard (ISO/IEC PRF 20922) [1] publish–subscribe-based messaging protocol.It works on top of the Internet protocol suite TCP/IP. It is designed for connections with remote locations where a "small code footprint" is required or the network bandwidth is limited.
The HTTP persistent connections do not use separate keepalive messages, they just allow multiple requests to use a single connection. However, the default connection timeout of Apache httpd 1.3 and 2.0 is as little as 15 seconds [ 6 ] [ 7 ] and just 5 seconds for Apache httpd 2.2 and above.
The windowing system places messages indicating user or other events, such as timer ticks or messages sent by other threads, into the message queue. The GUI application removes these events one at a time by calling a routine called getNextEvent() or similar in an event loop , and then calling the appropriate application routine to process that ...
The primary disadvantage of many message-oriented middleware systems is that they require an extra component in the architecture, the message transfer agent (message broker). As with any system , adding another component can lead to reductions in performance and reliability, and can also make the system as a whole more difficult and expensive ...
As a message is placed on a queue or a configuration change is made, the data is also logged. In the event of a failure, the log is used to recreate damaged objects and recreate messages. Only persistent messages are recreated when a failure occurs—"non-persistent" messages are lost. Non-persistent messages can be sent across a channel set to ...
The process of selecting messages for reception and processing is called filtering. There are two common forms of filtering: topic-based and content-based. In a topic-based system, messages are published to "topics" or named logical channels. Subscribers in a topic-based system will receive all messages published to the topics to which they ...