message queuing telemetry transport (MQTT)
Message Queuing Telemetry Transport (MQTT) is an extremely simple publish-subscribe method for exchanging messages between devices and components, for example smart sensors. The MQTT protocol was developed specifically for devices with limited functionality and for unreliable networks with small bandwidth and high latency. It is used in low power wide area networks( LPWAN), among other applications.
The MQTT protocol is suitable for transmitting small amounts of data over poor links. It minimizes network bandwidth and places low requirements on devices, while at the same time data transmission achieves high reliability. These requirements exist predominantly in sensor networks, machine to machine( M2M), telemedicine, patient monitoring, and the Internet of Things( IoT). In these applications, connected devices are Always On and constantly communicating with each other.
The open, license-free MQTT protocol was developed by IBM back in 1999 for satellite communications and later used in many industrial applications. It is an application protocol that is based on the TCP protocol and also supports the IP prot ocols IPv4 and IPv6. The MQTT protocol can be transmitted in encrypted form using the TLS protocol, Transport Layer Security (TLS). It is extremely easy to implement, knows three different quality of service( QoS) for service options, and can run uninterrupted sessions with fixed and mobile devices.
OASIS has been working on its standardization since 2013. The MQTT protocol is also known as theSCADA protocol and as WebSphere MQTT (WMQTT). The Internet Assigned Numbers Authority( IANA) has reserved ports 1883 and 8883 for MQTT. To ensure messagesecurity, users can transmit their name and password in an MQTT packet. In addition, messages can be encrypted using Secure Socket Layer( SSL).
The MQTT protocol works in the event-driven publish-subscribe method with a central server that forms the MQTT broker and through which the data sources, called publishers, and the data users, called subscribers, are connected. Publishers can be sensors that report their readings to the broker, subscribers can be laptops, tablets or smartphones that subscribe to the broker services and have the subscribed information delivered by the broker.
MQTT does not have a fixed data format. The data can be transmitted as raw data, in JSON or XML.