MQTT is a publish/subscribe-based "lightweight" message protocol designed for communication between constrained devices, for example, devices with limited network bandwidth or unreliable networks. See http://mqtt.org/ for detailed information.

Apama provides a connectivity plug-in, the MQTT transport, which can be used to communicate between the correlator and an MQTT broker, where the MQTT broker uses topics to filter the messages. MQTT messages can be transformed to and from Apama events by listening for and sending events to channels such as prefix:topic (where the prefix is configurable).

The MQTT transport automatically reconnects in case of a connection failure. The transport will retry sending any messages sent after the connection has been lost when reconnection has succeeded

You configure the MQTT connectivity plug-in by editing the files that come with the MQTT bundle. The properties file defines the substitution variables that are used in the YAML configuration file which also comes with the bundle. See Adding the MQTT connectivity plug-in to a project for further information.

This transport provides a dynamic chain manager which creates chains automatically when EPL subscribes or sends to a correlator channel with the configured prefix, typically mqtt:. For the MQTT transport, there must be exactly one chain definition provided in the dynamicChains section of the YAML configuration file.

For more information on YAML configuration files, see Using Connectivity Plug-ins and especially Configuration file for connectivity plug-ins.