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 mqtt:topic (where mqtt: is the default prefix).

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.

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

The samples/connectivity_plugin/application/mqtt directory of your Apama installation includes a sample which demonstrates how to use the MQTT connectivity plug-in to send and receive JSON messages to and from an MQTT broker. See the README.txt file included with this sample for complete instructions for how to run the sample application.