MQTT Interface

MQTT is a publish-subscribe protocol to transport arbitrary data between clients. MQTT clients connect to a server (called MQTT broker) and publish and/or subscribe to topics, identified by an (almost) arbitrary name. Topics are often structured in a hierarchy using slashes, for example neobotix/platform/mpo-700-1/navigation/map_pose.

PlatformPilot can be set up to act as an MQTT client to an MQTT broker, translating messages from and to internal topics. All sent messages will be JSON objects, except possibly the Last-Will message. All messages that should be received also have to be JSON objects.

Client

In your configuration folder add or append a file named mqtt_proxy_list to contain a list of the MQTT proxies that should be started. Each one will be one MQTT client (usually you only need one per broker).

["MQTT_Proxy_1", "MQTT_Proxy_2", ...]

The individual options can be set in the corresponding configuration file, e.g. in MQTT_Proxy_1.json. The only necessary setting is the broker address, but you probably also want to specify the client ID and the exported topics. Here is an example configuration:

{
        "address": "tcp://10.1.30.42:1883",
        "client_id": "nbx-pp-1",
        "export_map": [
                ["platform.system_state", "neobotix/<robot-name>/platform/system_state"],
                ["platform.emergency_state", "neobotix/<robot-name>/platform/emergency_state"]
        ],
        "export_map_ex": [
                ["platform.info", {
                        "topic": "neobotix/<robot-name>/platform/info",
                        "retained": true
                }]
        ],
        "last_will": {
                "topic": "neobotix/<robot-name>/disconnect",
                "message": "Apparently, an unexpected disconnect happened..."
        }
}

Find all configuration options at vnx.mqtt.Proxy.