mod_pubsub_mqtt

Introduction

MQTT is a lightweight binary pubsub protocol suited to embedded devices. This module provides a way for MQTT clients to connect to Prosody and publish or subscribe to local pubsub nodes.

The module currently implements MQTT version 3.1.1.

Details

MQTT has the concept of ‘topics’ (similar to XMPP’s pubsub ‘nodes’). mod_pubsub_mqtt maps pubsub nodes to MQTT topics of the form <HOST>/<TYPE>/<NODE>, e.g.pubsub.example.org/json/mynode.

The ‘TYPE’ parameter in the topic allows the client to choose the payload format it will send/receive. For the supported values of ‘TYPE’ see the ‘Payloads’ section below.

Limitations

The current implementation is quite basic, and in particular:

• Authentication is not supported
• Only QoS level 0 is supported

Payloads

XMPP payloads are always XML, but MQTT does not define a payload format. Therefore mod_pubsub_mqtt has some built-in data format translators.

Currently supported data types:

• json: See XEP-0335 for the format.
• utf8: Plain UTF-8 text (wrapped inside <data xmlns="https://prosody.im/protocol/mqtt"/>)
• atom_title: Returns the title of an Atom entry as UTF-8 data

Configuration

There is no special configuration for this module. Simply load it on your pubsub host like so:

Component "pubsub.example.org" "pubsub"
    modules_enabled = { "pubsub_mqtt" }

You may also configure which port(s) mod_pubsub_mqtt listens on using Prosody’s standard config directives, such as mqtt_ports and mqtt_tls_ports. Network settings must be specified in the global section of the config file, not under any particular pubsub component. The default port is 1883 (MQTT’s standard port number) and 8883 for TLS connections.

Compatibility

sudo prosodyctl install --server=https://modules.prosody.im/rocks/ mod_pubsub_mqtt