# MQTT Historian

## Overview

The MQTT Historian agent publishes data to an MQTT broker.

The mqttlistener.py script will connect to the broker and print all
messages.

## Dependencies

The Paho MQTT library from Eclipse is needed for the agent and can be
installed with:

    pip install paho-mqtt

The Mosquitto MQTT broker may be useful for testing and can be installed
with

    apt-get install mosquitto

## Configuration

The following is an example configuration file:

    {
        "connection: {
            # Optional backup limit in gigabytes. Default is no backup limit.
            # "backup_storage_limit_gb": null,
    
            # Quality of service level for MQTT publishes. Default is 0.
            # "mqtt_qos": 0,
    
            # Set messages to be retained. Default is False
            # "mqtt_retain": false,
    
            # Address of broker to connect to. Default is localhost.
            "mqtt_hostname": "localhost",
    
            # Port on broker accepting connections. Default is 1883
            "mqtt_port": 1883
    
            # If a client id is not provided one will be generated by paho-mqtt.
            # Default is an empty string.
            # "mqtt_client_id": "",
    
            # Keepalive timeout for the client. Default is 60 seconds
            # "mqtt_keepalive": 60,
    
            # Optional will is published when the client disconnects. Default is None.
            # If used then QOS defaults to 0 and retain defaults to False.
            # "mqtt_will": {
            #     "topic": "<topic>",
            #     "payload":"<payload">,
            #     "qos":<qos>,
            #     "retain":<retain>
            # },
    
            # MQTT authentication info. Defaults to None.
            # "mqtt_auth": {
            #    "username": "<username>",
            #    "password": "<password>"
            # },
    
            # MQTT TLS parameters. If used then CA Certs is required. Otherwise the
            # default is None.
            # "mqtt_tls": {
            #     "ca_certs":"<ca_certs>",
            #     "certfile":"<certfile>",
            #     "keyfile":"<keyfile>",
            #     "tls_version":"<tls_version>",
            #     "ciphers":"<ciphers">
            # }
    
            # Protocol versions MQTTv311 and MQTTv31 are supported. Default is MQTTv311.
            # "mqtt_protocol": "MQTTv311"
        }
    }