MQTT Interface

MQTT Interface

Hubitat allows for opening and maintaining a connection to an MQTT broker from the hub. All code needs to be contained in a driver; there is no option to open an MQTT client connection from an app. Hubitat provides methods to connect and disconnect to the broker and subscribe and publish messages to topics. In addition, it is required to create a method in the driver that accepts incoming messages (parse) and another method that will be called with any status updates for the client connection (mqttClientStatus).

Hubitat-Provided Methods

These methods are available since platform 2.1.2.

connect

Signature

void connect(String broker, String clientId, String username, String password)

void connect(String broker, String clientId, String username, String password, options (name/value pairs))

Parameters

  • broker - The url of the broker to connect to.

  • clientId - The client id to use when connecting to the broker.

  • username - The username to use when connecting to the broker, use null if no username is necessary.

  • password - The password to use when connecting to the broker, use null if no password is necessary.

  • options - Optional parameters to configure the MQTT connection. Possible values:

    • byteInterface - defaults to 'false'. If set to true, messages are handled as byte arrays and will be hex string encoded.
    • lastWillTopic - The topic to publish to if connection is lost (Since 2.1.2)
    • lastWillQos - The qos to use for publishing last will message, possible values are 0,1 or 2 (Since 2.1.2)
    • lastWillMessage - The message to publish if connection is lost (Since 2.1.2)
    • lastWillRetain - Option to set last will message to retained, defaults to false (Since 2.1.2)
    • cleanSession - Option to set the clean_session flag for the connection (Since 2.2.2)
    • tlsVersion - The TLS version to use when connecting to broker, possible values are 1.0, 1.1, 1.2 Defaults to 1.2 if not specified (Since 2``.2.2)
    • caCertificate - The CA certificate for the TLS/SSL connection in PEM format (Since 2.2.2)
    • clientCertificate - The client certificate (X.509) for the TLS connection in PEM format. Optional but requires privateKey is specifed (Since 2.2.2)
    • privateKey - The private key for the TLS connection in PEM format. Optional but requires clientCertificate if specified (Since 2.2.2)

Examples

 // Connect to MQTT broker
 interfaces.mqtt.connect("tcp://test.mosquitto.org:1883", "mqtttest123", null, null)

 // Connect to MQTT broker with last will
 interfaces.mqtt.connect("tcp://test.mosquitto.org:1883",
                         "mqtttest456",
                         null,
                         null,
                         lastWillTopic: "/my/last/will",
                         lastWillQos: 0,
                         lastWillMessage: "I died")

 // connect to MQTT broker with TLS and certificate (AWS IOT Core)
 // Note, all 4 parameters (tlsVersion, privateKey, caCertificate, clientCertificate) are required for TLS secure connection
 // if any are missing the connection won't work or will fall back to non secure
 String clientCert = """-----BEGIN CERTIFICATE-----
 MIIDWjCCAkKgAwIBAgIVANPd/DAZc5xaB3y6tuyA4Vi2pdyfMA0GCSqGSIb3DQEB
 ...
 7qr3/l5YwtmArBPXAS4s60bfFwEVrLEpS9QPAIMnAFNWRkuwDNR1EZ3TcP12Ew==
 -----END CERTIFICATE-----"""

 String caCert = """-----BEGIN CERTIFICATE-----
 MIIEkjCCA3qgAwIBAgITBn+USionzfP6wq4rAfkI7rnExjANBgkqhkiG9w0BAQsF
 ...
 akcjMS9cmvqtmg5iUaQqqcT5NJ0hGA==
 -----END CERTIFICATE-----"""

 String privateKey = """-----BEGIN RSA PRIVATE KEY-----
 MIIEpQIBAAKCAQEA3D1ZquBWJDtLOpVlDwYHW0ayaE+T9ZPV/bq39NT1KaKG+1w3
 ...
 AeuFNEqh9ExHLMPw/McjOKQ+4oG42ZGox7WekbIWMt0CZvlbFYE0Ha0=
 -----END RSA PRIVATE KEY-----"""

 interfaces.mqtt.connect("ssl://q65g7jujvagsuy-ats.iot.us-east-2.amazonaws.com",
                         'testClient',
                          null,
                          null,
                          tlsVersion: "1.2",
                          privateKey: privateKey,
                          caCertificate: caCert,
                          clientCertificate: clientCert)

disconnect

Signature

void disconnect()

subscribe

Signature

void subscribe(String topicFilter, int qos = 1)

Parameters

topicFilter - The topic/filter to subscribe to.

qos - (optional, defaults to 1) The QoS to use when subscribing.

isConnected

Signature

boolean isConnected()

Returns

boolean - true if client is connected, false otherwise.

unsubscribe

Signature

void unsubscribe(String topicFilter)

Parameters

topicFilter - The topic filter to unsubscribe from.

publish

Signature

void publish(String topic, String payload, int qos = 1, boolean retained = false)

Parameters

topic - The topic to publish the message to.

payload - The body of the message.

qos - (optional, defaults to 1) The qos to use when publishing the message.

retained - (optional, defaults to false) Retain message in queue if subscriber is not listening.

parseMessage

Signature

Map parseMessage(String stringToParse)

Parameters

stringToParse - The string coming from the MQTT brokers subscribed topic.

Returns

Map - the string passed as a parameter is split into a Map and returned.

Examples

// parse message
interfaces.mqtt.parseMessage(description)

Hubitat-Provided Methods (Deprecated)

mqttConnect

Signature

void hubitat.helper.InterfaceUtils.alphaV1mqttConnect(DeviceWrapper device, String broker, String clientId, String username, String password)

void hubitat.helper.InterfaceUtils.alphaV1mqttConnect(DeviceWrapper device, String broker, String clientId, String username, String password, options (name/value pairs))

Parameters

  • device - The current device that is calling the method.
  • broker - The url of the broker to connect to.
  • clientId - The client id to use when connecting to the broker.
  • username - The username to use when connecting to the broker, use null if no username is necessary.
  • password - The password to use when connecting to the broker, use null if no password is necessary.
  • options - Optional parameters to configure the MQTT connection. Possible values:
    • byteInterface - defaults to 'false'. If set to true, messages are handled as byte arrays and will be hex string encoded.
    • lastWillTopic - The topic to publish to if connection is lost (Since 2.1.2)
    • lastWillQos - The qos to use for publishing last will message, possible values are 0,1 or 2 (Since 2.1.2)
    • lastWillMessage - The message to publish if connection is lost (Since 2.1.2)
    • lastWillRetain - Option to set last will message to retained, defaults to false (Since 2.1.2)

Examples

// ---
// DEPRECATED. Use new methods above for newer platform versions.
// ----
// Connect to MQTT broker
hubitat.helper.InterfaceUtils.alphaV1mqttConnect(device, "tcp://test.mosquitto.org:1883", "mqtttest123", null, null)
// Connect to MQTT broker with last will
hubitat.helper.InterfaceUtils.alphaV1mqttConnect(device, "tcp://test.mosquitto.org:1883", "mqtttest456", null, null, lastWillTopic: "/my/last/will", lastWillQos: 0, lastWillMessage: "I died")

mqttDisconnect

Signature

void hubitat.helper.InterfaceUtils.alphaV1mqttDisconnect(DeviceWrapper device)

Parameters

device - The current device that is calling the method.

mqttSubscribe

Signature

void hubitat.helper.InterfaceUtils.alphaV1mqttSubscribe(DeviceWrapper device, String topicFilter, int qos = 1)

Parameters

  • device - The current device that is calling the method.

  • topicFilter - The topic / filter to subscribe to.

  • qos - (optional, defaults to 1) The qos to use when subscribing.

mqttUnsubscribe

Signature

void hubitat.helper.InterfaceUtils.alphaV1mqttUnsubscribe(DeviceWrapper device, String topicFilter)

Parameters

device - The current device that is calling the method.

topicFilter - The topic filter to unsubscribe from.

mqttPublish

Signature

void hubitat.helper.InterfaceUtils.alphaV1mqttPublish(DeviceWrapper device, String topic, String payload, int qos = 1, boolean retained = false)

Parameters

device - The current device that is calling the method.

topic - The topic to publish the message to.

payload - The body of the message.

qos - (optional, defaults to 1) The qos to use when publishing the message.

retained - (optional, defaults to false) Retain message in queue if subscriber is not listening.

parseMqttMessage

Signature

Map hubitat.helper.InterfaceUtils.alphaV1parseMqttMessage(String stringToParse)

Parameters

stringToParse - The string coming from the MQTT brokers subscribed topic.

Returns

Map - the string passed as a parameter is split into a Map and returned.

User-Defined Methods

parse(String message)

This method is called with any incoming messages from the subscribed topics of the MQTT broker. This is a standard method for drivers.

mqttClientStatus(String message)

This method is called with any status messages from the MQTT client connection (disconnections, errors during connect, etc) The string that is passed to this method with start with "Error" if an error occurred or "Status" if this is just a status message.