本页目录

• Connector configuration: mqtt.json
  • Section “broker”
    • Subsection “security”
  • Section “mapping”
    • Subsection “converter”
  • Section “connectRequests”
  • Section “disconnectRequest”
  • Section “attributeRequests”
  • Section “attributeUpdates”
  • Server side RPC commands
• Next steps

This guide will help you to get familiar with MQTT Connector configuration for ThingsBoard IoT Gateway. Use general configuration to enable this Connector. The purpose of this Connector is to connect to external MQTT broker and subscribe to data feed from devices. Connector is also able to push data to MQTT brokers based on the updates/commands from ThingsBoard.

This Connector is useful when you have local MQTT broker in your facility or corporate network and you would like to push data from this broker to ThingsBoard.

We will describe connector configuration file below.

Connector configuration: mqtt.json

Connector configuration is a JSON file that contains information about how to connect to external MQTT broker, what topics to use when subscribing to data feed and how to process the data. Let’s review the format of the configuration file using example below.

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{
  "broker": {
    "name":"Default Local Broker",
    "host":"192.168.1.100",
    "port":1883,
    "security": {
      "type": "basic",
      "username": "user",
      "password": "password"
    }
  },
  "mapping": [
    {
      "topicFilter": "/sensor/data",
      "converter": {
        "type": "json",
        "deviceNameJsonExpression": "${serialNumber}",
        "deviceTypeJsonExpression": "${sensorType}",
        "timeout": 60000,
        "attributes": [
          {
            "type": "string",
            "key": "model",
            "value": "${sensorModel}"
          },
          {
            "type": "string",
            "key": "${sensorModel}",
            "value": "on"
          }
        ],
        "timeseries": [
          {
            "type": "double",
            "key": "temperature",
            "value": "${temp}"
          },
          {
            "type": "double",
            "key": "humidity",
            "value": "${hum}"
          },
          {
            "type": "string",
            "key": "combine",
            "value": "${hum}:${temp}"
          }
        ]
      }
    },
    {
      "topicFilter": "/sensor/+/data",
      "converter": {
        "type": "json",
        "deviceNameTopicExpression": "(?<=sensor\/)(.*?)(?=\/data)",
        "deviceTypeTopicExpression": "Thermometer",
        "timeout": 60000,
        "attributes": [
          {
            "type": "string",
            "key": "model",
            "value": "${sensorModel}"
          }
        ],
        "timeseries": [
          {
            "type": "double",
            "key": "temperature",
            "value": "${temp}"
          },
          {
            "type": "double",
            "key": "humidity",
            "value": "${hum}"
          }
        ]
      }
    },
    {
      "topicFilter": "/sensor/raw_data",
      "converter": {
        "type": "bytes",
        "deviceNameExpression": "[0:4]",
        "deviceTypeExpression": "default",
        "timeout": 60000,
        "attributes": [
          {
            "type": "raw",
            "key": "rawData",
            "value": "[:]"
          }
        ],
        "timeseries": [
          {
            "type": "raw",
            "key": "temp",
            "value": "[4:]"
          }
        ]
      }
    },
    {
      "topicFilter": "/custom/sensors/+",
      "converter": {
        "type": "custom",
        "extension": "CustomMqttUplinkConverter",
        "extension-config": {
            "temperatureBytes" : 2,
            "humidityBytes" :  2,
            "batteryLevelBytes" : 1
        }
      }
    }
  ],
  "connectRequests": [
    {
      "topicFilter": "/sensor/connect",
      "deviceNameJsonExpression": "${serialNumber}"
    },
    {
      "topicFilter": "/sensor/+/connect",
      "deviceNameTopicExpression": "(?<=sensor\/)(.*?)(?=\/connect)"
    }
  ],
  "disconnectRequests": [
    {
      "topicFilter": "/sensor/disconnect",
      "deviceNameJsonExpression": "${serialNumber}"
    },
    {
      "topicFilter": "/sensor/+/disconnect",
      "deviceNameTopicExpression": "(?<=sensor\/)(.*?)(?=\/disconnect)"
    }
  ],
  "attributeRequests": [
    {
      "retain": false,
      "topicFilter": "v1/devices/me/attributes/request",
      "topicExpression": "${SerialNumber}",
      "valueExpression": "${sensorModel}"
    }
  ],
  "attributeUpdates": [
    {
      "retain": false,
      "deviceNameFilter": "SN.*",
      "attributeFilter": "uploadFrequency",
      "topicExpression": "sensor/${deviceName}/${attributeKey}",
      "valueExpression": "{\"${attributeKey}\":\"${attributeValue}\"}"
    }
  ],
  "serverSideRpc": [
    {
      "deviceNameFilter": "SN.*",
      "methodFilter": "echo",
      "requestTopicExpression": "/sensor/${deviceName}/request/${methodName}/${requestId}",
      "responseTopicExpression": "/sensor/${deviceName}/response/${methodName}/${requestId}",
      "responseTimeout": 10000,
      "valueExpression": "${params}"
    },
    {
      "deviceNameFilter": ".*",
      "methodFilter": "no-reply",
      "requestTopicExpression": "/sensor/${deviceName}/request/${methodName}/${requestId}",
      "valueExpression": "${params.hum}::${params.temp}"
    }
  ]
}

Section “broker”

Subsection “security”

Subsection “security” provides configuration for client authorization at Mqtt Broker.

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    "security": {
      "type": "basic",
      "username": "username",
      "password": "password"
    }

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    "security": {
      "type": "anonymous"
    }

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  "security":{
    "caCert": "/etc/thingsboard-gateway/ca.pem",
    "privateKey": "/etc/thingsboard-gateway/privateKey.pem",
    "cert": "/etc/thingsboard-gateway/certificate.pem"
  }

Section “mapping”

This configuration section contains array of topics that the gateway will subscribe to after connecting to the broker and settings about processing incoming messages (converter).

The topicFilter supports special symbols: ‘#’ and ‘+’ to allow to subscribe to multiple topics.

Let’s assume we would like to subscribe and process following data from Thermometer devices:

In this case following messages are valid:

Example 1:

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mosquitto_pub -h YOUR_MQTT_BROKER_HOST -p YOUR_MQTT_BROKER_PORT -t "/sensor/data" -m '{"serialNumber": "SN-001", "sensorType": "Thermometer", "sensorModel": "T1000", "temp": 42, "hum": 58}'

Example 2:

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mosquitto_pub -h YOUR_MQTT_BROKER_HOST -p YOUR_MQTT_BROKER_PORT -t "/sensor/SN-001/data" -m '{"sensorType": "Thermometer", "sensorModel": "T1000", "temp": 42, "hum": 58}'

Now let’s review how we can configure JSON converter to parse this data

Subsection “converter”

This subsection contains configuration for processing incoming messages.

Types of mqtt converters:

1. json – Default converter
2. raw – Raw default converter
3. custom – Custom converter (You can write it by yourself, and it will use to convert incoming data from the broker.)

jsonRecommended if json will be received in response

bytesRecommended if bytes will be received in response

customRecommended if bytes or anything else will be received in response

Json converter is default converter, it looks for deviceName, deviceType, attributes and telemetry in the incoming message from the broker, with rules, described in this subsection: Parameter Default value 描述 type json Provides information to connector that default converter to be used for converting data from topic. deviceNameJsonExpression ${serialNumber} Simple JSON expression, uses for looking device name in the incoming message (parameter “serialNumber” will be used as device name). deviceTypeJsonExpression ${sensorType} Simple JSON expression, uses for looking device type in the incoming message (parameter “sensorType” will be used as device type). timeout 60000 Timeout for triggering “Device Disconnected” event attributes:   This subsection contains parameters of the incoming message, to be interpreted as attributes for the device. … type string Type of incoming data for a current attribute. … key model Attribute name, to be sent to ThingsBoard instance. … value ${sensorModel} Simple JSON expression, uses for looking value in the incoming message, to be sent to ThingsBoard instance as value of key parameter.       … type string Type of incoming data for a current attribute. … key ${sensorModel} Simple JSON expression, uses for looking value in the incoming message, to be used as attribute name. … value on Attribute value, to be sent to ThingsBoard instance. timeseries:   This subsection contains parameters of the incoming message, to be interpreted as telemetry for the device. … type double Type of incoming data for a current telemetry. … key temperature Telemetry name, to be sent to ThingsBoard instance. … value ${temp} Simple JSON expression, uses for looking value in the incoming message, to be sent to ThingsBoard instance as value of key parameter.       … type double Type of incoming data for a current telemetry. … key humidity Telemetry name, to be sent to ThingsBoard instance. … value ${hum} Simple JSON expression, uses for looking value in the incoming message, to be sent to ThingsBoard instance as value of key parameter. Parameters in attributes and telemetry section may differ from those presented above, but will have the same structure. Note: The device profile is set when the device is created. Changing the device profile using a Gateway is not provided. Mapping subsection for Example 1 will look like: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 { "topicFilter": "/sensor/data", "converter": { "type": "json", "deviceNameJsonExpression": "${serialNumber}", "deviceTypeJsonExpression": "${sensorType}", "timeout": 60000, "attributes": [ { "type": "string", "key": "model", "value": "${sensorModel}" }, { "type": "string", "key": "${sensorModel}", "value": "on" } ], "timeseries": [ { "type": "double", "key": "temperature", "value": "${temp}" }, { "type": "double", "key": "humidity", "value": "${hum}" } ] } } Mapping for Example 2 will look like: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 { "topicFilter": "/sensor/+/data", "converter": { "type": "json", "deviceNameTopicExpression": "(?<=sensor\/)(.*?)(?=\/data)", "deviceTypeTopicExpression": "Thermometer", "timeout": 60000, "attributes": [ { "type": "string", "key": "model", "value": "${sensorModel}" } ], "timeseries": [ { "type": "double", "key": "temperature", "value": "${temp}" }, { "type": "double", "key": "humidity", "value": "${hum}" } ] } }

Bytes converter is default converter, it looks for deviceName, deviceType, attributes and telemetry in the incoming message from the broker, with rules, described in this subsection: Parameter Default value 描述 type bytes Provides information to connector that default converter to be used for converting data from topic. deviceNameExpression [0:4] The expression that is used to find device name in the incoming message. deviceTypeExpression [1:3] The expression that is used to find device type in the incoming message. timeout 60000 Timeout for triggering “Device Disconnected” event. attributes:   This subsection contains parameters of the incoming message, to be interpreted as attributes for the device. … type raw Type of incoming data for a current attribute. … key temp Attribute name, to be sent to ThingsBoard instance. … value [:] Final view of data that will be sent to ThingsBoard, [:] - will replace to device data using python slice rules. timeseries:   This subsection contains parameters of the incoming message, to be interpreted as telemetry for the device. … type raw Type of incoming data for a current telemetry. … key rawData Telemetry name, to be sent to ThingsBoard instance. … value [4:] Final view of data that will be sent to ThingsBoard, [:] - will replace to device data using python slice rules. Parameters in attributes and telemetry section may differ from those presented above, but will have the same structure. Note: The device profile is set when the device is created. Changing the device profile using a Gateway is not provided. Mapping subsection will look like: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 { "topicFilter": "/sensor/raw_data", "converter": { "type": "bytes", "deviceNameExpression": "[0:4]", "deviceTypeExpression": "default", "timeout": 60000, "attributes": [ { "type": "raw", "key": "rawData", "value": "[:]" } ], "timeseries": [ { "type": "raw", "key": "temp", "value": "[4:]" } ] } }

A custom converter is converter written for some device: Parameter Default value 描述 type custom Provides information to connector that custom converter will be uses for converting data from topic. extension CustomMqttUplinkConverter Name of custom converter class. extension-config   This subsection is a configuration for the custom converter. In default example it contains number of bytes and keys for telemetry. temperatureBytes 2 In default example first 2 bytes from received message will be interpreted as temperature key of telemetry (Substring “Bytes” will remove if exists). humidityBytes 2 In default example the second and third byte from received message will be interpreted as humidity key of telemetry (Substring “Bytes” will remove if exists). batteryLevelBytes 1 In default example the fifth byte from received message will be interpreted as batteryLevel key of telemetry (Substring “Bytes” will removed if exists). All parameters from this subsection and topic will be transferred as dictionary during initialization to the converter object. Converter subsection in the configuration will look like: 1 2 3 4 5 6 7 8 9 "converter": { "type": "custom", "extension": "CustomMqttUplinkConverter", "extension-config": { "temperatureBytes" : 2, "humidityBytes" : 2, "batteryLevelBytes" : 1 } }

Note: You can specify multiple mapping objects inside the array.

Also, you can combine values from MQTT message in attributes, telemetry and serverSideRpc section, for example:

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{
  {
      "topicFilter": "/sensor/data",
      "converter": {
        "type": "json",
        "deviceNameJsonExpression": "${serialNumber}",
        "deviceTypeJsonExpression": "${sensorType}",
        "timeout": 60000,
        "attributes": [],
        "timeseries": [
          {
            "type": "double",
            "key": "temperature",
            "value": "${temp}"
          },
          {
            "type": "double",
            "key": "humidity",
            "value": "${hum}"
          },
          {
            "type": "string",
            "key": "combine",
            "value": "${hum}:${temp}"
          }
        ]
      }
    }
}

Mapping process subscribes to the MQTT topics using topicFilter parameter of the mapping object. Each message that is published to this topic by other devices or applications is analyzed to extract device name, type and data (attributes and/or timeseries values). By default, gateway uses Json converter, but it is possible to provide custom converter. See examples in the source code.

Connector won’t pass the None value from the converter

Now let’s review an example of sending data from “SN-001” thermometer device.

Let’s assume MQTT broker is installed locally on your server.

Use terminal to simulate sending message from the device to the MQTT broker:

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mosquitto_pub -h 127.0.0.1 -p 1883 -t "/sensor/data" -m '{"serialNumber": "SN-001", "sensorType": "Thermometer", "sensorModel": "T1000", "temp": 42, "hum": 58}'

The device will be created and displayed in ThingsBoard based on the passed parameters.

Section “connectRequests”

ThingsBoard allows sending RPC commands and notifications about device attribute updates to the device. But in order to send them, the platform needs to know if the target device is connected and what gateway or session is used to connect the device at the moment. If your device is constantly sending telemetry data - ThingsBoard already knows how to push notifications. If your device just connects to MQTT broker and waits for commands/updates, you need to send a message to the Gateway and inform that device is connected to the broker.

1. Name in a message from broker:

2. Name in topic address:

This section in configuration looks like:

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  "connectRequests": [
    {
      "topicFilter": "/sensor/connect",
      "deviceNameJsonExpression": "${serialNumber}"
    },
    {
      "topicFilter": "/sensor/+/connect",
      "deviceNameTopicExpression": "(?<=sensor\/)(.*?)(?=\/connect)"
    }
  ]

In this case following messages are valid:

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mosquitto_pub -h YOUR_MQTT_BROKER_HOST -p YOUR_MQTT_BROKER_PORT -t "/sensor/connect" -m '{"serialNumber":"SN-001"}'

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mosquitto_pub -h YOUR_MQTT_BROKER_HOST -p YOUR_MQTT_BROKER_PORT -t "/sensor/SN-001/connect" -m ''

Now let’s review an example.

Use a terminal to simulate sending a message from the device to the MQTT broker:

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mosquitto_pub -h 127.0.0.1 -p 1883 -t "/sensor/connect" -m '{"serialNumber": "SN-001"}'

Your ThingsBoard instance will get information from the broker about last connecting time of the device. You can see this information on the “Server attributes” scope (“Attributes” tab).

Section “disconnectRequest”

This configuration section is optional.
Configuration, provided in this section will be used to get information from the broker about disconnecting device.
If your device just disconnects from MQTT broker and waits for commands/updates, you need to send a message to the Gateway and inform that device is disconnected from the broker.

1. Name in a message from broker:

2. Name in topic address:

This section in configuration file looks like:

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  "disconnectRequests": [
    {
      "topicFilter": "/sensor/disconnect",
      "deviceNameJsonExpression": "${serialNumber}"
    },
    {
      "topicFilter": "/sensor/+/disconnect",
      "deviceNameTopicExpression": "(?<=sensor\/)(.*?)(?=\/disconnect)"
    }
  ]

In this case following messages are valid:

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mosquitto_pub -h YOUR_MQTT_BROKER_HOST -p YOUR_MQTT_BROKER_PORT -t "/sensor/disconnect" -m '{"serialNumber":"SN-001"}'

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mosquitto_pub -h YOUR_MQTT_BROKER_HOST -p YOUR_MQTT_BROKER_PORT -t "/sensor/SN-001/disconnect" -m ''

Now let’s review an example.

Use a terminal to simulate sending a message from the device to MQTT broker:

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mosquitto_pub -h 127.0.0.1 -p 1883 -t "/sensor/disconnect" -m '{"serialNumber": "SN-001"}'

Your ThingsBoard instance will get information from the broker about last disconnecting time of the device. You can see this information on the “Server attributes” scope (“Attributes” tab).

Section “attributeRequests”

Configuration in this section are optional.

In order to request client-side or shared device attributes to ThingsBoard server node, Gateway allows sending attribute requests.

This section in configuration file looks like:

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"attributeRequests": [
  {
    "retain": false,
    "topicFilter": "v1/devices/me/attributes/request",
    "deviceNameJsonExpression": "${serialNumber}",
    "attributeNameJsonExpression": "${versionAttribute}",
    "topicExpression": "devices/${deviceName}/attrs",
    "valueExpression": "${attributeKey}: ${attributeValue}"
  }
]

Also, you can request multiple attributes at once. Simply add one more JSON-path to attributeNameExpression parameter. For example, we want to request two shared attributes in one request, our config will look like:

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"attributeRequests": [
  {
    "retain": false,
    "topicFilter": "v1/devices/me/attributes/request",
    "deviceNameJsonExpression": "${serialNumber}",
    "attributeNameJsonExpression": "${versionAttribute}, ${pduAttribute}",
    "topicExpression": "devices/${deviceName}/attrs",
    "valueExpression": "${attributeKey}: ${attributeValue}"
  }
]

Section “attributeUpdates”

This configuration section is optional.
ThingsBoard allows to provision device attributes and fetch some of them from the device application. You can treat this as a remote configuration for devices. Your devices are able to request shared attributes from ThingsBoard. See user guide for more details.

The “attributeRequests” configuration allows configuring the format of the corresponding attribute request and response messages.

This section in configuration file looks like:

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  "attributeUpdates": [
    {
      "retain": false,
      "deviceNameFilter": "SN.*",
      "attributeFilter": "uploadFrequency",
      "topicExpression": "/sensor/${deviceName}/${attributeKey}",
      "valueExpression": "{\"${attributeKey}\":\"${attributeValue}\"}"
    }
  ]

Let’s look at an example.

Run the command below. You will start the mosquitto_sub client that subscribes to the topic “/sensor/SN-001/FirmwareVersion” of the local broker and start waiting for new messages from ThingsBoard server to broker.

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mosquitto_sub -t /sensor/SN-001/FirmwareVersion

Update device attribute value on the ThingsBoard server. Open Devices -> click by your device -> Attributes tab -> Shared attributes scope and click on the “pencil” button next to “FirmwareVersion” attribute.

Change firmware version value from “1.1” to “1.2”. Then click “Update” button.

The firmware version has been updated to “1.2”.

Broker received new message from the ThingsBoard server about updating attribute “FirmwareVersion” to “1.2”.

Server side RPC commands

ThingsBoard allows sending RPC commands to the device that is connected to ThingsBoard directly or via Gateway.

Configuration, provided in this section uses for sending RPC requests from ThingsBoard to device.

There are 2 options for RPC request:

1. With response – If in the configuration exists responseTopicExpression, gateway will try to subscribe on it and wait for response.
2. Without response – If in the configuration not exists responseTopicExpression, gateway have just send message and won’t wait for response.

This section in configuration file looks like:

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  "serverSideRpc": [
    {
      "deviceNameFilter": "SN.*",
      "methodFilter": "echo",
      "requestTopicExpression": "/sensor/${deviceName}/request/${methodName}/${requestId}",
      "responseTopicExpression": "/sensor/${deviceName}/response/${methodName}/${requestId}",
      "responseTimeout": 10000,
      "valueExpression": "${params}"
    },
    {
      "deviceNameFilter": ".*",
      "methodFilter": "no-reply",
      "requestTopicExpression": "/sensor/${deviceName}/request/${methodName}/${requestId}",
      "valueExpression": "${params.hum}::${params.temp}"
    }
  ]

As you can use deviceNameFilter and methodFilter to apply different mapping rules for different devices/methods. Once Gateway receives RPC request from the server to the device, it will publish the corresponding message based on requestTopicExpression and valueExpression. In case you expect the reply to the request from device, you should also specify responseTopicExpression and responseTimeout. The Gateway will subscribe to the “response” topic and wait for device reply until “responseTimeout” is detected (in milliseconds).

Example of RPC request (rpc-request.json) that need to be sent from the server:

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{
  "method": "echo",
  "params": {
    "message": "Hello!"
  }
}

Also, every telemetry and attribute parameter has built-in GET and SET RPC methods out of the box, so you don’t need to configure it manually. To use them, make sure you set all required parameters (in the case of MQTT Connector, these are the following: requestTopicExpression, responseTopicExpression, responseTimeout, valueExpression). See the guide.

Next steps

Explore guides related to main ThingsBoard features:

• Data Visualization - how to visualize collected data.
• Device attributes - how to use device attributes.
• Telemetry data collection - how to collect telemetry data.
• Using RPC capabilities - how to send commands to/from devices.
• Rule Engine - how to use rule engine to analyze data from devices.