Request Connector Configuration

Connector configuration: request.json
Next steps

This guide will help you to get familiar with Request Connector configuration for ThingsBoard IoT Gateway.
Use general configuration guide to enable this Connector.
The purpose of this Connector is to connect to external HTTP(S) API endpoints and get data from them.
Connector is also able to push data to external HTTP(S) API based on the updates/commands from ThingsBoard.

This connector is useful when you have some HTTP(S) API endpoints in your device or some data in external resource and you would like to push this data to the ThingsBoard.

We will describe connector configuration file below.

Connector configuration: request.json

Connector configuration is a JSON file that contains information about how to connect to external API endpoints, what urls to use when reading data and how to process the data.
Let’s review the format of the configuration file using example below.

Example of Request Connector config file. Press to expand.

Example listed below will connect to server on a localhost with 5000 port. Connector will use basic HTTP authorization using username and password. Then, connector will read data from a list of endpoints using urls from mapping section. See more info in a description below.

{
  "host": "http://127.0.0.1:5000",
  "SSLVerify": true,
  "security": {
    "type": "basic",
    "username": "user",
    "password": "password"
  },
  "mapping": [
    {
      "url": "getdata",
      "httpMethod": "GET",
      "httpHeaders": {
        "ACCEPT": "application/json"
      },
      "allowRedirects": true,
      "timeout": 0.5,
      "scanPeriod": 5,
      "converter": {
        "type": "json",
        "deviceNameJsonExpression": "SD8500",
        "deviceTypeJsonExpression": "SD",
        "attributes": [
          {
            "key": "serialNumber",
            "type": "string",
            "value": "${serial}"
          }
        ],
        "telemetry": [
          {
            "key": "Maintainer",
            "type": "string",
            "value": "${Developer}"
          }
        ]
      }
    },
    {
      "url": "get_info",
      "httpMethod": "GET",
      "httpHeaders": {
        "ACCEPT": "application/json"
      },
      "allowRedirects": true,
      "timeout": 0.5,
      "scanPeriod": 100,
      "converter": {
        "type": "custom",
        "deviceNameJsonExpression": "SD8500",
        "deviceTypeJsonExpression": "SD",
        "extension": "CustomRequestUplinkConverter",
        "extension-config": [
          {
            "key": "Totaliser",
            "type": "float",
            "fromByte": 0,
            "toByte": 4,
            "byteorder": "big",
            "signed": true,
            "multiplier": 1
          },
          {
            "key": "Flow",
            "type": "int",
            "fromByte": 4,
            "toByte": 6,
            "byteorder": "big",
            "signed": true,
            "multiplier": 0.01
          }
        ]
      }
    }
  ],
  "attributeUpdates": [
      {
        "httpMethod": "POST",
        "httpHeaders": {
          "CONTENT-TYPE": "application/json"
        },
        "timeout": 0.5,
        "tries": 3,
        "allowRedirects": true,
        "deviceNameFilter": "SD.*",
        "attributeFilter": "send_data",
        "requestUrlExpression": "sensor/${deviceName}/${attributeKey}",
        "valueExpression": "{\"${attributeKey}\":\"${attributeValue}\"}"
      }
  ],
  "serverSideRpc": [
    {
      "deviceNameFilter": ".*",
      "methodFilter": "echo",
      "requestUrlExpression": "sensor/${deviceName}/request/${methodName}/${requestId}",
      "responseTimeout": 1,
      "httpMethod": "GET",
      "valueExpression": "${params}",
      "timeout": 0.5,
      "tries": 3,
      "httpHeaders": {
        "Content-Type": "application/json"
      }
    },
    {
      "deviceNameFilter": ".*",
      "methodFilter": "no-reply",
      "requestUrlExpression": "sensor/${deviceName}/request/${methodName}/${requestId}",
      "httpMethod": "POST",
      "valueExpression": "${params}",
      "httpHeaders": {
        "Content-Type": "application/json"
      }
    }
  ]
}

General section

参数	Default value	描述
host	http://127.0.0.1:5000	Domain address or ip of the server.
SSLVerify	true	Verify or no SSL certificate on the server if available.

Security section

This section provides configuration for client authorization at the external server.

BasicRecommended

AnonymousNo security

One type of security configuration is Basic authentication. The Request Connector sends HTTP requests with the Authorization header that contains the word Basic word followed by a space and a base64-encoded string username:password.

Parameter	Default value	描述
type	basic	Type of authorization.
username	username	Username for authorization.
password	password	Password for authorization.

Security section in configuration file will look like this:

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

Anonymous auth is the most simple option. It is useful for testing.

Parameter	Default value	描述
type	anonymous	Type of authorization.

Security subsection in configuration file will look like this:

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

Mapping section

This configuration section contains array of objects with endpoints that the gateway will try to read after connecting to the server.
Also this section contains settings about processing incoming messages (converter).
After request, each response from that url is analyzed to extract device name, type and data (attributes and/or timeseries values).
By default, the gateway uses Json converter, but it is possible to provide custom converter. See example in the source code.

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

参数	Default value	描述
url	getdata	Url address for sending request.
httpMethod	GET	HTTP method for request (GET, POST etc.).
httpHeaders	{ “ACCEPT”: “application/json” }	Object contains additional HTTP headers for request.
allowRedirects	true	Allow request redirection.
timeout	0.5	Timeout for request.
scanPeriod	5	Rescan rate.

Converter subsection

This subsection contains configuration for processing incoming messages.

Types of request converters:

json – Default converter
custom – Custom converter (You can write it by yourself, and it will use to convert incoming data from the 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 will be uses for converting data from response.
deviceNameJsonExpression	SD8500	Simple JSON expression, uses for looking device name in the incoming message (string “SD8500” will be used as device name).
deviceTypeJsonExpression	SD	Simple JSON expression, uses for looking device type in the incoming message (string “SD” will be used as device type).
timeout	60000	Timeout for triggering “Device Disconnected” event
attributes		This subsection contains parameters of the incoming message, that will be interpreted as attributes for the device.
… type	string	Type of incoming data for a current attribute.
… key	serialNumber	Attribute name, that will sends to ThingsBoard instance.
… value	${serial}	Simple JSON expression, uses for looking value in the incoming message, that will send to ThingsBoard instance as value of key parameter.
timeseries		This subsection contains parameters of the incoming message, that will be interpreted as telemetry for the device.
… type	string	Type of incoming data for a current telemetry.
… key	Maintainer	Telemetry name, that will sends to ThingsBoard instance.
… value	${Developer}	Simple JSON expression, uses for looking value in the incoming message, that will send to ThingsBoard instance as value of key parameter.

Mapping subsection will look like:

    {
      "url": "getdata",
      "httpMethod": "GET",
      "httpHeaders": {
        "ACCEPT": "application/json"
      },
      "allowRedirects": true,
      "timeout": 0.5,
      "scanPeriod": 5,
      "converter": {
        "type": "json",
        "deviceNameJsonExpression": "SD8500",
        "deviceTypeJsonExpression": "SD",
        "attributes": [
          {
            "key": "serialNumber",
            "type": "string",
            "value": "${serial}"
          }
        ],
        "telemetry": [
          {
            "key": "Maintainer",
            "type": "string",
            "value": "${Developer}"
          }
        ]
      }
    }

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

{
      "url": "getdata",
      "httpMethod": "GET",
      "httpHeaders": {
        "ACCEPT": "application/json"
      },
      "allowRedirects": true,
      "timeout": 0.5,
      "scanPeriod": 5,
      "converter": {
        "type": "json",
        "deviceNameJsonExpression": "SD8500",
        "deviceTypeJsonExpression": "SD",
        "attributes": [],
        "telemetry": [
          {
            "type": "double",
            "key": "temperature",
            "value": "${temp}"
          },
          {
            "type": "double",
            "key": "humidity",
            "value": "${hum}"
          },
          {
            "type": "string",
            "key": "combine",
            "value": "${hum}:${temp}"
          }
        ]
      }
    }

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 response.
extension	CustomRequestUplinkConverter	Name of custom converter class.
extension-config		This subsection is a configuration for the custom converter. In default example it contains setting for parsing response string.
key	Totaliser	In this example value “Totaliser” will be interpreted as a telemetry key in ThingsBoard instance.
type	float	In this example type of the data.
fromByte	0	In this example start byte position in the response string.
toByte	4	In this example start byte position in the response string.
byteorder	big	In this example byteorder for response string.
signed	true	In this example using to indicate is the data in response signed.
multiplier	1	In this example every data from in response should be multiplied to some coefficient.

Mapping subsection in the configuration will look like:

    {
      "url": "get_info",
      "httpMethod": "GET",
      "httpHeaders": {
        "ACCEPT": "application/json"
      },
      "allowRedirects": true,
      "timeout": 0.5,
      "scanPeriod": 100,
      "converter": {
        "type": "custom",
        "deviceNameJsonExpression": "SD8500",
        "deviceTypeJsonExpression": "SD",
        "extension": "CustomRequestUplinkConverter",
        "extension-config": [
          {
            "key": "Totaliser",
            "type": "float",
            "fromByte": 0,
            "toByte": 4,
            "byteorder": "big",
            "signed": true,
            "multiplier": 1
          },
          {
            "key": "Flow",
            "type": "int",
            "fromByte": 4,
            "toByte": 6,
            "byteorder": "big",
            "signed": true,
            "multiplier": 0.01
          }
        ]
      }
    }

Attribute update section

Configuration in this section are 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.

参数	Default value	描述
httpMethod	GET	HTTP method for request (GET, POST etc.).
httpHeaders	{ “CONTENT-TYPE”: “application/json” }	Object contains additional HTTP headers for request.
timeout	0.5	Timeout for request.
tries	3	Count of tries to send data
allowRedirects	true	Allow request redirection.
deviceNameFilter	SD.*	Regular expression device name filter, uses to determine, which function to execute.
attributeFilter	send_data	Regular expression attribute name filter, uses to determine, which function to execute.
requestUrlExpression	sensor/${deviceName}/${attributeKey}	JSON-path expression uses for creating url address to send a message.
valueExpression	{\”${attributeKey}\”:\”${attributeValue}\”}	JSON-path expression uses for creating the message data that will send to url.

The attributeUpdates section will look like:

  "attributeUpdates": [
      {
        "httpMethod": "POST",
        "httpHeaders": {
          "CONTENT-TYPE": "application/json"
        },
        "timeout": 0.5,
        "tries": 3,
        "allowRedirects": true,
        "deviceNameFilter": "SD.*",
        "attributeFilter": "send_data",
        "requestUrlExpression": "sensor/${deviceName}/${attributeKey}",
        "valueExpression": "{\"${attributeKey}\":\"${attributeValue}\"}"
      }
  ]

Server side RPC section

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.

参数	Default value	描述
deviceNameFilter	SmartMeter.*	Regular expression device name filter, uses to determine, which function to execute.
methodFilter	echo	Regular expression method name filter, uses to determine, which function to execute.
requestUrlExpression	sensor/${deviceName}/request/${methodName}/${requestId}	JSON-path expression, uses to create url address to send RPC request.
responseTimeout	0.5	Timeout for request.
httpMethod	GET	HTTP method for request (GET, POST etc.).
valueExpression	${params}	JSON-path expression, uses for creating data for sending to the external endpoint.
timeout	0.5	Timeout for request.
tries	3	Count of tries to send data
httpHeaders	{ “CONTENT-TYPE”: “application/json” }	Object contains additional HTTP headers for request.

  "serverSideRpc": [
    {
      "deviceNameFilter": ".*",
      "methodFilter": "echo",
      "requestUrlExpression": "sensor/${deviceName}/request/${methodName}/${requestId}",
      "responseTimeout": 1,
      "httpMethod": "GET",
      "valueExpression": "${params}",
      "timeout": 0.5,
      "tries": 3,
      "httpHeaders": {
        "Content-Type": "application/json"
      }
    },
    {
      "deviceNameFilter": ".*",
      "methodFilter": "no-reply",
      "requestUrlExpression": "sensor/${deviceName}/request/${methodName}/${requestId}",
      "httpMethod": "POST",
      "valueExpression": "${params.hum}",
      "httpHeaders": {
        "Content-Type": "application/json"
      }
    }
  ]

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.

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