On this page

• Getting started
  • HTTP basics
  • Client libraries setup
  • HTTP Authentication and error codes
• Key-value format
• Telemetry upload API
• Attributes API
  • Publish attribute update to the server
  • Request attribute values from the server
  • Subscribe to attribute updates from the server
• JSON value support
• RPC API
  • Server-side RPC
  • Client-side RPC
• Claiming devices
• Device provisioning
• Firmware API
• Protocol customization
• Next steps

Getting started

HTTP basics

HTTP is a general-purpose network protocol that can be used in IoT applications. You can find more information about HTTP here. HTTP protocol is TCP based and uses request-response model.

IoT Hub server nodes act as an HTTP Server that supports both HTTP and HTTPS protocols.

Client libraries setup

You can find HTTP client libraries for different programming languages on the web. Examples in this article will be based on curl. In order to setup this tool, you can use instructions in our Hello World guide.

HTTP Authentication and error codes

We will use access token device credentials in this article and they will be referred to later as $ACCESS_TOKEN. The application needs to include $ACCESS_TOKEN as a path parameter in each HTTP request. Possible error codes and their reasons:

• 400 Bad Request - Invalid URL, request parameters or body.
• 401 Unauthorized - Invalid $ACCESS_TOKEN.
• 404 Not Found - Resource not found.

Key-value format

By default, IoT Hub supports key-value content in JSON. Key is always a string, while value can be either string, boolean, double, long or JSON. For example:

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{
 "stringKey":"value1", 
 "booleanKey":true, 
 "doubleKey":42.0, 
 "longKey":73, 
 "jsonKey": {
    "someNumber": 42,
    "someArray": [1,2,3],
    "someNestedObject": {"key": "value"}
 }
}

Using custom binary format or some serialization framework is also possible. See protocol customization for more details.

Telemetry upload API

In order to publish telemetry data to IoT Hub server node, send POST request to the following URL:

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http(s)://host:port/api/v1/$ACCESS_TOKEN/telemetry

The simplest supported data formats are:

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{"key1":"value1", "key2":"value2"}

or

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[{"key1":"value1"}, {"key2":"value2"}]

Please note that in this case, the server-side timestamp will be assigned to uploaded data!

In case your device is able to get the client-side timestamp, you can use following format:

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{"ts":1451649600512, "values":{"key1":"value1", "key2":"value2"}}

In the example above, we assume that “1451649600512” is a unix timestamp with milliseconds precision. For example, the value ‘1451649600512’ corresponds to ‘Fri, 01 Jan 2016 12:00:00.512 GMT’

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# for IoT Hub

# Publish data as an object without timestamp (server-side timestamp will be used)
curl -v -X POST --data "{"temperature":42,"humidity":73}" https://iothub.magenta.at/api/v1/$ACCESS_TOKEN/telemetry --header "Content-Type:application/json"
# Publish data as an object without timestamp (server-side timestamp will be used) using data from file
curl -v -X POST -d @telemetry-data-as-object.json https://iothub.magenta.at/api/v1/$ACCESS_TOKEN/telemetry --header "Content-Type:application/json"
# Publish data as an array of objects without timestamp (server-side timestamp will be used)  using data from file
curl -v -X POST -d @telemetry-data-as-array.json https://iothub.magenta.at/api/v1/$ACCESS_TOKEN/telemetry --header "Content-Type:application/json"
# Publish data as an object with timestamp (telemetry timestamp will be used)  using data from file
curl -v -X POST -d @telemetry-data-with-ts.json https://iothub.magenta.at/api/v1/$ACCESS_TOKEN/telemetry --header "Content-Type:application/json"

# for local IoT Hub

# Publish data as an object without timestamp (server-side timestamp will be used)
curl -v -X POST --data "{"temperature":42,"humidity":73}" http://localhost:8080/api/v1/$ACCESS_TOKEN/telemetry --header "Content-Type:application/json"
# Publish data as an object without timestamp (server-side timestamp will be used)  using data from file
curl -v -X POST -d @telemetry-data-as-object.json http://localhost:8080/api/v1/$ACCESS_TOKEN/telemetry --header "Content-Type:application/json"
# Publish data as an array of objects without timestamp (server-side timestamp will be used)  using data from file
curl -v -X POST -d @telemetry-data-as-array.json http://localhost:8080/api/v1/$ACCESS_TOKEN/telemetry --header "Content-Type:application/json"
# Publish data as an object with timestamp (telemetry timestamp will be used)  using data from file
curl -v -X POST -d @telemetry-data-with-ts.json http://localhost:8080/api/v1/$ACCESS_TOKEN/telemetry --header "Content-Type:application/json"

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{
  "stringKey": "value1",
  "booleanKey": true,
  "doubleKey": 42.0,
  "longKey": 73,
  "jsonKey": {
    "someNumber": 42,
    "someArray": [1,2,3],
    "someNestedObject": {"key": "value"}
  }
}

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[{"key1":"value1"}, {"key2":true}]

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{
  "ts": 1451649600512,
  "values": {
    "stringKey": "value1",
    "booleanKey": true,
    "doubleKey": 42.0,
    "longKey": 73,
    "jsonKey": {
      "someNumber": 42,
      "someArray": [1, 2, 3],
      "someNestedObject": {
        "key": "value"
      }
    }
  }
}

Attributes API

IoT Hub attributes API allows devices to

• Upload client-side device attributes to the server.
• Request client-side and shared device attributes from the server.
• Subscribe to shared device attributes from the server.

Publish attribute update to the server

In order to publish client-side device attributes to IoT Hub server node, send POST request to the following URL:

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http(s)://host:port/api/v1/$ACCESS_TOKEN/attributes

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# for IoT Hub

# Publish client-side attributes update
curl -v -X POST --data "{"attribute1": "value1", "attribute2":true, "attribute3": 43.0}" https://iothub.magenta.at/api/v1/$ACCESS_TOKEN/attributes --header "Content-Type:application/json"
# Publish client-side attributes update from file
curl -v -X POST -d @new-attributes-values.json https://iothub.magenta.at/api/v1/$ACCESS_TOKEN/attributes --header "Content-Type:application/json"

# for local IoT Hub

# Publish client-side attributes update
curl -v -X POST --data "{"attribute1": "value1", "attribute2":true, "attribute3": 43.0}" http://localhost:8080/api/v1/$ACCESS_TOKEN/attributes --header "Content-Type:application/json"
# Publish client-side attributes update from file
curl -v -X POST -d @new-attributes-values.json http://localhost:8080/api/v1/$ACCESS_TOKEN/attributes --header "Content-Type:application/json"

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{
  "attribute1": "value1",
  "attribute2": true,
  "attribute3": 42.0,
  "attribute4": 73,
  "attribute5": {
    "someNumber": 42,
    "someArray": [1,2,3],
    "someNestedObject": {"key": "value"}
  }
}

Request attribute values from the server

In order to request client-side or shared device attributes to IoT Hub server node, send GET request to the following URL:

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http(s)://host:port/api/v1/$ACCESS_TOKEN/attributes?clientKeys=attribute1,attribute2&sharedKeys=shared1,shared2

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# for IoT Hub

# Send HTTP attributes request
curl -v -X GET "https://iothub.magenta.at/api/v1/$ACCESS_TOKEN/attributes?clientKeys=attribute1,attribute2&sharedKeys=shared1,shared2"

# for local IoT Hub

# Send HTTP attributes request
curl -v -X GET http://localhost:8080/api/v1/$ACCESS_TOKEN/attributes?clientKeys=attribute1,attribute2&sharedKeys=shared1,shared2

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{"key1":"value1"}

Please note, the intersection of client-side and shared device attribute keys is a bad practice! However, it is still possible to have same keys for client, shared or even server-side attributes.

Subscribe to attribute updates from the server

In order to subscribe to shared device attribute changes, send GET request with optional “timeout” request parameter to the following URL:

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http(s)://host:port/api/v1/$ACCESS_TOKEN/attributes/updates

Once shared attribute will be changed by one of the server-side components (REST API or Rule Chain) the client will receive the following update:

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# for IoT Hub

# Send HTTP attributes request
curl -v -X GET https://iothub.magenta.at/api/v1/$ACCESS_TOKEN/attributes/updates?timeout=20000

# for local IoT Hub

# Send subscribe attributes request with 20 seconds timeout
curl -v -X GET http://localhost:8080/api/v1/$ACCESS_TOKEN/attributes/updates?timeout=20000

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{"key1":"value1"}

JSON value support

We added support of JSON data structures to telemetry and attributes API to simplify work with device configuration. JSON support allows you to both upload from the device, and push to device nested objects. You can store one configuration JSON as a shared attribute and push it to the device. You can also process the JSON data in the rule engine and raise alarms, etc.

Therefore, this improvement minimizes the number of Database operations when IoT Hub stores the data. For example, “temperature” and “humidity” would be stored as separate rows in SQL or NoSQL databases in order to efficiently aggregate this data for visualization. Since there is no need to aggregate JSON data, we can store all the content as one row instead of separate rows for each configuration item. In some of our environments, it is possible to decrease the number of database operations more than 10 times by aggregating multiple parameters within one JSON.

Learn more about JSON value support with the video.

RPC API

Server-side RPC

In order to subscribe to RPC commands from the server, send GET request with optional “timeout” request parameter to the following URL:

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http(s)://host:port/api/v1/$ACCESS_TOKEN/rpc

Once subscribed, a client may receive rpc request or a timeout message if there are no requests to a particular device. An example of RPC request body is shown below:

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{
  "id": "1",
  "method": "setGpio",
  "params": {
    "pin": "23",
    "value": 1
  }
}

where

• id - request id, integer request identifier
• method - RPC method name, string
• params - RPC method params, custom json object

and can reply to them using POST request to the following URL:

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http://host:port/api/v1/$ACCESS_TOKEN/rpc/{$id}

where $id is an integer request identifier.

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# for IoT Hub

# Send HTTP attributes request
curl -v -X GET https://iothub.magenta.at/api/v1/$ACCESS_TOKEN/rpc?timeout=20000

# for local IoT Hub

# Send rpc request with 20 seconds timeout
curl -v -X GET http://localhost:8080/api/v1/$ACCESS_TOKEN/rpc?timeout=20000

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# Publish response to RPC request
curl -v -X POST -d @rpc-response.json http://localhost:8080/api/v1/$ACCESS_TOKEN/rpc/1 --header "Content-Type:application/json"

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{"result":"ok"}

Client-side RPC

In order to send RPC commands to the server, send POST request to the following URL:

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http://host:port/api/v1/$ACCESS_TOKEN/rpc

Both request and response body should be valid JSON documents. The content of the documents is specific to the rule node that will handle your request.

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# for IoT Hub

# Send HTTP attributes request
curl -X POST -d @rpc-client-request.json https://iothub.magenta.at/api/v1/$ACCESS_TOKEN/rpc --header "Content-Type:application/json"

# for local IoT Hub

# Post client-side rpc request
curl -X POST -d @rpc-client-request.json http://localhost:8080/api/v1/$ACCESS_TOKEN/rpc --header "Content-Type:application/json"

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{"method": "getTime", "params":{}}

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{"time":"2016 11 21 12:54:44.287"}

Claiming devices

Please see the corresponding article to get more information about the Claiming devices feature.

In order to initiate claiming device, send POST request to the following URL:

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http(s)://host:port/api/v1/$ACCESS_TOKEN/claim

The supported data format is:

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{"secretKey":"value", "durationMs":60000}

Please note that the above fields are optional. In case the secretKey is not specified, the empty string as a default value is used. In case the durationMs is not specified, the system parameter device.claim.duration is used (in the file /etc/thingsboard/conf/thingsboard.yml).

Device provisioning

Please see the corresponding article to get more information about the Device provisioning feature.

In order to initiate device provisioning, send POST request to the following URL:

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http(s)://host:port/api/v1/provision

The supported data format is:

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{
  "deviceName": "DEVICE_NAME",
  "provisionDeviceKey": "u7piawkboq8v32dmcmpp",
  "provisionDeviceSecret": "jpmwdn8ptlswmf4m29bw"
}

Firmware API

When IoT Hub initiates the firmware update over HTTP it sets the fw_title, fw_version, fw_checksum, fw_checksum_algorithm shared attributes. To receive the shared attribute updates, the device has to GET request

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http(s)://host/api/v1/${access_token}/firmware?title=${title}&version=${version}

Where
host - your localhost, or the platform address;
${access_token} - the device access token;
${title} - the firmware title;
${version} - the version of the target firmware.

Protocol customization

HTTP transport can be fully customized for specific use-case by changing the corresponding module.

Next steps

• Getting started guides - These guides provide quick overview of main IoT Hub features. Designed to be completed in 15-30 minutes.

• Data visualization - These guides contain instructions how to configure complex IoT Hub dashboards.

• Data processing & actions - Learn how to use IoT Hub Rule Engine.

• IoT Data analytics - Learn how to use rule engine to perform basic analytics tasks.

• Hardware samples - Learn how to connect various hardware platforms to IoT Hub.

• Advanced features - Learn about advanced IoT Hub features.