HTTP Device API Reference¶

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.

Tempus Cloud 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, Tempus Cloud supports key-value content in JSON. Key is always a string, while value can be either string, boolean, double or long. Using custom binary format or some serialization framework is also possible. See protocol customization for more details. For example:

{"stringKey":"value1", "booleanKey":true, "doubleKey":42.0, "longKey":73}

Telemetry upload API¶

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

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

The simplest supported data formats are:

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

or

[{"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:

{"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’

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

{"key1":"value1", "key2":true, "key3": 3.0, "key4": 4}

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

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

Attributes API¶

Tempus Cloud 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 Tempus Cloud server node, send POST request to the following URL:

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

# Publish client-side attributes update
curl -v -X POST -d @new-attributes-values.json http://localhost:8080/api/v1/$ACCESS_TOKEN/attributes --header "Content-Type:application/json"

{"attribute1":"value1", "attribute2":true, "attribute3":42.0, "attribute4":73}

Request attribute values from the server¶

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

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

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

{"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.

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:

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:

{
    "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:

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

where $id is an integer request identifier.

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

# 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"

{"result":"ok"}

Client-side RPC¶

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

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

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

# 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"

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

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

Protocol customization¶

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

Device Telemetry Data Download¶

Time Series Data¶

Device Time Series data can be downloaded in CSV format between two timestamp values. The API can be invoked as below except that values in brackets needs to be replaced with actual values(device id, start timestamp, end timestamp).Authorization header values also need to be provided in headers.

http://host:port/api/download/deviceSeriesData?deviceId=<Device_Id>&type=ts&startValue<Start_Timestamp_Long_Value>&endValue<End_Timestamp_Long_Value>

Depth Series Data¶

Device Depth Series data can be downloaded in CSV format between two depth values. The API can be invoked as below except that values in brackets needs to be replaced with actual values(device id, start depth, end depth).Authorization header values also need to be provided in headers.

http://host:port/api/download/deviceSeriesData?deviceId=<Device_Id>&type=ds&startValue<Start_Depth_Double_Value>&endValue<End_Depth_Double_Value>

Attributes Data¶

Device Attributes data can be downloaded in CSV format. The API can be invoked as below except that value in bracket needs to be replaced with actual value(device id).Authorization header values also need to be provided in headers.

http://host:port/api/download/deviceAttributesData?deviceId=<Device_Id>