Platform Delivering a Command
Function
This API is used by the platform to deliver a command to a device. After the platform delivers a command, the device needs to return the command execution result to the platform in a timely manner. Otherwise, the platform considers that the command execution has timed out. For differences between command delivery and message delivery, see Message Communications.
It is not suitable to report data in JSON format for devices with low configuration and limited resources or with limits on bandwidth usage. In this case, devices can transparently transmit the original binary data to the platform, but a codec is required to convert binary data to JSON format. For details about how to develop codecs, see Developing a Codec.
Topic
Downstream: $oc/devices/{device_id}/sys/commands/request_id={request_id}
Upstream: $oc/devices/{device_id}/sys/commands/response/request_id={request_id}
- {request_id} is used to uniquely identify a request. If a device receives a downstream request with a topic carrying a request ID, the request ID must be included in the topic of the upstream response returned by the device.
- When an application delivers a device command through the platform, the platform generates a unique ID (command_id) to identify the command and returns the ID to the application. In addition, the ID is sent to the device through requst_id in the downstream topic of the device command.
- The device cannot detect the request_id in advance. When a device subscribes to a topic that ends with request_id={request_id}, the number sign (#) can be used to replaced request_id={request_id}, for example, $oc/devices/{device_id}/sys/commands/#.
Downstream Request Parameters
Parameter |
Mandatory or Optional |
Type |
Description |
---|---|---|---|
object_device_id |
Optional |
String |
|
service_id |
Optional |
String |
Device service ID, which is defined in the product model associated with the device. |
command_name |
Optional |
String |
Device command name, which is defined in the product model associated with the device. |
paras |
Mandatory |
Object |
Command execution parameters, which are defined in the product model associated with the device. |
Upstream Response Parameters
Responses are in JSON format.
Parameter |
Mandatory or Optional |
Type |
Description |
---|---|---|---|
result_code |
Optional |
Integer |
Command execution result. 0 indicates a successful execution, whereas other values indicate an execution failure. If this parameter is not specified, the default value 0 is used. |
response_name |
Optional |
String |
Response name of the command. |
paras |
Optional |
Object |
Indicates the response parameters, which are defined in the product model associated with the device. |
Example Downstream Request
Topic: $oc/devices/{device_id}/sys/commands/request_id={request_id} Data format: { "object_device_id": "{object_device_id}", "command_name": "ON_OFF", "service_id": "WaterMeter", "paras": { "value": "1" } }
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