Creating a Device Command
Typical Scenario
The device's product model defines commands that the platform can deliver to a device. When an application needs to configure or modify the service properties of a device, the application can call this API to deliver commands to the device.
The platform provides two command delivery modes:
- Immediate delivery: The platform delivers commands to devices immediately after receiving the commands. This ensures real-time performance but does not ensure serialization.
- Pending delivery: After receiving commands, the platform caches the commands. When the devices are reachable, the platform delivers the commands in sequence. Specifically, the platform delivers the latter command only after receiving a response of the previous command (which is the ACK automatically replied by the module) to ensure serialization instead of real-time performance.
This API applies to devices that use LWM2M over CoAP, for example, NB-IoT devices.
API Function
This API is used by applications to deliver commands to devices that use LWM2M over CoAP. Immediate delivery and pending delivery are supported on the platform.
API Description
1 | PostDeviceCommandOutDTO2 postDeviceCommand(PostDeviceCommandInDTO2 pdcInDTO, String appId, String accessToken) throws NorthApiException
|
Parameter Description
| Parameter | Mandatory or Optional | Type | Location | Description |
|---|---|---|---|---|
| pdcInDTO | Mandatory | PostDeviceCommandInDTO2 structure | body | For details, see PostDeviceCommandInDTO2 structure. |
| appId | Mandatory | String | query | If the device belongs to the current application, set this parameter to null. Otherwise, set this parameter to the ID of the authorized application. |
| accessToken | Mandatory | String | header | If the Periodically Refreshing a Token API is called, set this parameter to null. Otherwise, set this parameter to the accessToken obtained by the Authentication API. |
PostDeviceCommandInDTO2 structure
| Parameter | Mandatory or Optional | Type | Location | Description |
|---|---|---|---|---|
| deviceId | Mandatory | String(64) | body | Uniquely identifies the device to which the command is delivered. |
| command | Mandatory | CommandDTOV4 | body | Indicates information about the delivered command. For details, see CommandDTOV4 structure. |
| callbackUrl | Optional | String(1024) | body | Indicates the URL for receiving command status change notifications. When the command status changes, such as execution failure, execution success, timeout, sending, or sent, the application is notified. |
| expireTime | Optional | Integer(>=0) | body | Indicates the command expiration time, in seconds. The command will not be delivered after the specified time elapses. If this parameter is not specified, the default validity period is 48 hours (86400 seconds x 2). If this parameter is set to 0, the platform will deliver the command to the specific device immediately regardless of the command mode set on the platform (if the device is sleeping or the link has aged, the device cannot receive the command, the platform cannot receive any response from the device, and the command times out in the end). |
| maxRetransmit | Optional | Integer(0-3) | body | Indicates the maximum number of times the command can be retransmitted. |
| Parameter | Mandatory or Optional | Type | Location | Description |
|---|---|---|---|---|
| serviceId | Mandatory | String(1-64) | body | Identifies the service corresponding to the command. The value of this parameter must be the same as serviceId defined in the product model. |
| method | Mandatory | String(1-128) | body | Indicates the command name. The value of this parameter must be the same as the command name defined in the product model. |
| paras | Mandatory | ObjectNode | body | Indicates a command parameter in the jsonString format. The value consists of key-value pairs. Each key is the paraName parameter in commands in the product model. The specific format depends on the application and device. If no parameter is defined in the command in the product model, left it blank, that is, "paras": {}. |
Response Parameters
PostDeviceCommandOutDTO2 structure
| Parameter | Type | Description |
|---|---|---|
| commandId | String(1-64) | Identifies a device command. |
| appId | String(1-64) | Uniquely identifies an application. This parameter is used to identify an application that can call open APIs provided by the platform. |
| deviceId | String(1-64) | Uniquely identifies the device to which the command is delivered. |
| command | CommandDTOV4 | Indicates information about the delivered command. For details, see CommandDTOV4 structure. |
| callbackUrl | String(1024) | Indicates the URL for receiving command status change notifications. When the command status changes, such as execution failure, execution success, timeout, sending, or sent, the application is notified. |
| expireTime | Integer(>=0) | Indicates the command expiration time, in units of seconds. The command will not be delivered after the specified time elapses. The default validity period is 48 hours (86400 seconds x 2). |
| status | String | Indicates the status of the command.
|
| creationTime | String(20) | Indicates the time when the command is created. |
| executeTime | String(20) | Indicates the time when the command is executed. |
| platformIssuedTime | String(20) | Indicates the time when the platform sends the command. |
| deliveredTime | String(20) | Indicates the time when the command is delivered. |
| issuedTimes | Integer(>=0) | Indicates the number of times the platform delivers the command. |
| maxRetransmit | Integer(0-3) | Indicates the maximum number of times the command can be retransmitted. |
Error Codes
| HTTP Status Code | Error Code | Error Description | Remarks |
|---|---|---|---|
| 200 | 100203 | The application does not exist. | The application does not exist. Recommended handling:
|
| 200 | 100217 | The application has not been authorized. | The application has not been authorized. Recommended handling: In scenarios where applications are not authorized, ensure that request parameter appId is null. |
| 200 | 100418 | The device data does not exist. | The device data does not exist. Recommended handling:
|
| 200 | 100428 | The device is not online. | The device is not online. Recommended handling: Check whether the connection between the device and the IoT platform is normal. |
| 200 | 100431 | The service type does not exist. | The service type does not exist. Recommended handling:
|
| 400 | 100022 | An input parameter is invalid. | An input parameter is invalid. Recommended handling: Check whether parameters carried in the API call request are valid. |
| 400 | 100223 | The number of commands has reached the upper limit. | The number of cached commands reaches the limit. The number of commands in the PENDING state does not exceed the limit. The default value is 20. Recommended handling: If the commands cached on the IoT platform need to be executed, enable the device to report data to trigger delivery of the cache commands. If a command cached on the IoT platform does not need to be executed, call the API used for modifying device commands V4 to change the state of the command from PENDING to CANCELED. |
| 403 | 100217 | The application has not been authorized. | The application has not been authorized. Recommended handling: In scenarios where applications are not authorized, ensure that request parameter appId is null. |
| 403 | 100612 | The device is a zombie device. | The device is a zombie device. (The interval between the current system time and the time when the device went online exceeds the threshold. The default value is seven days.) Recommended handling: Run the command again after the device goes online. |
| 403 | 1010009 | The application calls the API at a frequency that exceeds the flow control threshold. | The application calls the API at a frequency that exceeds the flow control threshold (100 calls per minute by default). Recommended handling: Contact IoT platform maintenance personnel to adjust the flow control threshold or control the API call frequency. |
| 403 | 1010005 | Invalid access token or application ID. | The access token is invalid. Recommended handling: Check whether accessToken carried in the API request is correct. |
| 500 | 100001 | Internal server error. | An internal server error occurs. Recommended handling: An internal error occurs on the IoT platform. Contact IoT platform maintenance personnel. |
| 500 | 100023 | The data in the database is abnormal. | The database is abnormal. Recommended handling: An internal error occurs on the IoT platform. Contact IoT platform maintenance personnel. |
| 500 | 100220 | Failed to obtain the AppKey from the message header. | Failed to obtain the appKey. Recommended handling: Check whether appId is carried in the API request header. |
| 500 | 101016 | Failed to obtain the IoTWS address. | Failed to obtain the IoTWS address. Recommended handling: An internal error occurs on the IoT platform. Contact IoT platform maintenance personnel. |
| 500 | 101017 | Failed to obtain a new callback URL from OSS. | Obtaining a new callback URL from the OSS fails. Recommended handling: An internal error occurs on the IoT platform. Contact IoT platform maintenance personnel. |
| 503 | 100501 | Congestion occurs, and the current network is under flow control. | Congestion occurs. The current network is under flow control. Recommended handling: Try again later. |
Last Article: Command Delivery
Next Article: Querying Device Commands
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