Query a Device Shadow
Function
This API is used by an application to query the device shadow of a specific device, including the desired device properties (in the desired section) and the latest properties reported by the device (in the reported section).
Introduction: A device shadow is a JSON file used to store and obtain device status.
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Each device has only one device shadow, which is uniquely identified by the device ID.
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A device shadow stores the properties (status) reported by a device and the properties (status) expected by an application.
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You can obtain and set the device properties through the device shadow, regardless of whether the device is online.
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After a device goes online or reports data, if the reported properties are different from the desired ones, the desired properties are delivered to the device. The desired properties can be delivered only when they have been defined in the product model and method is specified as W.
Restrictions: Keys in the device shadow JSON file cannot contain periods (.), dollar signs ($), and the null character (hexadecimal ASCII code 00). Otherwise, the device shadow file cannot be updated.
Debugging
You can debug this API through automatic authentication in API Explorer or use the SDK sample code generated by API Explorer.
URI
GET /v5/iot/{project_id}/devices/{device_id}/shadow
Parameter |
Mandatory |
Type |
Description |
---|---|---|---|
project_id |
Yes |
String |
Parameter description: project ID. For details about how to obtain the project ID, see Obtaining a Project ID. |
device_id |
Yes |
String |
Parameter description: device ID, which uniquely identifies a device. The value of this parameter is specified during device registration or allocated by the platform. Value: The value can contain a maximum of 128 characters. Only letters, digits, underscores (_), and hyphens (-) are allowed. |
Request Parameters
Parameter |
Mandatory |
Type |
Description |
---|---|---|---|
X-Auth-Token |
No |
String |
Parameter description: user token. You can obtain the token by calling the IAM API Obtaining a User Token Through Password Authentication. X-Subject-Token in the response header returned by the API is the desired user token. For details about how to obtain the token, see Token Authentication. |
Instance-Id |
No |
String |
Parameter description: instance ID. Unique identifier of each instance in the physical multi-tenant scenario. Mandatory for professional editions and recommended in other cases. Log in to the IoTDA console and choose Overview in the navigation pane to view the instance ID. For details, see Viewing Instance Details. |
Response Parameters
Status code: 200
Parameter |
Type |
Description |
---|---|---|
device_id |
String |
Device ID, used to uniquely identify a device. The value of this parameter is specified during device registration or allocated by the platform. If the value is allocated by the platform, the value is in the format of [product_id]_[node_id]. |
shadow |
Array of DeviceShadowData objects |
Device shadow data structure. |
Parameter |
Type |
Description |
---|---|---|
service_id |
String |
Device service ID, which is defined in the product model associated with the device. Minimum: 1 Maximum: 256 |
desired |
DeviceShadowProperties object |
Latest desired properties delivered to the device. The data is JSON data and is in the format of key-value pairs. Each key is a parameter name of a property (property_name) in the product model. |
reported |
DeviceShadowProperties object |
Latest properties reported by the device. The data is JSON data and is in the format of key-value pairs. Each key is a parameter name of a property (property_name) in the product model. |
version |
Long |
Version of the device shadow. When this parameter is carried, the platform will check whether the value is the same as the current shadow version. The initial value is 0. |
Parameter |
Type |
Description |
---|---|---|
properties |
Object |
Properties stored in the device shadow. The data is JSON data and is in the format of key-value pairs. Each key is a parameter name of a property (property_name) in the product model. Only one-layer structure is supported, as shown in the example. Note: Keys in the JSON file cannot contain periods (.), dollar signs ($), and the null character (hexadecimal ASCII code 00). Keys that contain these special characters will cause device shadow update failures. |
event_time |
String |
Time when the event occurred. The value is in the format of yyyyMMdd'T'HHmmss'Z', for example, 20151212T121212Z. Maximum: 256 |
Example Requests
Query the device shadow of a specified device.
GET https://{endpoint}/v5/iot/{project_id}/devices/{device_id}/shadow
Example Responses
Status code: 200
OK
{ "device_id" : "40fe3542-f4cc-4b6a-98c3-61a49ba1acd4", "shadow" : [ { "service_id" : "WaterMeter", "desired" : { "properties" : { "temperature" : "60" }, "event_time" : "20151212T121212Z" }, "reported" : { "properties" : { "temperature" : "60" }, "event_time" : "20151212T121212Z" }, "version" : 1 } ] }
Status Codes
Status Code |
Description |
---|---|
200 |
OK |
400 |
Bad Request |
401 |
Unauthorized |
403 |
FORBIDDEN |
404 |
Not Found |
500 |
INTERNAL SERVER ERROR |
Error Codes
See Error Codes.
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