Deliver a Message to a Device

Function

This API is used by an application to deliver a message to a device. After an application delivers a message to the platform, the platform returns a response to the application and then sends the message to the device. The response returned by the platform may not be the device receiving result. Call the API Pushing a Device Message Status Change Notification for the platform to push the device receiving result to the application. Notes:

This API is only used to deliver messages to MQTT devices.
This API supports message delivery to a single device. For details about how to deliver messages to multiple devices, see Creating a Batch Task.

Debugging

You can debug this API through automatic authentication in API Explorer or use the SDK sample code generated by API Explorer.

URI

POST /v5/iot/{project_id}/devices/{device_id}/messages

**Table 1** Path Parameters
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: ID of the device to which the message is delivered. The ID is unique and is allocated by the platform during device registration. Value: The value can contain a maximum of 128 characters. Only letters, digits, underscores (_), and hyphens (-) are allowed.

Request Parameters

**Table 2** Request header 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. In the returned response header, X-Subject-Token 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.

**Table 3** Request body parameters
Parameter	Mandatory	Type	Description
message_id	No	String	Parameter description: message ID, which is user-defined (UUID is recommended). The ID must be unique under a device. Otherwise, an error is returned. Value: The value can contain a maximum of 128 characters. Only letters, digits, underscores (_), and hyphens (-) are allowed. Maximum: 128
name	No	String	Parameter description: message name. Value: The value can contain a maximum of 128 characters. Only letters, digits, and special characters (_?'#().,&%@!-) are allowed. Maximum: 128
message	Yes	Object	Parameter description: message content. String and JSON formats are supported.
properties	No	PropertiesDTO object	Parameter description: property parameter of the message delivered to the device.
encoding	No	String	Parameter description: encoding format for the message content. The default value is none. Options: none base64 Default: none
payload_format	No	String	Parameter description: valid payload format. This parameter is valid when the encoding format for the message content is none. The default value is standard, indicating that the message content is encapsulated in the standard format. Options: standard raw: The message content is directly delivered as the payload. Default: standard
topic	No	String	Parameter description: (optional) suffix of the custom topic through which the message is delivered to the device. This parameter is applicable only to MQTT devices. You can only enter topics configured on the tenant product page. Otherwise, the verification will fail. The prefix that the platform adds to a message topic is $oc/devices/{device_id}/user/. You can add a part to the prefix. For example, if you add messageDown to the prefix, the topic is $oc/devices/{device_id}/user/messageDown. Replace device_id with the actual gateway ID of the device. If you specify the topic, messages are delivered to the device through this topic. If you do not specify the topic, messages are delivered to the device through the default topic. The default topic is $oc/devices/{device_id}/sys/messages/down. Either this parameter or the topic_full_name parameter can be specified. Maximum: 128
topic_full_name	No	String	Parameter description: (optional) name of the topic through which the message is delivered to the device. You can specify a custom topic. The platform does not check whether the topic is defined on the platform and transparently transmits the topic to the device. The device needs to subscribe to the specified topic first. Either this field or the topic parameter can be specified. Maximum: 128
ttl	No	Integer	Parameter description: aging time of the caches of delivered messages on the platform, in minutes. The default value is 1440. The value of ttl must be a multiple of 5, that is, the granularity is 5 minutes. If this parameter is set to 0, messages are not cached. The maximum cache duration is 1,440 minutes. For longer cache duration, you need to submit a request in advance, or the delivery will fail. Minimum: 0 Default: 1440

**Table 4** PropertiesDTO
Parameter	Mandatory	Type	Description
correlation_data	No	String	Parameter description: data in the request and response modes of MQTT 5.0. This parameter is optional. You can use this parameter to configure data in the request and response modes of MQTT. Value: The value can contain a maximum of 128 characters. Only letters, digits, underscores (_), and hyphens (-) are allowed.
response_topic	No	String	Parameter description: response topic in the request and response modes of MQTT 5.0. This parameter is optional. You can use this parameter to configure the response topic in the request and response modes of MQTT. Value: The value can contain a maximum of 128 characters. Only letters, digits, and special characters (_-?=$#+/) are allowed. Maximum: 128
user_properties	No	Array of UserPropDTO objects	Parameter description: custom property. This parameter is optional. You can use this parameter to configure custom properties. A maximum of 20 customized attributes can be configured.

**Table 5** UserPropDTO
Parameter	Mandatory	Type	Description
prop_key	No	String	Parameter description: key of the custom property. Value: The value can contain a maximum of 128 characters. Only letters, digits, underscores (_), and hyphens (-) are allowed.
prop_value	No	String	Parameter description: value of the custom property. Value: The value can contain a maximum of 128 characters. Only letters, digits, underscores (_), and question marks (?) are allowed. '#().,& %@!-.

Response Parameters

Status code: 201

**Table 6** Response body parameters
Parameter	Type	Description
message_id	String	Message ID, which is specified by you (UUID is recommended). The message ID must be unique under a device. If the ID is not specified, the platform automatically generates one.
result	MessageResult object	Result of delivering the message. The value is in JSON format.

**Table 7** MessageResult
Parameter	Type	Description
status	String	Message status, including PENDING, DELIVERED, FAILED, and TIMEOUT. If the device is offline, the platform caches the message and returns PENDING. The platform delivers the message after the device reports data. If the device is online, the platform directly delivers the message. If the message is successfully delivered, the platform returns DELIVERED. If the message fails to be delivered, the platform returns FAILED. If the message is not delivered to the device within the default time (one day), the platform sets the message status to TIMEOUT. In addition, an application can subscribe to the message execution result. The platform pushes the result to the application.
created_time	String	UTC time when the message was created. The value is in the format of yyyyMMdd'T'HHmmss'Z'.
finished_time	String	UTC time when the message was delivered to the device, failed to be delivered, or timed out. The value is in the format of yyyyMMdd'T'HHmmss'Z'.

Example Requests

Creates a message and delivers it through the default topic of the platform.

POST https://{endpoint}/v5/iot/{project_id}/devices/{device_id}/messages

{
  "message_id" : "99b32da9-cd17-4cdf-a286-f6e849cbc364",
  "name" : "messageName",
  "message" : "HelloWorld"
}

Creates a message and delivers it through a custom topic on the platform.

POST https://{endpoint}/v5/iot/{project_id}/devices/{device_id}/messages

{
  "message_id" : "99b32da9-cd17-4cdf-a286-f6e849cbc364",
  "name" : "messageName",
  "message" : "HelloWorld",
  "topic" : "testTopic"
}

Creates a message and delivers it through a custom topic.

POST https://{endpoint}/v5/iot/{project_id}/devices/{device_id}/messages

{
  "message_id" : "99b32da9-cd17-4cdf-a286-f6e849cbc364",
  "name" : "messageName",
  "message" : "HelloWorld",
  "topic_full_name" : "/test/customTopic/testTopic"
}

Example Responses

Status code: 201

Created

{
  "message_id" : "b1224afb-e9f0-4916-8220-b6bab568e888",
  "result" : {
    "status" : "PENDING",
    "created_time" : "20151212T121212Z",
    "finished_time" : "20151212T121213Z"
  }
}