Request Syntax URI Request Parameters Request Body Response Syntax Response Elements Errors See Also

SendDirectMessage

Sends an MQTT message directly to a specific client identified by its client ID.

SendDirectMessage targets a single client ID. The receiving client does not need to subscribe to the topic, but the receiver's policy must allow iot:Receive on the specified topic.

Requires permission to access the SendDirectMessage action.

For more information about messaging costs, see AWS IoT Core pricing.

Request Syntax


POST /connections/clientId/messages?confirmation=confirmation&contentType=contentType&responseTopic=responseTopic&timeout=timeout&topic=topic HTTP/1.1
x-amz-mqtt5-user-properties: userProperties
x-amz-mqtt5-payload-format-indicator: payloadFormatIndicator
x-amz-mqtt5-correlation-data: correlationData

payload

URI Request Parameters

The request uses the following URI parameters.

clientId

The unique identifier of the MQTT client to send the message to.

Client IDs must not exceed 128 characters and can't start with a dollar sign ($). MQTT client IDs must be URL encoded (percent-encoded) when they contain characters that are not valid in HTTP requests, such as spaces, forward slashes (/), and UTF-8 characters. For more information, see AWS IoT Core message broker and protocol limits and quotas.

Length Constraints: Minimum length of 1. Maximum length of 128.

Pattern: ^[^$].*

Required: Yes

confirmation

A Boolean value that specifies whether to wait for delivery confirmation from the receiving client.

When set to true, the API delivers the message at QoS 1 and waits for the client to send a delivery confirmation (PUBACK) before returning a successful response. If delivery confirmation is not received within the specified timeout period, the API returns HTTP 504.

When set to false, the API delivers the message at QoS 0 and returns after AWS IoT Core attempts to deliver the message.

Valid values: true | false

Default value: false

contentType

The MQTT5 content type property forwarded to the receiving client (for example, application/json).

correlationData

The base64-encoded binary data used by the sender of the request message to identify which request the response message is for when it's received. correlationData is an HTTP header value in the API.

payloadFormatIndicator

An Enum string value that indicates whether the payload is formatted as UTF-8. payloadFormatIndicator is an HTTP header value in the API.

Valid Values: UNSPECIFIED_BYTES | UTF8_DATA

responseTopic

A UTF-8 encoded string that's used as the topic name for a response message. The response topic describes the topic which the receiver should publish to as part of the request-response flow. The topic must not contain wildcard characters. For more information, see AWS IoT Core message broker and protocol limits and quotas.

timeout

An integer that represents the maximum time, in seconds, to wait for a delivery confirmation (PUBACK) from the receiving client after the message has been delivered. This parameter is only used when confirmation is set to true. If confirmation is false, this parameter is ignored.

The total API response time may be higher than this value due to internal processing. Set your HTTP client timeout to a value greater than this parameter.

Valid range: 1 to 15 seconds.

Default value: 5 seconds.

topic

The topic of the outbound MQTT Publish message to the receiving client. For more information, see AWS IoT Core message broker and protocol limits and quotas.

Required: Yes

userProperties

A JSON string that contains an array of JSON objects. If you don't use AWS SDK or AWS CLI, you must encode the JSON string to base64 format before adding it to the HTTP header. userProperties is an HTTP header value in the API.

For MQTT 3.1.1 clients, user properties are silently dropped.

The following example userProperties parameter is a JSON string which represents two User Properties. Note that it needs to be base64-encoded:

[{"deviceName": "alpha"}, {"deviceCnt": "45"}]

Request Body

The request accepts the following binary data.

payload: The message body. MQTT accepts text, binary, and empty (null) message payloads.

Response Syntax


HTTP/1.1 200
Content-type: application/json

{
   "message": "string",
   "traceId": "string"
}

Response Elements

If the action is successful, the service sends back an HTTP 200 response.

The following data is returned in JSON format by the service.

message

The status message indicating the result of the operation.

Type: String

traceId

A unique identifier for the request. Include this value when contacting AWS Support for troubleshooting.

Type: String

Errors

ForbiddenException

The caller isn't authorized to make the request.

HTTP Status Code: 403

GatewayTimeoutException

The delivery confirmation was not received from the client within the specified timeout period.

message: The message for the exception.

HTTP Status Code: 504

InternalFailureException

An unexpected error has occurred.

message: The message for the exception.

HTTP Status Code: 500

InvalidRequestException

The request is not valid.

message: The message for the exception.

HTTP Status Code: 400

RequestEntityTooLargeException

The payload exceeds the maximum size allowed.

message: The message for the exception.

HTTP Status Code: 413

ResourceNotFoundException

The specified resource does not exist.

message: The message for the exception.

HTTP Status Code: 404

ThrottlingException

The rate exceeds the limit.

message: The message for the exception.

HTTP Status Code: 429

UnauthorizedException

You are not authorized to perform this operation.

message: The message for the exception.

HTTP Status Code: 401