Send the User a Progressive Response

Your skill can send progressive responses to keep the user engaged while your skill prepares a full response to the user's request. A progressive response is interstitial SSML content (including text-to-speech and short audio) that Alexa plays while waiting for your full skill response.

To send a progressive response, call the Progressive Response API and send a directive with the interstitial content.

• When to Send Progressive Responses
• Steps to Send a Progressive Response
• Use Audio within a Progressive Response
• Get the Required Data for the Progressive Response API
  • Obtain the API Access Token
  • Obtain the Request Identifier
• API Endpoint and Geographic Location of the Skill
• Send a Directive
  • Directive Request
    • Request Headers
    • Request Body
  • Directive Response
    • Possible Responses
• Related Topics

When to Send Progressive Responses

You can use progressive responses to:

• Send text-to-speech confirmations that your skill has received the request and is processing an answer.
• Play short soundmarks associated with your skill.
• Provide other engaging content to your users while waiting on the full response.

Progressive responses can also reduce the user's perception of latency in your skill's response.

For example, a skill to look up and book taxi rides might take a few seconds to access an external API to reserve a ride. Instead of remaining silent while the skill does this processing, you can return a message to let the user know that the skill is working on the request:

You can send progressive responses from the context of a current LaunchRequest or IntentRequest. You cannot send progressive responses from any other request types (such as AudioPlayer requests).

Steps to Send a Progressive Response

To send a progressive response, call the Progressive Response API and send a directive:

1. Get the required data from the incoming request (LaunchRequest or IntentRequest). You need the apiAccessToken and requestId to construct a valid Progressive Response API request.
2. Call the Progressive Response API and send a directive (such as VoicePlayer.Speak) with the content. The content must be valid SSML wrapped in <speak> tags.
3. Complete your normal skill processing.
4. Once the progressive response call completes, return your full skill response object. Note that you cannot send any more progressive responses after you return the response object.

Progressive responses are only played on the device if they arrive before the Alexa service receives the skill's full response object. For the best customer experience, your skill should wait until the progressive response call completes before you send the full response object. The Progressive Response API returns a 204 code once the progressive response is ready to be sent to the device.

Use Audio within a Progressive Response

You can embed short recorded audio within a progressive response with the SSML <audio> tag. The audio cannot be any longer than 30 seconds. Note that this is shorter than the normal audio allowed in the <audio> tag.

For optimal performance, we recommend that you host your MP3 files for SSML responses in close proximity to where your skill is hosted. For example, if the Lambda function for your skill is hosted in the US West (Oregon) region, you will get better performance if you upload your MP3s to a US West (Oregon) S3 bucket.

See <audio> for additional requirements around the MP3 files when using this tag.

Get the Required Data for the Progressive Response API

Every call to the Progressive Response API requires an apiAccessToken and the requestID for the specific request sent to your skill. You can obtain both of these from the request sent to your skill.

Obtain the API Access Token

Use the apiAccessToken provided in the context object. The token is included in all requests sent to your skill.

The context object is included in all requests. You can access the apiAccessToken in context.System.apiAccessToken. Include the complete value of this property in your call to the Progressive Response API.

{
  "version": "1.0",
  "session": {},
  "context": {
    "AudioPlayer": {},
    "System": {
      "application": {
        "applicationId": "amzn1.ask.skill.[unique-value-here]"
      },
      "user": {},
      "device": {},
      "apiEndpoint": "https://api.amazonalexa.com",
      "apiAccessToken": "AxThk..."
    }
  },
  "request": {}
}

In the above example, some objects and properties are removed for clarity.

Obtain the Request Identifier

The requestId identifies a specific request sent from Alexa to your skill. This value is included in all requests sent to your skill as part of the request object, such as LaunchRequest or IntentRequest. You can get the requestId from request.requestId.

{
  "version": "1.0",
  "session": {},
  "context": {},
  "request": {
    "type": "LaunchRequest",
    "requestId": "amzn1.echo-api.request.xxxxxxx",
    "timestamp": "2015-05-13T12:34:56Z",
    "locale": "en-US"
  }
}

In the above example, some objects and properties are removed for clarity.

Pass the entire value of the request.requestId property to the Progressive Response API.

API Endpoint and Geographic Location of the Skill

The endpoint for the Progressive Response API varies depending on the geographic location of your skill. You can get the correct base URL to use from the apiEndpoint value in the System object. That is, the API endpoint is context.System.apiEndpoint.

{
  "version": "1.0",
  "session": {},
  "context": {
    "System": {
      "application": {
        "applicationId": "amzn1.ask.skill.<skill-id>"
      },
      "user": {},
      "apiAccessToken": "AxThk...",
      "apiEndpoint": "https://api.amazonalexa.com"
    }
  },
  "request": {}
}

The examples on this page use the US endpoint (https://api.amazonalexa.com/).

For details about configuring your skill for multiple languages, see Develop Skills in Multiple Languages.

Send a Directive

This API call sends the specified directive to Alexa. Currently, the only supported directive is VoicePlayer.Speak. This instructs Alexa to speak the provided speech. You must wrap the speech in <speak> tags. You can use SSML tags within the speech as needed.

Your skill can send a maximum of five directive requests for a single user request. Any calls beyond this limit are rejected. Each directive request must be sent in a separate API call.

Endpoint: /v1/directives

Method: POST

Directive Request

POST https://api.amazonalexa.com/v1/directives HTTP/1.1
Authorization: Bearer AxThk...
Content-Type: application/json

{ 
  "header":{ 
    "requestId":"amzn1.echo-api.request.xxxxxxx"
  },
  "directive":{ 
    "type":"VoicePlayer.Speak",
    "speech":"<speak>This text is spoken while your skill processes the full response.</speak>"
  }
}

Note that the actual token in the Authorization header would be much longer than shown in this example.

Request Headers

Request Body

Provide the request body in a JSON object:

{ 
  "header":{ 
    "requestId":"amzn1.echo-api.request.xxxxxxx"
  },
  "directive":{ 
    "type":"VoicePlayer.Speak",
    "speech":"<speak>This text is spoken while your skill processes the full response.</speak>"
  }
}

Directive Response

If Alexa is able to process and speak the text provided in your directive request, the service returns an HTTP 204 code. The response does not include any additional data. Any other status code indicates an error that prevented Alexa from speaking the text.

If a properly-formed directive request fails, you can safely resend it to retry. Alexa does not play the same content multiple times.

Possible Responses

The directive request can return the following codes:

Related Topics

• Handling Requests Sent by Alexa
• Request and Response JSON Reference
• Request Types Reference (LaunchRequest, IntentRequest, SessionEndedRequest)
• Steps to Build a Custom Skill
• Progressive Response API example (GitHub)
• Directive service in the Alexa Skills Kit SDK for Node.js (GitHub)

Last updated: Mar 30, 2022