node package manager
It’s your turn. Help us improve JavaScript. Take the 2017 JavaScript Ecosystem Survey »

alexa-sdk

Alexa Skills Kit SDK for Node.js

Overview

Alexa SDK team is proud to present the new Alexa Node.js SDK -- the open-source Alexa Skill Development Kit built by developers for developers.

Creating an Alexa skill using the Alexa Skill Kit, Node.js and AWS Lambda has become one of the most popular ways we see skills created today. The event-driven, non-blocking I/O model of Node.js is well-suited for an Alexa skill and Node.js is one of the largest ecosystems of open source libraries in the world. Plus, AWS Lambda is free for the first one million calls per month, which is sufficient for most Alexa skill developers. Also, when using AWS Lambda you don't need to manage any SSL certificates since the Alexa Skills Kit is a trusted trigger.

Setting up an Alexa skill using AWS Lambda, Node.js and the Alexa Skills Kit has been a simple process. However, the actual amount of code you have to write has not. Alexa SDK team has now built an Alexa Skills Kit SDK specifically for Node.js that will help you avoid common hang-ups and focus on your skill's logic instead of boilerplate code.

With the new alexa-sdk, our goal is to help you build skills faster while allowing you to avoid unneeded complexity. Today, we are launching the SDK with the following capabilities:

  • Hosted as an NPM package allowing simple deployment to any Node.js environment
  • Ability to build Alexa responses using built-in events
  • Helper events for new sessions and unhandled events that can act as a 'catch-all' events
  • Helper functions to build state-machine based Intent handling
  • This makes it possible to define different event handlers based on the current state of the skill
  • Simple configuration to enable attribute persistence with DynamoDB
  • All speech output is automatically wrapped as SSML
  • Lambda event and context objects are fully available via this.event and this.context
  • Ability to override built-in functions giving you more flexibility on how you manage state or build responses. For example, saving state attributes to AWS S3.

Setup Guide

The alexa-sdk is immediately available on Github and can be deployed as a node package using the following command from your Node.js environment:

npm install --save alexa-sdk

Getting Started: Writing a Hello World Skill

Basic Project Structure

Your HelloWorld skill needs to have:

  • entry point to your skill where you'll import all packages needed for the skill, receive the events, set appId, set dynamoDB table, register handlers and so on;
  • handler functions which handle each request.

Set Entry Point

To do this within your own project simply create a file named index.js and add the following to it:

const Alexa = require('alexa-sdk');
 
exports.handler = function(event, context, callback) {
    const alexa = Alexa.handler(event, context, callback);
    alexa.appId = APP_ID // APP_ID is your skill id which can be found in the Amazon developer console where you create the skill.
    alexa.execute();
};

This will import alexa-sdk and set up an Alexa object for us to work with.

Implement Handler Functions

Next, we need to handle the events and intents for our skill. Alexa-sdk makes it simple to have a function fire an intent. You can implement the handers functions in index.js file just created or you can also write in separate files and import them later. For example, to create a handler for 'HelloWorldIntent', we can do it in two ways:

const handlers = {
    'HelloWorldIntent' : function() {
        //emit response directly
        this.emit(':tell', 'Hello World!');
    }
};

Or

const handlers = {
    'HelloWorldIntent' : function() {
        //build response first using responseBuilder and then emit
        this.response.speak('Hello World!');
        this.emit(':responseReady');
    }
};

Alexa-sdk follows a tell/ask response methodology for generating the outputSpeech response objects corresponding to speak/listen in responseBuilder.

this.emit(':tell', 'Hello World!'); 
this.emit(':ask', 'What would you like to do?', 'Please say that again?');

which is equivalent to:

this.response.speak('Hello World!');
this.emit(':responseReady');
 
this.response.speak('What would you like to do?')
            .listen('Please say that again?');
this.emit(':responseReady');

The difference between :ask/listen and :tell/speak is that after a :tell/speak action, the session is ended without waiting for the user to provide more input. We will compare the two ways using response or using responseBuilder to create the response object in next section.

The handlers can forward request to each other, making it possible to chain handlers together for better user flow. Here is an example where our LaunchRequest and IntentRequest(of HelloWorldIntent) both return the same 'Hello World' message.

const handlers = {
    'LaunchRequest': function () {
     this.emit('HelloWorldIntent');
    },
 
    'HelloWorldIntent': function () {
     this.emit(':tell', 'Hello World!');
    }
};

Once we have set up event handlers we need to register them using the registerHandlers function of the alexa object we just created. So in the index.js file we created, add the following:

const Alexa = require('alexa-sdk');
 
exports.handler = function(event, context, callback) {
    const alexa = Alexa.handler(event, context, callback);
    alexa.registerHandlers(handlers);
    alexa.execute();
};

You can also register multiple handler objects at once:

alexa.registerHandlers(handlers, handlers2, handlers3, ...);

Once you finish the above steps, your skill should work properly on the device.

Response vs ResponseBuilder

Currently, there are two ways to generate the response objects in Node.js SDK. The first way is using the syntax follows the format this.emit(:${action}, 'responseContent').
Here are full list examples for common skill responses below:

Response Syntax Description
this.emit(':tell',speechOutput); Tell with speechOutput
this.emit(':ask', speechOutput, repromptSpeech); Ask with speechOutput and repromptSpeech
this.emit(':tellWithCard', speechOutput, cardTitle, cardContent, imageObj); Tell with speechOutput and standard card
this.emit(':askWithCard', speechOutput, repromptSpeech, cardTitle, cardContent, imageObj); Ask with speechOutput, repromptSpeech and standard card
this.emit(':tellWithLinkAccountCard', speechOutput); Tell with linkAccount card, for more information, click here
this.emit(':askWithLinkAccountCard', speechOutput); Ask with linkAccount card, for more information, click here
this.emit(':tellWithPermissionCard', speechOutput, permissionArray); Tell with permission card, for more information, click here
this.emit(':askWithPermissionCard', speechOutput, repromptSpeech, permissionArray) Ask with permission card, for more information, click here
this.emit(':delegate', updatedIntent); Response with delegate directive in dialog model
this.emit(':elicitSlot', slotToElicit, speechOutput, repromptSpeech, updatedIntent); Response with elicitSlot directive in dialog model
this.emit(':elicitSlotWithCard', slotToElicit, speechOutput, repromptSpeech, cardTitle, cardContent, updatedIntent, imageObj); Response with card and elicitSlot directive in dialog model
this.emit(':confirmSlot', slotToConfirm, speechOutput, repromptSpeech, updatedIntent); Response with confirmSlot directive in dialog model
this.emit(':confirmSlotWithCard', slotToConfirm, speechOutput, repromptSpeech, cardTitle, cardContent, updatedIntent, imageObj); Response with card and confirmSlot directive in dialog model
this.emit(':confirmIntent', speechOutput, repromptSpeech, updatedIntent); Response with confirmIntent directive in dialog model
this.emit(':confirmIntentWithCard', speechOutput, repromptSpeech, cardTitle, cardContent, updatedIntent, imageObj); Reponse with card and confirmIntent directive in dialog model
this.emit(':responseReady'); Called after the response is built but before it is returned to the Alexa service. Calls : saveState. Can be overridden.
this.emit(':saveState', false); Handles saving the contents of this.attributes and the current handler state to DynamoDB and then sends the previously built response to the Alexa service. Override if you wish to use a different persistence provider. The second attribute is optional and can be set to 'true' to force saving.
this.emit(':saveStateError'); Called if there is an error while saving state. Override to handle any errors yourself.

If you want to manually create your own responses, you can use this.response to help. this.response contains a series of functions, that you can use to set the different properties of the response. This allows you to take advantage of the Alexa Skills Kit's built-in audio and video player support. Once you've set up your response, you can just call this.emit(':responseReady') to send your response to Alexa. The functions within this.response are also chainable, so you can use as many as you want in a row. Here is full list example of creating response using responseBuilder.

Response Syntax Description
this.response.speak(speechOutput); Set the first speech output to speechOutput
this.response.listen(repromptSpeech); Set the reprompt speech output to repromptSpeech, shouldEndSession to false. Unless this function is called, this.response will set shouldEndSession to true.
this.response.cardRenderer(cardTitle, cardContent, cardImage); Add a standard card with cardTitle, cardContent and cardImage in response
this.response.linkAccountCard(); Add a linkAccount card in response, for more information, click here
this.response.askForPermissionsConsentCard(permissions); Add a card to ask for perimission in response, for more information, click here
this.response.audioPlayer(directiveType, behavior, url, token, expectedPreviousToken, offsetInMilliseconds);(Deprecated) Add an AudioPlayer directive with provided parameters in response.
this.response.audioPlayerPlay(behavior, url, token, expectedPreviousToken, offsetInMilliseconds); Add an AudioPlayer directive using the provided parameters, and set AudioPlayer.Play as the directive type.
this.response.audioPlayerStop(); Add an AudioPlayer.Stop directive
this.response.audioPlayerClearQueue(clearBehavior); Add an AudioPlayer.ClearQueue directive and set the clear behaviour of the directive.
this.response.renderTemplate(template); Add a Display.RenderTemplate directive in response
this.response.hint(hintText, hintType); Add a Hint directive in response
this.response.playVideo(videoSource, metadata); Add a VideoApp.Play directive in response
this.response.shouldEndSession(bool); Set shouldEndSession manually

When you have finished set up your response, simply call this.emit(':responseReady') to send your response off. Below are two examples that build response with several response objects:

//Example 1
this.response.speak(speechOutput)
            .listen(repromptSpeech);
this.emit(':responseReady');
//Example 2
this.response.speak(speechOutput)
            .cardRenderer(cardTitle, cardContent, cardImage)
            .renderTemplate(template)
            .hint(hintText, hintType);
this.emit(':responseReady');

Since responseBuilder is more flexible to build rich response objects, we prefer using this method to build the response.

Tips

  • When any of the response events are emitted :ask, :tell, :askWithCard, etc. The lambda context.succeed() method is called if the developer doesn't pass in callback function, which immediately stops processing of any further background tasks. Any asynchronous jobs that are still incomplete will not be completed and any lines of code below the response emit statement will not be executed. This is not the case for non responding events like :saveState.
  • To "transfer" a request from one state handler to another which is called intent forwarding, this.handler.state needs to be set to the name of the target state. If the target state is "", then this.emit("TargetHandlerName") should be called. For any other states, this.emitWithState("TargetHandlerName") must be called instead.
  • The contents of the prompt and reprompt values get wrapped in SSML tags. This means that any special XML characters within the value need to be escape coded. For example, this.emit(":ask", "I like M&M's") will cause a failure because the & character needs to be encoded as &amp;. Other characters that need to be encoded include: < -> &lt;, and > -> &gt;.

Standard Request and Response

Alexa communicates with the skill service via a request-response mechanism using HTTP over SSL/TLS. When a user interacts with an Alexa skill, your service receives a POST request containing a JSON body. The request body contains the parameters necessary for the service to perform its logic and generate a JSON-formatted response. Since Node.js can handle JSON natively, Alexa Node.js SDK doesn't need to do JSON serialization and deserialization. Developers are only responsible for providing a proper response object in order for Alexa to respond to a customer request. The documentation on the JSON structure of the request body can be found here.

A SpeechletResponse may contain the following attributes:

  • OutputSpeech
  • Reprompt
  • Card
  • List of Directives
  • shouldEndSession

As an example, a simple response containing both speech and a card can be constructed as follows:

const speechOutput = 'Hello world!';
const repromptSpeech = 'Hello again!';
const cardTitle = 'Hello World Card';
const cardContent = 'This text will be displayed in the companion app card.';
const imageObj = {
    smallImageUrl: 'https://imgs.xkcd.com/comics/standards.png',
    largeImageUrl: 'https://imgs.xkcd.com/comics/standards.png'
};
this.response.speak(speechOutput)
            .listen(repromptSpeech)
            .cardRenderer(cardTitle, cardContent, imageObj);
this.emit(':responseReady');

Interfaces

AudioPlayer Interface

Developers can include the following directives in their skill responses (respectively)

  • PlayDirective
  • StopDirective
  • ClearQueueDirective

Here is an example of using PlayDirective to stream audio:

const handlers = {
    'LaunchRequest' : function() {
        const speechOutput = 'Hello world!';
        const behavior = 'REPLACE_ALL';
        const url = 'https://url/to/audiosource';
        const token = 'myMusic';
        const expectedPreviousToken = 'expectedPreviousStream';
        const offsetInMilliseconds = 10000;
        this.response.speak(speechOutput)
                    .audioPlayerPlay(behavior, url, token, expectedPreviousToken, offsetInMilliseconds);
        this.emit(':responseReady');
    }
};

In the above example, Alexa will speak the speechOutput first and then try to play audio.

When building skills that leverage the AudioPlayer interfaces, the playback requests will be send to notify the skill about changes to the playback state.You can implement handler functions for their respective events.

const handlers = {
    'AudioPlayer.PlaybackStarted' : function() {
     console.log('Alexa begins playing the audio stream');
    },
    'AudioPlayer.PlaybackFinished' : function() {
     console.log('The stream comes to an end');
    },
    'AudioPlayer.PlaybackStopped' : function() {
     console.log('Alexa stops playing the audio stream');
    },
    'AudioPlayer.PlaybackNearlyFinished' : function() {
     console.log('The currently playing stream is nearly complate and the device is ready to receive a new stream');
    },
    'AudioPlayer.PlaybackFailed' : function() {
     console.log('Alexa encounters an error when attempting to play a stream');
    }
};

Additional documentation about AudioPlayer interface can be found here.

Note: for specifications regarding the imgObj please see here

Dialog Interface

The Dialog interface provides directives for managing a multi-turn conversation between your skill and the user. You can use the directives to ask the user for the information you need to fulfill their request. See the Dialog Interface and Skill Editor documentation for more information on how to use dialog directives.

You can use this.event.request.dialogState to access current dialogState.

Delegate Directive

Sends Alexa a command to handle the next turn in the dialog with the user. You can use this directive if the skill has a dialog model and the current status of the dialog (dialogState) is either STARTED or IN_PROGRESS. You cannot emit this directive if the dialogState is COMPLETED.

You can use this.emit(':delegate') to send delegate directive response.

const handlers = {
    'BookFlightIntent': function () {
        if (this.event.request.dialogState === 'STARTED') {
            let updatedIntent = this.event.request.intent;
            // Pre-fill slots: update the intent object with slot values for which
            // you have defaults, then emit :delegate with this updated intent.
            updatedIntent.slots.SlotName.value = 'DefaultValue';
            this.emit(':delegate', updatedIntent);
        } else if (this.event.request.dialogState !== 'COMPLETED'){
            this.emit(':delegate');
        } else {
            // All the slots are filled (And confirmed if you choose to confirm slot/intent)
            handlePlanMyTripIntent();
        }
    }
};

Elicit Slot Directive

Sends Alexa a command to ask the user for the value of a specific slot. Specify the name of the slot to elicit in the slotToElicit. Provide a prompt to ask the user for the slot value in speechOutput.

You can use this.emit(':elicitSlot', slotToElicit, speechOutput, repromptSpeech, updatedIntent) or this.emit(':elicitSlotWithCard', slotToElicit, speechOutput, repromptSpeech, cardTitle, cardContent, updatedIntent, imageObj) to send elicit slot directive response.

When using this.emit(':elicitSlotWithCard', slotToElicit, speechOutput, repromptSpeech, cardTitle, cardContent, updatedIntent, imageObj), updatedIntent and imageObj are optional parameters. You can set them to null or not pass them.

const handlers = {
    'BookFlightIntent': function () {
        const intentObj = this.event.request.intent;
        if (!intentObj.slots.Source.value) {
            const slotToElicit = 'Source';
            const speechOutput = 'Where would you like to fly from?';
            const repromptSpeech = speechOutput;
            this.emit(':elicitSlot', slotToElicit, speechOutput, repromptSpeech);
        } else if (!intentObj.slots.Destination.value) {
            const slotToElicit = 'Destination';
            const speechOutput = 'Where would you like to fly to?';
            const repromptSpeech = speechOutput;
            const cardContent = 'What is the destination?';
            const cardTitle = 'Destination';
            const updatedIntent = intentObj;
            // An intent object representing the intent sent to your skill.
            // You can use this property set or change slot values and confirmation status if necessary.
            const imageObj = {
                smallImageUrl: 'https://imgs.xkcd.com/comics/standards.png',
                largeImageUrl: 'https://imgs.xkcd.com/comics/standards.png'
            };
            this.emit(':elicitSlotWithCard', slotToElicit, speechOutput, repromptSpeech, cardTitle, cardContent, updatedIntent, imageObj);
        } else {
            handlePlanMyTripIntentAllSlotsAreFilled();
        }
    }
};

Confirm Slot Directive

Sends Alexa a command to confirm the value of a specific slot before continuing with the dialog. Specify the name of the slot to confirm in the slotToConfirm. Provide a prompt to ask the user for confirmation in speechOutput.

You can use this.emit(':confirmSlot', slotToConfirm, speechOutput, repromptSpeech, updatedIntent) or this.emit(':confirmSlotWithCard', slotToConfirm, speechOutput, repromptSpeech, cardTitle, cardContent, updatedIntent, imageObj) to send confirm slot directive response.

When using this.emit(':confirmSlotWithCard', slotToConfirm, speechOutput, repromptSpeech, cardTitle, cardContent, updatedIntent, imageObj), updatedIntent and imageObj are optional parameters. You can set them to null or not pass them.

const handlers = {
    'BookFlightIntent': function () {
        const intentObj = this.event.request.intent;
        if (intentObj.slots.Source.confirmationStatus !== 'CONFIRMED') {
            if (intentObj.slots.Source.confirmationStatus !== 'DENIED') {
                // Slot value is not confirmed
                const slotToConfirm = 'Source';
                const speechOutput = 'You want to fly from ' + intentObj.slots.Source.value + ', is that correct?';
                const repromptSpeech = speechOutput;
                this.emit(':confirmSlot', slotToConfirm, speechOutput, repromptSpeech);
            } else {
                // Users denies the confirmation of slot value
                const slotToElicit = 'Source';
                const speechOutput = 'Okay, Where would you like to fly from?';
                this.emit(':elicitSlot', slotToElicit, speechOutput, speechOutput);
            }
        } else if (intentObj.slots.Destination.confirmationStatus !== 'CONFIRMED') {
            if (intentObj.slots.Destination.confirmationStatus !== 'DENIED') {
                const slotToConfirm = 'Destination';
                const speechOutput = 'You would like to fly to ' + intentObj.slots.Destination.value + ', is that correct?';
                const repromptSpeech = speechOutput;
                const cardContent = speechOutput;
                const cardTitle = 'Confirm Destination';
                this.emit(':confirmSlotWithCard', slotToConfirm, speechOutput, repromptSpeech, cardTitle, cardContent);
            } else {
                const slotToElicit = 'Destination';
                const speechOutput = 'Okay, Where would you like to fly to?';
                const repromptSpeech = speechOutput;
                this.emit(':elicitSlot', slotToElicit, speechOutput, repromptSpeech);
            }
        } else {
            handlePlanMyTripIntentAllSlotsAreConfirmed();
        }
    }
};

Confirm Intent Directive

Sends Alexa a command to confirm the all the information the user has provided for the intent before the skill takes action. Provide a prompt to ask the user for confirmation in speechOutput. Be sure to repeat back all the values the user needs to confirm in the prompt.

You can use this.emit(':confirmIntent', speechOutput, repromptSpeech, updatedIntent) or this.emit(':confirmIntentWithCard', speechOutput, repromptSpeech, cardTitle, cardContent, updatedIntent, imageObj) to send confirm intent directive response.

When using this.emit(':confirmIntentWithCard', speechOutput, repromptSpeech, cardTitle, cardContent, updatedIntent, imageObj), updatedIntent and imageObj are optional parameters. You can set them to null or not pass them.

const handlers = {
    'BookFlightIntent': function () {
        const intentObj = this.event.request.intent;
        if (intentObj.confirmationStatus !== 'CONFIRMED') {
            if (intentObj.confirmationStatus !== 'DENIED') {
                // Intent is not confirmed
                const speechOutput = 'You would like to book flight from ' + intentObj.slots.Source.value + ' to ' +
                intentObj.slots.Destination.value + ', is that correct?';
                const cardTitle = 'Booking Summary';
                const repromptSpeech = speechOutput;
                const cardContent = speechOutput;
                this.emit(':confirmIntentWithCard', speechOutput, repromptSpeech, cardTitle, cardContent);
            } else {
                // Users denies the confirmation of intent. May be value of the slots are not correct.
                handleIntentConfimationDenial();
            }
        } else {
            handlePlanMyTripIntentAllSlotsAndIntentAreConfirmed();
        }
    }
};

Additional documentation about Dialog interface can be found here.

Display Interface

Alexa provides several Display templates to support a wide range of presentations. Currently, there are two categories of Display templates:

  • BodyTemplate displays text and images which cannot be made selectable. Currently has four options
  • BodyTemplate1
  • BodyTemplate2
  • BodyTemplate3
  • BodyTemplate6
  • BodyTemplate7
  • ListTemplate displays a scrollable list of items, each with associated text and optional images. These images can be made selectable. Currently has two options:
  • ListTemplate1
  • ListTemplate2

Developers must include Display.RenderTemplate directive in their skill responses. Template Builders are now included in alexa-sdk in the templateBuilders namespace. These provide a set of helper methods to build the JSON template for the Display.RenderTemplate directive. In the example below we use the BodyTemplate1Builder to build the Body template.

const Alexa = require('alexa-sdk');
// utility methods for creating Image and TextField objects
const makePlainText = Alexa.utils.TextUtils.makePlainText;
const makeImage = Alexa.utils.ImageUtils.makeImage;
 
// ...
'LaunchRequest' : function() {
    const builder = new Alexa.templateBuilders.BodyTemplate1Builder();
 
    const template = builder.setTitle('My BodyTemplate1')
                            .setBackgroundImage(makeImage('http://url/to/my/img.png'))
                            .setTextContent(makePlainText('Text content'))
                            .build();
 
    this.response.speak('Rendering a body template!')
                .renderTemplate(template);
    this.emit(':responseReady');
}

We've added helper utility methods to build Image and TextField objects. They are located in the Alexa.utils namespace.

const ImageUtils = require('alexa-sdk').utils.ImageUtils;
 
// Outputs an image with a single source
ImageUtils.makeImage(url, widthPixels, heightPixels, size, description);
/**
Outputs {
    contentDescription : '<description>'
    sources : [
        {
            url : '<url>',
            widthPixels : '<widthPixels>',
            heightPixels : '<heightPixels>',
            size : '<size>'
        }
    ]
}
*/
 
ImageUtils.makeImages(imgArr, description);
/**
Outputs {
    contentDescription : '<description>'
    sources : <imgArr> // array of {url, size, widthPixels, heightPixels}
}
*/
 
 
const TextUtils = require('alexa-sdk').utils.TextUtils;
 
TextUtils.makePlainText('my plain text field');
/**
Outputs {
    text : 'my plain text field',
    type : 'PlainText'
}
*/
 
TextUtils.makeRichText('my rich text field');
/**
Outputs {
    text : 'my rich text field',
    type : 'RichText'
}
*/
 

In the next example, we will use ListTemplate1Builder and ListItemBuilder to build ListTemplate1.

const Alexa = require('alexa-sdk');
const makePlainText = Alexa.utils.TextUtils.makePlainText;
const makeImage = Alexa.utils.ImageUtils.makeImage;
// ...
'LaunchRequest' : function() {
    const itemImage = makeImage('https://url/to/imageResource', imageWidth, imageHeight);
    const listItemBuilder = new Alexa.templateBuilders.ListItemBuilder();
    const listTemplateBuilder = new Alexa.templateBuilders.ListTemplate1Builder();
    listItemBuilder.addItem(itemImage, 'listItemToken1', makePlainText('List Item 1'));
    listItemBuilder.addItem(itemImage, 'listItemToken2', makePlainText('List Item 2'));
    listItemBuilder.addItem(itemImage, 'listItemToken3', makePlainText('List Item 3'));
    listItemBuilder.addItem(itemImage, 'listItemToken4', makePlainText('List Item 4'));
    const listItems = listItemBuilder.build();
    const listTemplate = listTemplateBuilder.setToken('listToken')
     .setTitle('listTemplate1')
     .setListItems(listItems)
     .build();
    this.response.speak('Rendering a list template!')
     .renderTemplate(listTemplate);
    this.emit(':responseReady');
}

Sending a Display.RenderTemplate directive to a headless device (like an echo) will result in an invalid directive error being thrown. To check whether a device supports a particular directive, you can check the device's supportedInterfaces property.

const handler = {
    'LaunchRequest' : function() {
 
    this.response.speak('Hello there');
 
    // Display.RenderTemplate directives can be added to the response
    if (this.event.context.System.device.supportedInterfaces.Display) {
        //... build mytemplate using TemplateBuilder
        this.response.renderTemplate(myTemplate);
    }
 
    this.emit(':responseReady');
    }
};

Similarly for video, you check if VideoApp is a supported interface of the device

const handler = {
    'PlayVideoIntent' : function() {
 
    // VideoApp.Play directives can be added to the response
    if (this.event.context.System.device.supportedInterfaces.VideoApp) {
        this.response.playVideo('http://path/to/my/video.mp4');
    } else {
        this.response.speak("The video cannot be played on your device. " +
        "To watch this video, try launching the skill from your echo show device.");
    }
 
        this.emit(':responseReady');
    }
};

Additional documentation on Display interface can be found here.

Playback Controller Interface

The PlaybackController interface enables skills to handles requests sent when a customer interacts with player controls such as buttons on a device or a remote control. Those requests are different from normal voice requests such as "Alexa, next song" which are standard intent requests. In order to enable skill to handle PlaybackController requests, developers must implement PlaybackController interface in Alexa Node.js SDK.

const handlers = {
    'PlaybackController.NextCommandIssued' : function() {
        //Your skill can respond to NextCommandIssued with any AudioPlayer directive.
    },
    'PlaybackController.PauseCommandIssued' : function() {
        //Your skill can respond to PauseCommandIssued with any AudioPlayer directive.
    },
    'PlaybackController.PlayCommandIssued' : function() {
        //Your skill can respond to PlayCommandIssued with any AudioPlayer directive.
    },
    'PlaybackController.PreviousCommandIssued' : function() {
        //Your skill can respond to PreviousCommandIssued with any AudioPlayer directive.
    },
    'System.ExceptionEncountered' : function() {
        //Your skill cannot return a response to System.ExceptionEncountered.
    }
};

Additional documentation about PlaybackController interface can be found here.

VideoApp Interface

To stream native video files on Echo Show, developers must send VideoApp.Launch directive. Alexa Node.js SDK provides a function in responseBuilder, to help build the JSON response object. Here is an example to stream video:

//...
'LaunchRequest' : function() {
    const videoSource = 'https://url/to/videosource';
    const metadata = {
     'title': 'Title for Sample Video',
     'subtitle': 'Secondary Title for Sample Video'
    };
    this.response.playVideo(videoSource metadata);
    this.emit(':responseReady');
}

Additional documentation on VideoApp interface can be found here.

Skill and List Events

Skill developers have the capability to integrate with Alexa skill events directly. If the skill is subscribed to these events, the skill is notified when an event occurs.

In order to use events in your skill service, you must set up access to the Alexa Skill Management API (SMAPI) as described in Add Events to Your Skill With SMAPI.

Skill and List Events come out of session. Once your skill has been set up to receive these events. You can specify behaviour by adding the event names to your default event handler.

const handlers = {
    'AlexaSkillEvent.SkillEnabled' : function() {
        const userId = this.event.context.System.user.userId;
        console.log(`skill was enabled for user: ${userId}`);
    },
    'AlexaHouseholdListEvent.ItemsCreated' : function() {
        const listId = this.event.request.body.listId;
        const listItemIds = this.event.request.body.listItemIds;
        console.log(`The items: ${JSON.stringify(listItemIds)} were added to list ${listId}`);
    },
    'AlexaHouseholdListEvent.ListCreated' : function() {
        const listId = this.event.request.body.listId;
        console.log(`The new list: ${JSON.stringify(listId)} was created`);
    }
    //...
};
 
exports.handler = function(event, context, callback) {
    const alexa = Alexa.handler(event, context, callback);
    alexa.registerHandlers(handlers);
    alexa.execute();
};

We've created a sample skill and walk-through to guide you through the process of subscribing to skill events.s

Services

Device Address Service

Alexa NodeJS SDK provides a DeviceAddressService helper class that utilizes Device Address API to retrieve customer device address information. Currently the following methods are provided:

getFullAddress(deviceId, apiEndpoint, token)
getCountryAndPostalCode(deviceId, apiEndpoint, token)

apiEndpoint and token can be retrieved from the request at this.event.context.System.apiEndpoint and this.event.context.System.user.permissions.consentToken

deviceId can also be retrieved from request at this.event.context.System.device.deviceId

const Alexa = require('alexa-sdk');
 
'DeviceAddressIntent': function () {
    if (this.event.context.System.user.permissions) {
        const token = this.event.context.System.user.permissions.consentToken;
        const apiEndpoint = this.event.context.System.apiEndpoint;
        const deviceId = this.event.context.System.device.deviceId;
 
        const das = new Alexa.services.DeviceAddressService();
        das.getFullAddress(deviceId, apiEndpoint, token)
        .then((data) => {
            this.response.speak('<address information>');
            console.log('Address get: ' + JSON.stringify(data));
            this.emit(':responseReady');
        })
        .catch((error) => {
            this.response.speak('I\'m sorry. Something went wrong.');
            this.emit(':responseReady');
            console.log(error.message);
        });
    } else {
        this.response.speak('Please grant skill permissions to access your device address.');
        this.emit(':responseReady');
    }
}

List Management Service

Alexa customers have access to two default lists: Alexa to-do and Alexa shopping. In addition, Alexa customer can create and manage custom lists in a skill that supports that.

Alexa NodeJS SDK provides a ListManagementService helper class to help developer create skills that manage default and custom Alexa lists more easily. Currently the following methods are provided:

getListsMetadata(token)
createList(listObject, token)
getList(listId, itemStatus, token)
updateList(listId, listObject, token)
deleteList(listId, token)
createListItem(listId, listItemObject, token)
getListItem(listId, itemId, token)
updateListItem(listId, itemId, listItemObject, token)
deleteListItem(listId, itemId, token)

token can be retrieved from the request at this.event.context.System.user.permissions.consentToken

listId can be retrieved from a GetListsMetadata call. itemId can be retrieved from a GetList call

const Alexa = require('alexa-sdk');
 
function getListsMetadata(token) {
    const lms = new Alexa.services.ListManagementService();
    lms.getListsMetadata(token)
    .then((data) => {
        console.log('List retrieved: ' + JSON.stringify(data));
        this.context.succeed();
    })
    .catch((error) => {
        console.log(error.message);
    });
};

Directive Service

enqueue(directive, endpoint, token)

Returns a directive to an Alexa device asynchronously during skill execution. It currently accepts speak directives only, with both SSML (inclusive of MP3 audio) and plain text output formats being supported. Directives can only be returned to the originating device when the skill is active. apiEndpoint and token parameters can be retrieved from the request at this.event.context.System.apiEndpoint and this.event.context.System.apiAccessToken respectively.

  • The response speech should be limited to 600 characters.
  • Any audio snippets referenced in SSML should be limited to 30 seconds.
  • There is no limit on the number of directives that a skill can send through the directive service. If necessary, skills can send multiple requests for each execution.
  • The directive service does not contain any deduplication processing, so we do not recommend any form of retry processing as it may result in users receiving the same directive multiple times.
const Alexa = require('alexa-sdk');
 
const handlers = {
    'SearchIntent' : function() {
        const requestId = this.event.request.requestId;
        const token = this.event.context.System.apiAccessToken;
        const endpoint = this.event.context.System.apiEndpoint;
        const ds = new Alexa.services.DirectiveService();
 
        const directive = new Alexa.directives.VoicePlayerSpeakDirective(requestId, "Please wait...");
        const progressiveResponse = ds.enqueue(directive, endpoint, token)
        .catch((err) => {
            // catch API errors so skill processing an continue
        });
        const serviceCall = callMyService();
 
        Promise.all([progressiveResponse, serviceCall])
        .then(() => {
            this.response.speak('I found the following results');
            this.emit(':responseReady');
        });
    }
};
 

Extend Features

Skill State Management

Alexa-sdk use state manager to route the incoming intents to the correct function handler. State is stored as a string in the session attributes indicating the current state of the skill. You can emulate the built-in intent routing by appending the state string to the intent name when defining your intent handlers, but alexa-sdk helps do that for you.

Let's take a sample skill highlowgame as an example to explain how state management works in SDK. In this skill, the customer will guess a number and the Alexa will tell if the number is higher or lower. It will also tell how many times the customer has played. It has two states 'start' and 'guess':

const states = {
    GUESSMODE: '_GUESSMODE', // User is trying to guess the number.
    STARTMODE: '_STARTMODE' // Prompt the user to start or restart the game.
};

The NewSession handler in newSessionHandlers will short-cut any incoming intent or launch requests and route them to this handler.

const newSessionHandlers = {
    'NewSession': function() {
        if(Object.keys(this.attributes).length === 0) { // Check if it's the first time the skill has been invoked
            this.attributes['endedSessionCount'] = 0;
            this.attributes['gamesPlayed'] = 0;
        }
        this.handler.state = states.STARTMODE;
        this.response.speak('Welcome to High Low guessing game. You have played '
                        + this.attributes['gamesPlayed'].toString() + ' times. Would you like to play?')
                    .listen('Say yes to start the game or no to quit.');
        this.emit(':responseReady');
    }
};

Notice that when a new session is created we simply set the state of our skill into STARTMODE using this.handler.state. The skills state will automatically be persisted in your skill's session attributes, and will be optionally persisted across sessions if you set a DynamoDB table.

It is also important to point out that NewSession is a great catch-all behavior and a good entry point but it is not required. NewSession will only be invoked if a handler with that name is defined. Each state you define can have its own NewSession handler which will be invoked if you are using the built-in persistence. In the above example we could define different NewSession behavior for both states.STARTMODE and states.GUESSMODE giving us added flexibility.

In order to define intents that will respond to the different states of our skill, we need to use the Alexa.CreateStateHandler function. Any intent handlers defined here will only work when the skill is in a specific state, giving us even greater flexibility!

For example, if we are in the GUESSMODE state we defined above we want to handle a user responding to a question. This can be done using StateHandlers like this:

const guessModeHandlers = Alexa.CreateStateHandler(states.GUESSMODE, {
 
'NewSession': function () {
    this.handler.state = '';
    this.emitWithState('NewSession'); // Equivalent to the Start Mode NewSession handler
},
 
'NumberGuessIntent': function() {
    const guessNum = parseInt(this.event.request.intent.slots.number.value);
    const targetNum = this.attributes['guessNumber'];
 
    console.log('user guessed: ' + guessNum);
 
    if(guessNum > targetNum){
        this.emit('TooHigh', guessNum);
    } else if( guessNum < targetNum){
        this.emit('TooLow', guessNum);
    } else if (guessNum === targetNum){
        // With a callback, use the arrow function to preserve the correct 'this' context
        this.emit('JustRight', () => {
            this.response.speak(guessNum.toString() + 'is correct! Would you like to play a new game?')
                        .listen('Say yes to start a new game, or no to end the game.');
            this.emit(':responseReady');
        });
    } else {
        this.emit('NotANum');
    }
},
 
'AMAZON.HelpIntent': function() {
    this.response.speak('I am thinking of a number between zero and one hundred, try to guess and I will tell you' +
    ' if it is higher or lower.')
                .listen('Try saying a number.');
    this.emit(':responseReady');
},
 
'SessionEndedRequest': function () {
    console.log('session ended!');
    this.attributes['endedSessionCount'] += 1;
    this.emit(':saveState', true); // Be sure to call :saveState to persist your session attributes in DynamoDB
},
 
'Unhandled': function() {
    this.response.speak('Sorry, I didn\'t get that. Try saying a number.')
                .listen('Try saying a number.');
    this.emit(':responseReady');
}
});

On the flip side, if I am in STARTMODE I can define my StateHandlers to be the following:

const startGameHandlers = Alexa.CreateStateHandler(states.STARTMODE, {
 
    'NewSession': function () {
        this.emit('NewSession'); // Uses the handler in newSessionHandlers
    },
 
    'AMAZON.HelpIntent': function() {
        const message = 'I will think of a number between zero and one hundred, try to guess and I will tell you if it' +
        ' is higher or lower. Do you want to start the game?';
        this.response.speak(message)
                    .listen(message);
        this.emit(':responseReady');
    },
 
    'AMAZON.YesIntent': function() {
        this.attributes['guessNumber'] = Math.floor(Math.random() * 100);
        this.handler.state = states.GUESSMODE;
        this.response.speak('Great! ' + 'Try saying a number to start the game.')
                    .listen('Try saying a number.');
        this.emit(':responseReady');
    },
 
    'AMAZON.NoIntent': function() {
        this.response.speak('Ok, see you next time!');
        this.emit(':responseReady');
    },
 
    'SessionEndedRequest': function () {
        console.log('session ended!');
        this.attributes['endedSessionCount'] += 1;
        this.emit(':saveState', true);
    },
 
    'Unhandled': function() {
        const message = 'Say yes to continue, or no to end the game.';
        this.response.speak(message)
                    .listen(message);
        this.emit(':responseReady');
    }
});

Take a look at how AMAZON.YesIntent and AMAZON.NoIntent are not defined in the guessModeHandlers object, since it doesn't make sense for a 'yes' or 'no' response in this state. Those intents will be caught by the Unhandled handler.

Also, notice the different behavior for NewSession and Unhandled across both states? In this game, we 'reset' the state by calling a NewSession handler defined in the newSessionHandlers object. You can also skip defining it and alexa-sdk will call the intent handler for the current state. Just remember to register your State Handlers before you call alexa.execute() or they will not be found.

Your attributes will be automatically saved when you end the session, but if the user ends the session you have to emit the :saveState event (this.emit(':saveState', true)) to force a save. You should do this in your SessionEndedRequest handler which is called when the user ends the session by saying 'quit' or timing out. Take a look at the example above.

If you want to explicitly reset the state, the following code should work:

this.handler.state = '' // delete this.handler.state might cause reference errors
delete this.attributes['STATE'];

Persisting Skill Attributes through DynamoDB

Many of you would like to persist your session attribute values into storage for further use. Alexa-sdk integrates directly with Amazon DynamoDB (a NoSQL database service) to enable you to do this with a single line of code.

Simply set the name of the DynamoDB table on your alexa object before you call alexa.execute.

exports.handler = function (event, context, callback) {
    const alexa = Alexa.handler(event, context, callback);
    alexa.appId = appId;
    alexa.dynamoDBTableName = 'YourTableName'; // That's it!
    alexa.registerHandlers(State1Handlers, State2Handlers);
    alexa.execute();
};

Then later on to set a value you simply need to call into the attributes property of the alexa object. No more separate put and get functions!

this.attributes['yourAttribute'] = 'value';

You can create the table manually beforehand or simply give your Lambda function DynamoDB create table permissions and it will happen automatically. Just remember it can take a minute or so for the table to be created on the first invocation. If you create the table manually, the Primary Key must be a string value called "userId".

Note: If you host your skill on lambda and choose to persist skill attributes through DynamoDB, please make sure the excution role of lambda function includes access to DynamoDB.

Adding Multi-Language Support for Skill

Let's take the Hello World example here. Define all user-facing language strings in the following format.

const languageStrings = {
    'en-GB': {
        'translation': {
            'SAY_HELLO_MESSAGE' : 'Hello World!'
        }
    },
    'en-US': {
        'translation': {
            'SAY_HELLO_MESSAGE' : 'Hello World!'
        }
    },
    'de-DE': {
        'translation': {
            'SAY_HELLO_MESSAGE' : 'Hallo Welt!'
        }
    }
};

To enable string internationalization features in Alexa-sdk, set resources to the object we created above.

exports.handler = function(event, context, callback) {
    const alexa = Alexa.handler(event, context);
    alexa.appId = appId;
    // To enable string internationalization (i18n) features, set a resources object.
    alexa.resources = languageStrings;
    alexa.registerHandlers(handlers);
    alexa.execute();
};

Once you are done defining and enabling language strings, you can access these strings using the this.t() function. Strings will be rendered in the language that matches the locale of the incoming request.

const handlers = {
    'LaunchRequest': function () {
        this.emit('SayHello');
    },
    'HelloWorldIntent': function () {
        this.emit('SayHello');
    },
    'SayHello': function () {
        this.response.speak(this.t('SAY_HELLO_MESSAGE'));
        this.emit(':responseReady');
    }
};

For more infomation about developing and deploying skills in multiple languages, please go here.

Device ID Support

When a customer enables your Alexa skill, your skill can obtain the customer’s permission to use address data associated with the customer’s Alexa device. You can then use this address data to provide key functionality for the skill, or to enhance the customer experience.

The deviceId is now exposed through the context object in each request and can be accessed in any intent handler through this.event.context.System.device.deviceId. See the Address API sample skill to see how we leveraged the deviceId and the Address API to use a user's device address in a skill.

Speechcons (Interjections)

Speechcons are special words and phrases that Alexa pronounces more expressively. In order to use them you can just include the SSML markup in the text to emit.

  • this.emit(':tell', 'Sometimes when I look at the Alexa skills you have all taught me, I just have to say, <say-as interpret-as="interjection">Bazinga.</say-as> ');
  • this.emit(':tell', '<say-as interpret-as="interjection">Oh boy</say-as><break time="1s"/> this is just an example.');

Speechcons are supported for English (US), English (UK), English (India), and German.

Setting up your development environment

  • Requirements
  • Gulp & mocha npm install -g gulp mocha
  • Run npm install to pull down stuff
  • run gulp to run tests/linter

For more information about getting started with the Alexa Skills Kit, check out the following additional assets:

Alexa Dev Chat Podcast

Alexa Training with Big Nerd Ranch

Alexa Skills Kit (ASK)

Alexa Developer Forums

Training for the Alexa Skills Kit

-Dave ( @TheDaveDev)