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Developing Your First Skill

This guide walks you through developing your first skill with the ASK SDK v2 for Java.

Prerequisites

  • An Amazon Developer account. This is required to create and configure Alexa skills.
  • An Amazon Web Services (AWS) account. This guide will walk you through hosting a skill on AWS Lambda.
  • A Maven project with a dependency on the SDK as described in the Setting up the ASK SDK v2 for Java section. The sample skill requires either the standard SDK distribution, or if customizing your dependencies, requires that you include the support modules for the core SDK and AWS Lambda.

Implementing request handlers

First we'll create the request handlers needed to handle the different types of incoming requests to our skill.

LaunchRequest handler

The following code example shows how to configure a handler to be invoked when the skill receives a LaunchRequest. The LaunchRequest event occurs when the skill is invoked without a specific intent.

package com.amazon.ask.helloworld.handlers;

import com.amazon.ask.dispatcher.request.handler.HandlerInput;
import com.amazon.ask.dispatcher.request.handler.RequestHandler;
import com.amazon.ask.model.LaunchRequest;
import com.amazon.ask.model.Response;
import com.amazon.ask.request.Predicates;

import java.util.Optional;

public class LaunchRequestHandler implements RequestHandler {

    @Override
    public boolean canHandle(HandlerInput input) {
        return input.matches(Predicates.requestType(LaunchRequest.class));
    }

    @Override
    public Optional<Response> handle(HandlerInput input) {
        String speechText = "Welcome to the Alexa Skills Kit, you can say hello";
        return input.getResponseBuilder()
                .withSpeech(speechText)
                .withSimpleCard("HelloWorld", speechText)
                .withReprompt(speechText)
                .build();
    }

}

The canHandle method returns true if the incoming request is a LaunchRequest. The handle method generates and returns a basic greeting response with response objects such as Speech, Card, and Reprompt which you can find more information here.

Alternatively, you can create a handler for built-in intents using one of the Typed Request Handlers.

package com.amazon.ask.helloworld.handlers;

import com.amazon.ask.dispatcher.request.handler.HandlerInput;
import com.amazon.ask.dispatcher.request.handler.RequestHandler;
import com.amazon.ask.model.LaunchRequest;
import com.amazon.ask.model.Response;
import com.amazon.ask.request.Predicates;

import java.util.Optional;

public class LaunchRequestHandler implements com.amazon.ask.dispatcher.request.handler.impl.LaunchRequestHandler {

    @Override
    public boolean canHandle(HandlerInput input, LaunchRequest launchRequest) {
        return true;
    }

    @Override
    public Optional<Response> handle(HandlerInput input, LaunchRequest launchRequest) {
        // return response.
    }

}

HelloWorldIntent handler

The following code example shows how to configure a handler to be invoked when the skill receives the HelloWorldIntent.

package com.amazon.ask.helloworld.handlers;

import com.amazon.ask.dispatcher.request.handler.HandlerInput;
import com.amazon.ask.dispatcher.request.handler.RequestHandler;
import com.amazon.ask.model.Response;
import com.amazon.ask.request.Predicates;

import java.util.Optional;

public class HelloWorldIntentHandler implements RequestHandler {

    @Override
    public boolean canHandle(HandlerInput input) {
        return input.matches(Predicates.intentName("HelloWorldIntent"));
    }

    @Override
    public Optional<Response> handle(HandlerInput input) {
        String speechText = "Hello world";
        return input.getResponseBuilder()
                .withSpeech(speechText)
                .withSimpleCard("HelloWorld", speechText)
                .build();
    }

}

The handler's canHandle method detects if the incoming request is an IntentRequest, and returns true if the intent name is HelloWorldIntent. A basic "Hello world" response is then generated and returned.

An example of the HelloWorldIntentHandler created using Typed Request Handler can be found here.

HelpIntent handler

The following code example shows how to configure a handler to be invoked when the skill receives the built in intent AMAZON.HelpIntent.

package com.amazon.ask.helloworld.handlers;

import com.amazon.ask.dispatcher.request.handler.HandlerInput;
import com.amazon.ask.dispatcher.request.handler.RequestHandler;
import com.amazon.ask.model.Response;
import static com.amazon.ask.request.Predicates.intentName;

import java.util.Optional;

public class HelpIntentHandler implements RequestHandler {

    @Override
    public boolean canHandle(HandlerInput input) {
        return input.matches(intentName("AMAZON.HelpIntent"));
    }

    @Override
    public Optional<Response> handle(HandlerInput input) {
        String speechText = "You can say hello to me!";
        return input.getResponseBuilder()
                .withSpeech(speechText)
                .withSimpleCard("HelloWorld", speechText)
                .withReprompt(speechText)
                .build();
    }
}

Similar to the previous handler, this handler matches an IntentRequest with the expected intent name. Basic help instructions are returned.

CancelandStopIntent handler

This handler is very similar to the HelpIntent handler, as it will also be triggered by built in intents. But in this case, we decided to use a single handler to respond to two different intents, Amazon.CancelIntent and Amazon.StopIntent.

package com.amazon.ask.helloworld.handlers;

import com.amazon.ask.dispatcher.request.handler.HandlerInput;
import com.amazon.ask.dispatcher.request.handler.RequestHandler;
import com.amazon.ask.model.Response;
import static com.amazon.ask.request.Predicates.intentName;

import java.util.Optional;

public class CancelandStopIntentHandler implements RequestHandler {

    @Override
    public boolean canHandle(HandlerInput input) {
        return input.matches(intentName("AMAZON.StopIntent").or(intentName("AMAZON.CancelIntent")));
    }

    @Override
    public Optional<Response> handle(HandlerInput input) {
        return input.getResponseBuilder()
                .withSpeech("Goodbye")
                .withSimpleCard("HelloWorld", "Goodbye")
                .build();
    }
}

Our response to both these intents will be the same, so having a single handler reduces repetitive code.

FallbackIntent handler

The following code example shows how to configure a handler to be invoked when the skill receives the built in intent AMAZON.FallbackIntent. Please note that this intent is only available in English (US) currently.

package com.amazon.ask.helloworld.handlers;

import com.amazon.ask.dispatcher.request.handler.HandlerInput;
import com.amazon.ask.dispatcher.request.handler.RequestHandler;
import com.amazon.ask.model.Response;

import java.util.Optional;

import static com.amazon.ask.request.Predicates.intentName;

public class FallbackIntentHandler implements RequestHandler {

    @Override
    public boolean canHandle(HandlerInput input) {
        return input.matches(intentName("AMAZON.FallbackIntent"));
    }

    @Override
    public Optional<Response> handle(HandlerInput input) {
        String speechText = "Sorry, I don't know that. You can say try saying help!";
        return input.getResponseBuilder()
                .withSpeech(speechText)
                .withSimpleCard("HelloWorld", speechText)
                .withReprompt(speechText)
                .build();
    }
}

SessionEndedRequest handler

Despite not being able to send a response back after receiving a SessionEndedRequest, this handler gives us a good place for us to put our cleanup logic.

package com.amazon.ask.helloworld.handlers;

import com.amazon.ask.dispatcher.request.handler.HandlerInput;
import com.amazon.ask.dispatcher.request.handler.RequestHandler;
import com.amazon.ask.model.Response;
import com.amazon.ask.model.SessionEndedRequest;
import static com.amazon.ask.request.Predicates.requestType;

import java.util.Optional;

public class SessionEndedRequestHandler implements RequestHandler {

    @Override
    public boolean canHandle(HandlerInput input) {
        return input.matches(requestType(SessionEndedRequest.class));
    }

    @Override
    public Optional<Response> handle(HandlerInput input) {
        // any cleanup logic goes here
        return input.getResponseBuilder().build();
    }
}

Implementing the SkillStreamHandler

The stream handler is the entry point for your AWS Lambda function. Every request made by an end user to Alexa which invokes your skill will pass through this class, into your configured Skill instance, and then be forwarded to the handler appropriate for the request. Some examples might be a HelloWorldIntentHandler, HelpIntentHandler, or a LaunchRequestHandler. As part of the request handling process, request and response interceptors and exception handlers may also be invoked as needed and depending on your skill's configuration.

The SkillStreamHandler is an SDK provided subclass of AWS Lambda's RequestStreamHandler that takes care of boilerplate logic for serializing and deserializing Alexa requests. This means that your skill's stream handler class only needs to extend the SkillStreamHandler and pass it a Skill instance configured with your handlers and other configuration. Once AWS Lambda is configured to use your stream handler class as its entry point, all requests will be routed through this Skill instance into the appropriate handlers.

The following HelloWorldStreamHandler creates an SDK Skill instance configured with the request handlers we just created.

package com.amazon.ask.helloworld;

import com.amazon.ask.Skill;
import com.amazon.ask.Skills;
import com.amazon.ask.SkillStreamHandler;

import com.amazon.ask.helloworld.handlers.CancelandStopIntentHandler;
import com.amazon.ask.helloworld.handlers.HelloWorldIntentHandler;
import com.amazon.ask.helloworld.handlers.HelpIntentHandler;
import com.amazon.ask.helloworld.handlers.SessionEndedRequestHandler;
import com.amazon.ask.helloworld.handlers.LaunchRequestHandler;

public class HelloWorldStreamHandler extends SkillStreamHandler {

    private static Skill getSkill() {
        return Skills.standard()
                .addRequestHandlers(
                        new CancelandStopIntentHandler(),
                        new HelloWorldIntentHandler(),
                        new HelpIntentHandler(),
                        new LaunchRequestHandler(),
                        new SessionEndedRequestHandler())
                .build();
    }

    public HelloWorldStreamHandler() {
        super(getSkill());
    }

}

The getSkill method creates an SDK instance using the Skills.standard builder. We create instances of our request handlers and register them with our skill with the addRequestHandlers builder method. The HelloWorldStreamHandler constructor passes the constructed Skill instance to the constructor for the superclass SkillStreamHandler.

The fully qualified class name of your stream handler class consists of the package and class name and is required when configuring your AWS Lambda function. In this example, the fully qualified class name is com.amazon.ask.helloworld.HelloWorldStreamHandler.

Building the skill

With our skill code complete, we are ready to build our skill project. To prepare the skill for upload to AWS Lambda, we'll need to produce a JAR file that contains the skill plus all necessary dependencies. To do so, open a terminal and navigate to your Maven project's top level directory that contains pom.xml, and run the following command:

mvn org.apache.maven.plugins:maven-assembly-plugin:2.6:assembly -DdescriptorId=jar-with-dependencies package

This command produces a <my_project_name>.<my_project_version>-jar-with-dependencies.jar file in the target directory.

Uploading your skill to AWS Lambda

  1. If you do not already have an account on AWS, go to Amazon Web Services and create an account.
  2. Log in to the AWS Management Console and navigate to AWS Lambda.
  3. Click the region drop-down in the upper-right corner of the console and select one of the regions supported for Alexa skills: Asia Pacific (Tokyo), EU (Ireland), US East (N. Virginia), or US West (Oregon).
  4. If you have no Lambda functions yet, click Get Started Now. Otherwise, click Create function.
  5. Make sure to confirm that "Author from scratch" option is selected.
  6. Enter a Name for the function.
  7. Select the Role for the function. This defines the AWS resources the function can access.
  8. Select the language you want to use for the Runtime which is Java 8 in our case.
  9. Click "Create function".
  10. Configure the Alexa Skills Kit trigger for the function as described here. Make sure you have completed adding an Alexa Skills Kit Trigger.
  11. Upload the JAR file produced in the previous step under Function code.
  12. Fill in the Handler information with fully qualified class name of your stream handler class.
  13. Finally, copy the ARN of your AWS Lambda function because you will need it when configuring your skill in the Amazon Developer console. You can find this on the top right corner.

Configuring and testing your skill

Now that the skill code has been uploaded to AWS Lambda we're ready to configure the skill with Alexa. First, navigate to the Alexa Skills Kit Developer Console. Click the "Create Skill" button in the upper right. Enter "HelloWorld" as your skill name. On the next page, select "Custom" and click "Create skill".

Now we're ready to define the interaction model for the skill. Under "Invocation" tab on the left side, define your Skill Invocation Name to be greeter.

Now it's time to add an intent to the skill. Click the "Add" button under the Intents section of the Interaction Model. Leave "Create custom intent" selected, enter "HelloWorldIntent" for the intent name, and create the intent. Now it's time to add some sample utterances that will be used to invoke the intent. For this example, we've provided the following sample utterances, but feel free to add others.

say hello
say hello world
hello
say hi
say hi world
hi
how are you

Since AMAZON.CancelIntent, AMAZON.HelpIntent, and AMAZON.StopIntent are built-in Alexa intents, sample utterances do not need to be provided as they are automatically inherited.

The Developer Console alternately allows you to edit the entire skill model in JSON format by selecting "JSON Editor" on the navigation bar. For this sample, the following JSON schema can be used.

{
  "languageModel": {
    "intents": [
      {
        "name": "AMAZON.CancelIntent",
        "samples": []
      },
      {
        "name": "AMAZON.HelpIntent",
        "samples": []
      },
      {
        "name": "AMAZON.StopIntent",
        "samples": []
      },
      {
        "name": "HelloWorldIntent",
        "samples": [
          "say hello",
          "say hello world",
          "hello",
          "say hi",
          "say hi world",
          "hi",
          "how are you"
        ],
        "slots": []
      }
    ],
    "invocationName": "greeter"
  }
}

Once you're done editing the interaction model don't forget to save and build the model.

Let's move on to the skill configuration section. Under "Endpoint" select "AWS Lambda ARN" and paste in the ARN of the function you created previously. The rest of the settings can be left at their default values. Click "Save Endpoints" and proceed to the next section.

Finally you're ready to test the skill! In the "Test" tab of the developer console you can simulate requests, in text and voice form, to your skill. Use the invocation name along with one of the sample utterances we just configured as a guide. For example, "tell greeter to say hello" should result in your skill responding with "Hello world". You should also be able to go to the Echo webpage and see your skill listed under "Your Skills", where you can enable the skill on your account for testing from an Alexa enabled device.

At this point, feel free to start experimenting with your Intent Schema as well as the corresponding request handlers in your skill's implementation. Once you're finished iterating, you can optionally choose to move on to the process of getting your skill certified and published so it can be used by Alexa users worldwide.