Making SUSI Alexa skill as an express app

Making SUSI Alexa skill as an express app

Previously SUSI Alexa skill was deployed using AWS Lambda service (Refer to this blog). Each SUSI.AI Bot should be deployed on Google cloud using Kubernetes. To accomplish that, we need to remove the dependency of the SUSI Alexa skill from AWS Lambda service. We need to make it an express app, to be able to deploy it to Google cloud. Let’s start with on how to achieve it:

SUSI Alexa skill:

We require three files to make the skill as an express app. The main entry point for the skill would be server.js file, which will serve the incoming request using two helper files alexa.js and handlers.js.

Server.js:

This file acts as the main entry point for the incoming request. We handle two type of requests using it, that are:

  1. Launch request
  2. Intent request

Launch request is triggered when a person utters “Alexa, open susi chat” , “Alexa, start susi chat”, “Alexa, launch susi chat” etc. This request is responded with an introductory phrase about SUSI.AI. To catch this request:

if (type === "LaunchRequest") {
        var endpoint = "http://api.susi.ai/susi/chat.json?q="+"Welcome"; // ENDPOINT GOES HERE
        
        http.get(endpoint, (response1) => {
            var body = "";
            response1.on("data", (chunk) => { body += chunk; });
            response1.on("end", () => {
                var viewCount;
                viewCount = JSON.parse(body).answers[0].actions[0].expression;
                endpoint = "http://api.susi.ai/susi/chat.json?q="+"Get+started"; // ENDPOINT GOES HERE
                body = "";
                http.get(endpoint, (response2) => {
                    response2.on("data", (chunk) => { body += chunk; });
                    response2.on("end", () => {
                        viewCount += JSON.parse(body);.answers[0].actions[0].expression;
                        response.say(viewCount,false);
                    });
                });
            });
        });
    }

Intent request gets triggered, when any other phrase is uttered by the user except Launch related phrases. We check if the intent triggered has a corresponding handler to handle the request. If the handler is found in handlers.js file, we call it passing the required arguments to the handler function. Let’s see how handlers make this step possible.

Handler.js:

This file decides on what function to run when a particular type of intent is triggered. As we have just one intent for our SUSI Alexa skill i.e. callSusiApi, we have just one function in our handlers.js file. During its execution, the first step we do is extract the query value:

let query = slots.query.value;

Depending upon the query value, we run its corresponding code. For example, in case of a generic query (i.e. any query except stop, cancel and help):

var endpoint = "http://api.susi.ai/susi/chat.json?q="+query; // ENDPOINT GOES HERE

http.get(endpoint, (response1) => {
    var body = "";
    response1.on("data", (chunk) => { body += chunk; });
    response1.on("end", () => {
        var data = JSON.parse(body);
        if(data.answers[0].actions[1]){
            // handle rss and table type results
        }
        else
        {
            viewCount = data.answers[0].actions[0].expression;
        }
        response.say(viewCount,true);
    });
});

At the end of the function we respond to the user with an answer to his/her query using:

response.say(viewCount,true);

Alexa.js:

When we get a request from the user, we pass that request and response object to this file. This file helps us wrap the required request properties into an object and return that back to the server file, which was the entry point for the request. Now, we can easily extract the properties in server file and work with those:

We extract the properties like this:

let session = req.body.session,
        intent,
        slots;
session.attributes = session.attributes || {};

if (req.body.request.intent) {
    intent = req.body.request.intent.name;
    slots = req.body.request.intent.slots;
}

Then we return the object back at the end:

return {
        type: req.body.request.type,
        intent: intent,
        slots: slots,
        session: session,
        response: {
            say: (text, shouldEndSession) => say(text, shouldEndSession),
            ask: (text, shouldEndSession) => say(text, shouldEndSession)
        }
    };

Great, we have made the SUSI Alexa skill as an express app. The next step is to do some changes in the configuration tab of our skill:

  1. Instead of Amazon resource number, we fill our webhook address here: 

  2. A new property shows up that is SSL certificate. As we are using Heroku for webhook services, we select the second option as shown below: 

  3. It’s time to test the skill: 

    This repository by Salesforce helped me a lot in making the SUSI skill as an express app.

    Resources:

    1. Developing Alexa Skills Locally with Node.js by Josh Skeen from Bignerdranch.
    2. Amazon Alexa Skills: Create a Custom Skill by Simon Coope from SJCNET.
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