Async Twilio Studio and serverless

process.js

const axios = require('axios');

// This is your new function. To start, set the name and path on the left.

exports.handler = async function(context, event, callback) {
  // Here's an example of setting up some TWiML to respond to with this function
	const twiml = `
      <?xml version="1.0" encoding="UTF-8"?>
      <Response>
          <Play>http://com.twilio.sounds.music.s3.amazonaws.com/ClockworkWaltz.mp3</Play>
      </Response>
  `.trim();

  axios.get(`https://defaultservice-4013.twil.io/slowFunc?callSID=${event.callSID}`);

  const client = context.getTwilioClient();
  client.calls(event.callSID).update({ twiml })
  .then(call => {
    console.log(call, " is the updated call")
    return callback(null, "twiml")
  })
  .catch(err => {
    console.log("I ended in an error:", err)
  })

};

slowFunc.js

const flowSid = "FWc3f0cae1142d2c6e36733b2231044062"
const axios = require('axios')

exports.handler = async function(context, event, callback) {
  axios.get("https://deelay.me/5000/http://echo.jsontest.com/score/1000")  
  .then(resp =>{
    console.log("score is", resp.score, resp);
    const twiml = `
      <?xml version="1.0" encoding="UTF-8"?>
      <Response>
          <Redirect>https://webhooks.twilio.com/v1/Accounts/${context.ACCOUNT_SID}/Flows/${flowSid}?FlowEvent=return&amp;score=${resp.data.score}</Redirect>
      </Response>
  `.trim();
    const client = context.getTwilioClient();
    client.calls(event.callSID).update({ twiml })
    .then(call =>{
      console.log("Done");
      return callback(null, "")
    })
  })  
};

studioFlow.json

{
  "description": "A New Flow",
  "states": [
    {
      "name": "Trigger",
      "type": "trigger",
      "transitions": [
        {
          "event": "incomingMessage"
        },
        {
          "next": "GreetUser",
          "event": "incomingCall"
        },
        {
          "event": "incomingConversationMessage"
        },
        {
          "event": "incomingRequest"
        },
        {
          "event": "incomingParent"
        }
      ],
      "properties": {
        "offset": {
          "x": 0,
          "y": 0
        }
      }
    },
    {
      "name": "GreetUser",
      "type": "say-play",
      "transitions": [
        {
          "next": "redirect_1",
          "event": "audioComplete"
        }
      ],
      "properties": {
        "voice": "alice",
        "offset": {
          "x": -370,
          "y": 250
        },
        "loop": 1,
        "say": "Hello. Thanks for calling. Please wait while we process your score",
        "language": "en-US"
      }
    },
    {
      "name": "say_play_3",
      "type": "say-play",
      "transitions": [
        {
          "event": "audioComplete"
        }
      ],
      "properties": {
        "voice": "alice",
        "offset": {
          "x": 350,
          "y": 730
        },
        "loop": 1,
        "say": "Thanks for waiting. Your score is {{widgets.redirect_1.score}}",
        "language": "en-US"
      }
    },
    {
      "name": "redirect_1",
      "type": "add-twiml-redirect",
      "transitions": [
        {
          "next": "say_play_3",
          "event": "return"
        },
        {
          "event": "timeout"
        },
        {
          "event": "fail"
        }
      ],
      "properties": {
        "offset": {
          "x": -50,
          "y": 460
        },
        "method": "GET",
        "url": "https://handler.twilio.com/twiml/EH4e929aa9c31353aa0a764bdd5d1481bf?callSID={{trigger.call.CallSid}}",
        "timeout": "14400"
      }
    }
  ],
  "initial_state": "Trigger",
  "flags": {
    "allow_concurrent_calls": true
  }
}

twimlBin.xml

<?xml version="1.0" encoding="UTF-8"?>
<Response>
  <Redirect>https://defaultservice-4013.twil.io/process?callSID={{callSID}}</Redirect>
</Response>