react-ssml-dom

ReactSSML

Utilize the full power of React to develop voice UIs. ReactSSML provides a simple custom React renderer that let's you use React and JSX to create SSML output.

This project is brand new, so if you run into issues or have questions, open up an issue and let me know! Any feedback is highly appreciated.

Contents

• Motivation
• Installation Guide
• Demo
• Documentation
• Architecture
• Example Apps

🌟 Motivation

• Building SSML speech responses with strings is cumbersome.
• Let's treat voice apps as UI.
• Enable composition and declarative syntax.

I wrote a small article about my motivation.

What we hate

const reply = `
<speak>
 ${firstSession ? 'helloLong' : 'helloShort'}
 <audio src='https://s3-bucket/niceSound.mp3'/>
 ${i18n.t(keys.offerHelp)}
 ${showHint ? newFeatureHint : ''}
 ${i18n.t(keys.promptSearch)}
</speak>`;

What we want

<App>
  <SearchProvider>
    <Introduction long="{firstSession}" />
    <BrandedAudio />
    <OfferHelp />
    { showHint && <NewestFeatureHint />
    }
  </SearchProvider>
</App>

🚀 Installing ReactSSML

Get the package from npm.

npm i react-ssml-dom

Create an App component

import React from 'react';

const App = () => <s>Hello World</s>;

export default App;

Render your App

import ReactSMML, { Document, Node } from 'react-ssml-dom';

// create a document similar to the DOM's document
const ssmlDocument = new Document();
// create a root node similar to the body in HTML
const root = new Node('speak');
ssmlDocument.body = root;

ReactSMML.render(<App />, root);

Done!

console.log(ssmlDocument.toString());

<speak>
  <s>Hello World!</s>
</speak>

🌟 Try out the demo

Clone this repo and play around with the demo application

Get the source code

git clone https://github.com/andrelandgraf/react-ssml-dom.git

Build the demo

npm run build:demo

Run the demo

npm run start:demo

> react-ssml@1.0.2 start:demo /react-ssml
> node dist/main.js

Express backend listening on port 8888! 🚀

Express server is now running on port 8888!

Use Postman or a tool of your choice to hit the fulfillment endpoint.

You can find a collection of valid requests in index.http

If you are using VS Code, checkout this plugin to run curl commands with VS Code.

curl -X POST http://localhost:8888/hello-world

And there we go!

{
  "ssml": "<speak version=\"1.1\" xml:lang=\"en-US\" xmlns=\"http://www.w3.org/2001/10/synthesis\">Hello World!</speak>"
}

📖 Documentation

Content

• ReactSSML
• ssml-dom
  • Document
  • XMLDeclaration
  • Root
  • Node
  • TextNoode
• conversation
  • Conversation
  • builders
    • withRaw
    • withAoG

ReactSSML

ReactSSML works like ReactDOM. It provides one function render that takes your react App component and your ssml-dom node that your app should render in. Typically, that would be your root node.

import ReactSMML from 'react-ssml-dom';

ReactSMML.render(<App />, root);

ssml-dom: Document

Document works similar to the document global variable. Initialize a new Document with the following constructor parameters:

constructor

param	default	description
locale	'en-locale'	document locale
addDefaultRoot	true	if true, it will add a default Root node as the document body
includeProlog	false	if true, it will add a default XMLDeclaration to the document

import { Document } from 'react-ssml-dom';

// those are the default parameters
const doc = new Document('en-US', true, false);

toString {function}

Call the toString to create a string representation of the SSML document.

isReady {Promise}

At some point you want to return the SSML to your user. For that you have to know if the React app has the desired state. doc.isReady provides a Promise that can be awaited before returning the SSML. The promise can be resolved with doc.setReady().

Checkout ./index which makes use of await doc.isReady. In the demo, the React app get rendered serverside within an express.js endpoint. await doc.isReady is used before returning the SSML to the client. Within the demo app, the promise is resolved by calling doc.setReady(). This is useful if you have to fetch data in your React app and think the app will render a view times.

setReady {function}

Resolves the promise doc.isReady and can for example be called after your React app successfully fetched data and is about to render its final SSML.

Document PropType: documentType

Note: You can use the documentType propType if you are using prop-types in your project.

import { documentType } from 'react-ssml-dom';

const App = ({ doc }) => <>Current language is {doc.language}</>;

App.propTypes = {
  doc: documentType,
};

smml-dom: XMLDeclaration

By definition SSML documents start with a XML declaration. Some speech synthesizer will require a valid declaration to parse the SSML.

• Add a default XMLDeclaration to the Document by setting the includeProlog parameter to true
• You can always alter the XMLDeclaration like so:

import { Document } from 'react-ssml-dom';

const doc = new Document('en-US', true, false);
doc.includeProlog = true;
doc.xmlDeclaration.version = '1.1'; // '1.0' is the default

smml-dom: Root

Root extends Node and defaults its type to 'speak'. You can create your own Root node and set it to doc.body. Initialize a new Root node with the following constructor parameters:

constructor

param	default	description
locale	'en-locale'	document locale
addDefaults	true	if true, it will add default attributes to the node

The default attributes:

version="1.1"
xml:lang="en-US"
xmlns="http://www.w3.org/2001/10/synthesis"

import { Document, Root } from 'react-ssml-dom';

const doc = new Document('en-US', false, false);
// those are the default parameters
doc.body = new Root('en-US', false);

smml-dom: Node

Similar to a DOM node of the browser DOM implementation. It has a type and a list of attributes and can render to a string by calling toString.

type {string}

All possible SSML tags are allowed types.

toString {function}

smml-dom: TextNode

Similar to a DOM textNode of the browser DOM implementation. It has a text field and can render to a string by calling toString.

toString {function}

conversation: Conversation (optional)

Similar to the window global variable in the browser environment.

You don't need to work with the conversation model, it is entierly optional and might be abstracted into it's own package in the future. Conversation provides an abstraction layer for a voice dialog and could be a way for you to access the request (intent, parameters, ...) and the response (endConversation, reply, contexts, ...) of the ongoing conversation within your React component.

The idea is that all requests and responses can be abstracetd into the conversation model. Most likely you will use ReactSSML to create voice apps for Amazon Alexa, Google Assistant, or any other popular nlu provider or voice assistant. Conversation aims to provide an abstraction layer to and from any target environment.

This is how it works:

import { Conversation } from 'react-ssm-dom';
// parse request body (e.g. express.js request body) to conversation model
const conv = new Conversation(req.body);
// access common parameters of any voice environment
const intent = conv.intent;
conv.response.endConversation = false;
// and parse the final user response back to the target environment model
const payload = conv.buildPayload(ssmlReply);

Conversation Model

fields	default	type	description
locale	'en-locale'	string	the locale of the conversation
intent	undefined	string	the current intent of the user
target	undefined	string	the target env, e.g. default, aog, ...
parameters	{}	object	list of parameters / slots the user filled
originalRequest	undefined	object	the actual request object
user	undefined	object	the user object
queryText	undefined	string	the actual query of the user
sessionId	undefined	string	the sessionId unique across all conversations
response	{ reply: '', contexts: [], endConversation: true }	object	the response object that will be filled and sent back to the user

Conversation PropType: conversationType

Note: You can use conversationType propType if you are using the conversation object within your React app and want to utilize prop-types.

import { conversationType } from 'react-ssml-dom';

const App = ({ conv }) => <>Current intent is {conv.intent}</>;

App.propTypes = {
  conv: conversationType,
};

conversation: builders (withAoG, withRaw)

You can create your own builders to build a conversation model from your request and build a payload back from that conversation once your conversation is ready.

This package comes with a set of builders already:

• withRaw
• withAoG

conversation: builder withRaw

The default builder is registered by default. If no other builder canBuildConversation the default builder will try to build the conversation.

conversation: builder withAoG

A builder to parse the dialogflow actions on google request to the conversation model and the conversation back to a dialogflow response.

register a builder

You can register your custom builders or any of the builders of this package like so:

import { Conversation, withAoG } from 'react-smml-dom';

// similar to how express use works, you can add as many builders as you want
Conversation.useBuilder(withAoG);

useBuilder {function}

useBuilder takes two arguments.

param	default	description
builder	required!	the builder
map	{}	a map that can be used to help the builder parse to the conv model

A map for the withAoG builder could look like follows:

const aogMap = {
  parameters: {
    'geo-country': (value) => (Array.isArray(value) ? 'countries' : 'country'),
  },
};

This map will take any AoG parameter with the key geo-country and parse it depending on it's value as a parameter with the key name countries or country.

Build your own builder

a builder has to offer the following functions and fields:

fields	type	expected return value	parameters	description
target	string	-	-	the name of the target environment.
canBuildConversation	function	boolean	request	should return true if the builder can handle the given request and false if not, the first builder that return true will be picked to build the conversation.
buildConversation	function	object	request, map	should return an object with all the fields that the request can fill for the conversation.
buildPayload	function	object	conversation	should return the payload that can be sent to the user.

🔍 How it works

This project is using react-reconciler to implement a custom renderer for React.

See: ./src/ReactSSML.js which works like react-dom.

On top of that this project implements a (proof-of-concept) version of the web's DOM for SSML.

See: ./src/ssml-dom/*

The ./src/conversation/* folder implements a conversation model that abstracts away the target environment. You can think of the conversation object to something similar as the window on the web. On top of that it enables abstracting away the target environment. The vision is to use the same code base (React App) for Actions on Google, Alexa Skills and all possible target environments and translate the different requests into the conversation model.

The demo folder contains a demo React App. The demo express server runes via .index.js

Set receivedError in ./demo/Reply.jsx to true and see how the response SSML changes.

Also, try to set the timeout time in ./demo/Reply.jsx from 3000 to 8000 which is higher as our global timeout in index.js. See what happens to get an idea of how this project works.

🔛 Example Apps using ReactSSML

• Covid-19 Stats in SSML