Using Plugins 1 - The platform-init Plugin ​

In this first tutorial on soundworks plugins, we will learn why and how to use the platform-init plugin, which aims to simplify the use of certain features (such as the Web Audio API) that require a user gesture to be properly initialized.

The tutorial requires basic knowledge of the soundworks wizard, so please refer to the getting started tutorial if you didn't check it yet.

Relevant documentation ​

• client.PluginManager
• server.PluginManager
• @soundworks/plugin-platform-init

Scaffolding the application and installing the plugin ​

First thing first, let's generate a new empty application with the @soundworks/create wizard. When the wizard will ask you for the name of the default client, enter the following information:

• Name it player
• Select the browser target
• Select the default template

cd /path/to/working/directory
npx @soundworks/create@latest plugin-platform-init

Once done, go to the directory and launch the soundworks wizard again to install the plugin:

cd plugin-platform-init
npx soundworks

Select the install / uninstall soundworks plugins entry:

Select the @soundworks/plugin-platform-init using the space bar:

And confirm:

After the installation has completed, you can exit the wizard by pressing Ctrl+C or by selecting the → exit entry.

npm install --save @soundworks/plugin-platform-init

If you open the package.json file, you should see the @soundworks/plugin-platform-init appearing under the dependencies key:

// package.json
  "dependencies": {
    "@ircam/sc-components": "^3.0.0-alpha.44",
    "@soundworks/core": "^4.0.0-alpha.0",
    "@soundworks/helpers": "^1.0.0-alpha.2",
    "@soundworks/plugin-platform-init": "^1.0.0-alpha.5",
    "json5": "^2.2.2",
    "lit": "^3.0.2"
  },

This file allows you and the node package manager (i.e. npm) to keep track of the dependencies of your project. Then, if you need to re-install the application dependencies (i.e. npm install) the plugin will be re-installed as well.

Registering the plugin into soundworks ​

Now that the plugin is installed as a dependency of our application, let's write the code to register the plugin into soundworks.

By design, all soundworks plugins always come with both a server-side component and a client-side component. Hence, you will always have to register the plugin on both side of your application.

Server-side registration ​

Let's start with the server-side part and write the following code in the src/server/index.js file. First let's import the server-side part of the plugin on top of the file:

// src/server/index.js
import '@soundworks/helpers/polyfills.js';
import { Server } from '@soundworks/core/server.js';
// import the server-side part of the `platform-init` plugin
import pluginPlatformInit from '@soundworks/plugin-platform-init/server.js';

Then register it into the server.pluginManager component:

// src/server/index.js
const server = new Server(config);
server.useDefaultApplicationTemplate();
// register the plugin into the soundworks' plugin manager
server.pluginManager.register('platform-init', pluginPlatformInit);

The pluginManager.register method takes at least 2 arguments:

• A user defined id (here platform-init) that is used as an internal identifier to retrieve the plugin instance. In more advanced use-cases, it also allows you to register several times the same plugin under different ids .
• A factory function (i.e. pluginPlatformInit) automatically executed by soundworks, from which the actual plugin instance will be created.

And that's all for the server-side! Let's now install the plugin on the client-side.

Client-side registration ​

Let's open the src/clients/player/index.js and, as for the server-side, import the client-side part of the platform-init plugin:

// src/clients/player/index.js
import { Client } from '@soundworks/core/client.js';
import launcher from '@soundworks/helpers/launcher.js';
// import the client-side part of the `platform-init` plugin
import pluginPlatformInit from '@soundworks/plugin-platform-init/client.js';

Now that our plugin is imported, we can register it into the client.PluginManager:

// src/clients/player/index.js
const client = new Client(config);
// register the plugin into the soundworks' plugin manager
client.pluginManager.register('platform-init', pluginPlatformInit);

As for the server-side, we passed 2 arguments to the client.PluginManager#register method: the plugin user-defined id and the plugin factory function. An important point here is that the id we used is the same on both server-side and client-side. This allows soundworks to automatically match and associate the two components.

At this point, if you start the server (i.e. npm run dev) and go to http://127.0.0.1:8000, you should see the default splash screen provided by the plugin. This screen requires a user gesture (i.e. a "click" event) and is automatically shown by the launcher because the platform-init plugin has been registered into soundworks:

Resuming an AudioContext ​

So far, so good but what we did until now is mainly to add a slash screen asking for a click, that does nothing particular... Or, as stated in the beginning of the tutorial, the whole aim of the platform-init plugin is to simplify the initialization of features that require a user-gesture in order to be properly launched. Let's exemplify that by resuming an AudioContext So let's do that.

So first, let's first create an new audioContext:

// src/clients/player/index.js
const config = window.SOUNDWORKS_CONFIG;
// create a global audio context
const audioContext = new AudioContext();

And pass it as third argument to the pluginManager.register method:

// src/clients/player/index.js
const client = new Client(config);
// register the plugin into the soundworks' plugin manager, and pass it the audioContext
client.pluginManager.register('platform-init', pluginPlatformInit);  
client.pluginManager.register('platform-init', pluginPlatformInit, { audioContext });  

Finally, let's create some welcoming sound that will show us that everything works well and that our audioContext is properly resumed:

// src/clients/player/index.js
launcher.register(client, { initScreensContainer: $container });

// launch application
console.log(`> before start - audioContext is "${audioContext.state}"`);
await client.start();
console.log(`> after start - audioContext is "${audioContext.state}"`);

const now = audioContext.currentTime;
// create a simple envelop
const env = audioContext.createGain();
env.connect(audioContext.destination);
env.gain.setValueAtTime(0, now);
env.gain.linearRampToValueAtTime(0.5, now + 0.01);
env.gain.exponentialRampToValueAtTime(0.0001, now + 4);

const src = audioContext.createOscillator();
src.connect(env);
// randomly pick a frequency on an harmonic  spectrum (150, 300, 450, etc...)
src.frequency.value = 150 + Math.floor(Math.random() * 10) * 150;
src.start(now);
src.stop(now + 4);

Reload the page (Cmd+R) and click, you should now ear an incredibly nice sound coming from your speakers!

Notes on the @soundworks/helpers default views ​

The splash screen, as well as other default initialization views that we have not seen yet, are automatically created and handled the launcher object included in the default application template:

// src/clients/player.index.js
launcher.register(client, { initScreensContainer: $container });

The launcher offer numerous way to adapt these views to your specific needs: e.g. to change the default styles, to adapt the language, or even to use completely different user defined views.

While won't cover these advanced use-case here, as they will be the subject of a dedicated tutorial, let's just see here the minimal changes we can make to customize the init view.

Let's then open the config/application.json file which should look like this:

// config/application.json
{
  name: 'plugin-platform-init',
  author: '',
  clients: {
    player: {
      target: 'browser',
      default: true,
    },
  },
}

This file has been generated for you by the soundworks wizard, and the clients entry is automatically updated each time you create a new client using the wizard.

However, the first 2 lines can be safely updated and are used by the launcher to create the splash screen. Let's just change the name and author entries to see it in action:

name: 'plugin-platform-init', 
name: 'Hello Plugins', 
author: '', 
author: 'me & myself', 

And tada! If you now go to http://127.0.0.1:8000 you should now see something like:

Conclusion ​

In this tutorial, you have learned the basics of soundworks plugins usage, and more precisely how to use the platform-init plugin. While this plugin is not per se very complex, it can save you a lot of (quite boring) development time by simplifying the initialization of certain browser features. Along the way, you also discovered some of the functionalities provided by the launcher component that is automatically included in all soundworks applications created using the wizard.

In the next tutorial, we will wrap up what we have learned so far by creating a small working application where several clients can be used as distributed speakers by a central controller.