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

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, just call it player (with the browser target and the default template) so that the rest of the tutorial will be more simple to follow:

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

Then select the install / uninstall soundworks plugins entry:

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

And confirm:

After the installation, 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, that among other things allows you to keep a list the dependencies of your project, you should see the @soundworks/plugin-platform-init appearing under the dependencies key:

// package.json
"dependencies": {
  "@soundworks/core": "^4.0.0-alpha.0",
  "@soundworks/helpers": "^1.0.0-alpha.2",
  "@soundworks/plugin-platform-init": "^1.0.0-alpha.1",
  "json5": "^2.2.2",
  "lit": "^2.2.2"
},

If for some reason 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 the application.

Note that by design, all soundworks plugins always come with both a server-side component and a client-side component. So, 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, and allows to register several time the same plugin under different ids in advanced use-cases.
• A factory function (i.e. pluginPlatformInit) automatically executed by soundworks, that returns the actual plugin instance.

That's all for the server-side, so 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';

// server-side
import pluginPlatformInit from '@soundworks/plugin-platform-init/server.js';
// client-side
import pluginPlatformInit from '@soundworks/plugin-platform-init/client.js';

Now that our plugin is imported, let's also 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. Note that the user-defined id is the same on both server-side and client-side, which allows soundworks to automatically match and associate the two components.

If you start the server now (npm run dev) and go to http://127.0.0.1:8000, you should see the splashscreen that requires a user gesture (i.e. a "click" event) and that is automatically shown due to the fact that the platform-init plugin is registered into soundworks:

Resuming an AudioContext ​

So far, so good but what we did until now is just to add a slashscreen asking for a click that does nothing particular... Or, as we said in the beginning of the tutorial, the whole aim of the plugin is to simplify the initialization of features, such as the Web Audio API AudioContext, that require a user-gesture in order to be properly launched. 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 + 1);

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 + 1);

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 spashscreen (and other init / loading views that we have not seen yet) are not directly provided by the platform-init plugin but rather by the @soundworks/helpers package and more precisely the launcher object included in the default application. Hence, the views are automatically created by the launcher when it registers the soundworks client in the initialization of the application:

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

The launcher offer numerous way to adapt the initialization views to your needs: e.g. change the default styles, adapt the language, or even use completely 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 you 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 splashscreen. 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 certains browser features. Along the way, you also discovered the view 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 connect and be used as distributed speakers by a central controller.