Native Javascript applications with NW.JS Jacopo Daeli Software Engineer Paris, Jun 5th 2015 Best of Web 

Clever.js What am I working on at this moment? It’s a good looking and clever open source framework to help developers build web applications quickly. It's designed to give them a quick and organised way to start developing node.js based web apps with useful modules like Mongoose and Passport pre-bundled and configured. 

What are we going to talk about today? - What it is NW.JS a.k.a NodeWebkit - Implementation details - Uses cases - Debugging - Real example: Stream Booth 

What is it NW.JS? (1) NW.JS is a web app runtime based on Chromium and Node.js. It lets you to call Node.js modules directly from DOM and enables a new way of writing native applications with all Web technologies. It's created and developed in Intel Open Source Technology Center. 

What is it NW.JS? (2) Node-WebKit project changed name in January 2015 to NW.JS. Since it is migrated to io.js for updated V8 engine, which helps a lot for integration with latest Chromium versions, it has been renamed because both parts of the name are irrelevant now. 

What is it NW.JS? (3) It integrates Node.js functions into Chromium App const fs = require('fs'); fs.readdir(…, function(…) { for (let i in files) { document.write(files[i]); } }); Applications bin cores dev etc home Library net private sbin … 

What is it NW.JS? (4) Node.js functions live into the main (renderer) thread. require process global … console documents frames … window object renderer thread 

What is it NW.JS? (5) - It runs on OS X, Windows and Linux (of course) - It is easy for packaging and distribution: O@9L AK FG<=&O=:CAL Ak `j \Xjp ]fi gXZbXg`eg Xe[ [`jki`Ylk`fe @LED(BK >`c\j J\jfliZ\j 9gg app Standalone Executable 

What is it NW.JS? (6) It’s also available on npm. You can run apps like this: # globally $ npm install -g nw $ nw ./my_nwjs_app # locally $ npm install nw $ node_modules/.bin/nw ./my_nwjs_app 

What is it NW.JS? (6) It supports Node.js native and third party modules. Async 

What is it NW.JS? (7) - It is based on Chromium and io.js - It is created and developed at Intel - It is open-sourced at GitHub on Dec’ 7 2011 - Get it at: https://github.com/nwjs/nw.js/ - Prebuilt binaries are available to easy development 

Implementation details - Chromium uses MessagePump* family to support its internal message loop - Node.js uses libuv for message loop - NW.JS merges Node.js and Chromium’s message loop: it implements MessagePumpForUv to use libuv for Chromium’s message loop 

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j_fn k_\ n`e[fnwj kffcYXi' xgfj`k`fey [\]`e\j n`e[fnwj `e`k`Xc gfj`k`fe' x_\`g_ky2 .)), xkffcYXiy 2 ]Xcj\ t, xdX`ey 2 x`e[\o'_kdcy t xdX`ey jg\Z`]`\j `e`k`Xc gXg\ j_fn\[ kf lj\i xn`e[f jkXiklg n`e xn`[k_y [\]`e\ n`e xkffcYX j_fn k_\ n xgfj`k`f n`e[fnwj x_\`g_ky2 .)), xkffcYXiy 2 ]Xcj\ t, xdX`ey 2 x`e[\o'_kdcy t xdX`ey jg\Z`]`\j `e`k`Xc gXg\ j_fn\[ kf lj\i x jkXi x [\]` x j_fn x n`e[ Specifies app’s name Specifies initial app’s page Specifies startup window’s feature 

Use cases: distribution platform for games - It supports most HTML 5 features - It’s GPU accelerated - It supports WebGL - Video and audio support 

Use cases: File explorer and file editor - You can choose between Node’s fs module or HTML5 API - You can invoke file select dialogs in JS - Direct dragging files into the window is supported 

Use cases: Media applications - It supports getUserMedia - Audio recording and camera capturing are enabled - and tag are supported: it can play ogg and web formats 

Use cases: PopCorn Time (R.I.P) 

Use cases: PopCorn Time (R.I.P) { "name": "Popcorn-Time", "homepage": "https://popcorntime.io", "repository": { "type": "git", "url": "https://git.popcorntime.io/popcorntime/desktop.git" }, "license": "GPL-3.0", "main": "app://host/src/app/index.html", "version": "0.3.7-2", "node-remote": "client.vpn.ht", "releaseName": "The car wont start", "scripts": { "postinstall": "node_modules/.bin/bower install && grunt setup", "postupdate": "node_modules/.bin/bower update && grunt setup", "test": "grunt --verbose" }, "window": { "title": "Popcorn Time", "icon": "src/app/images/icon.png", "toolbar": false, "frame": false, "min_width": 960, "min_height": 520, "resizable": true, "show": false, "position": "center" }, "dependencies": { "async": "0.9.0", "i18n": "0.5.0", "q": "2.0.2", "read-torrent": "1.0.0", "readdirp": "*", "request": "^2.36.0" … }, … } Manifest file (package.json): 

Use cases: PopCorn Time (R.I.P) if (gui.App.fullArgv.indexOf('--reset') !== -1) { var data_path = require('nw.gui').App.dataPath; localStorage.clear(); fs.unlinkSync(path.join(data_path, 'data/watched.db'), function (err) { if (err) { throw err; } }); fs.unlinkSync(path.join(data_path, 'data/movies.db'), function (err) { if (err) { throw err; } }); fs.unlinkSync(path.join(data_path, 'data/bookmarks.db'), function (err) { if (err) { throw err; } }); fs.unlinkSync(path.join(data_path, 'data/shows.db'), function (err) { if (err) { throw err; } }); fs.unlinkSync(path.join(data_path, 'data/settings.db'), function (err) { if (err) { throw err; } }); } // Global App skeleton for backbone var App = new Backbone.Marionette.Application(); _.extend(App, { Controller: {}, View: {}, Model: {}, Page: {}, Scrapers: {}, Providers: {}, Localization: {} }); Extract of app.js file 

Use cases: PopCorn Time (R.I.P) function Cache(table) { var self = this; this.table = table; var db = indexedDB.open(App.Config.cachev2.name, App.Config.cachev2.version); db.onsuccess = function () { self.db = this.result; }; db.onupgradeneeded = function () { var self = this; App.Config.cachev2.tables.forEach(function (tableName) { if (_.contains(self.result.objectStoreNames, tableName)) { return; } self.result.createObjectStore(tableName, { keyPath: '_id' }); }); }; this._openPromise = WrapRequest(db).promise; } Cache.prototype.set = function (key, value, options) { options = options || {}; var data = _.extend(value, { _id: key, _ttl: options.ttl || 14400000, _lastModified: +new Date() }); return WrapRequest(this.db.transaction(this.table, 'readwrite').objectStore(this.table).put(data)).promise; }; Extract of Cache class 

Debugging (with devtools) // Add this to your manifest file, then you can // open devtools from the devtools button in the toolbar. { "window": { "toolbar": true } } // or you may open devtools programmatically require('nw.gui').Window.get().showDevTools() // Alternatively you can even use the --remote-debugging-port=port // command parameter to specify which port the devtools should listen to // For example, by running nw --remote-debugging-port=9222, you can // open http://localhost:9222/ to visit the debugger remotely. Open dev tools 

Real Example: Stream Booth - Fork it on GitHub: https://github.com/JacopoDaeli/bestof-web-paris-2015 - It streams from the webcam to other devices in the same LAN. - It uses express for serving the webapp files to the audience’s devices - NW.JS app and the webapp exchange messages using socket.io - It uses getUserMedia API for reading from the user webcam - It uses an hidden canvas for getting a video frame each 33ms, converting it into a base64 URL and sending it to the audience. NOW THERE IS A LIVE DEMONSTRATION :-)