Hands on WebAssembly Horacio Gonzalez @LostInBrittany

Who are we? Introducing myself and introducing OVH OVHcloud

Horacio Gonzalez @LostInBrittany Spaniard lost in Brittany, developer, dreamer and all-around geek Flutter

OVHcloud: A Global Leader 200k Private cloud VMs running 1 Dedicated IaaS Europe 30 Datacenters Own 20Tbps Hosting capacity : 1.3M Physical Servers 360k Servers already deployed Netwok with 35 PoPs

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How is the codelab structured? What are we coding today?

A GitHub repository https://github.com/LostInBrittany/wasm-codelab

Nothing to install Using WebAssembly Explorer and WebAssembly Studio

Only additional tool: a web server Because of the browser security model

Procedure: follow the steps Step by step

But before coding, let’s speak What’s this WebAssembly thing?

Did we say WebAssembly? WASM for the friends…

WebAssembly, what’s that? Let’s try to answer those (and other) questions…

A low-level binary format for the web Not a programming language A compilation target

That runs on a stack-based virtual machine A portable binary format that runs on all modern browsers… but also on NodeJS!

With several key advantages

But above all… WebAssembly is not meant to replace JavaScript

Who is using WebAssembly today? And many more others…

A bit of history Remembering the past to better understand the present

Executing other languages in the browser A long story, with many failures…

2012 - From C to JS: enter emscripten Passing by LLVM pivot

Wait, dude! What’s LLVM? A set of compiler and toolchain technologies

2013 - Generated JS is slow… Let’s use only a strict subset of JS: asm.js Only features adapted to AOT optimization

WebAssembly project Joint effort

Hello W(ASM)orld My first WebAssembly program

Do you remember your 101 C course? A simple HelloWorld in C

We compile it with emscripten

We get a .wasm file… Binary file, in the binary WASM format

We also get a .js file… Wrapping the WASM

And a .html file To quickly execute in the browser our WASM

And in a more Real WorldTM case? A simple process: ● Write or use existing code ○ In C, C++, Rust, Go, AssemblyScript… ● Compile ○ Get a binary .wasm file ● Include ○ The .wasm file into a project ● Instantiate ○ Async JavaScript compiling and instantiating the .wasm binary

I don’t want to install a compiler now… Let’s use WASM Explorer https://mbebenita.github.io/WasmExplorer/

Let’s begin with the a simple function WAT: WebAssembly Text Format Human readable version of the .wasm binary

Download the binary .wasm file Now we need to call it from JS…

Instantiating the WASM 1. Get the .wasm binary file into an array buffer 2. Compile the bytes into a WebAssembly module 3. Instantiate the WebAssembly module

Instantiating the WASM

Loading the squarer function We instantiate the WASM by loading the wrapping JS

Using it! Directly from the browser console (it’s a simple demo…)

You sold us a codelab! Stop speaking and let us code

You can do steps 01 and 02 now Let’s code, mates!

WASM outside the browser Not only for web developers

Run any code on any client… almost Languages compiling to WASM

Includes WAPM The WebAssembly Package Manager

Some use cases What can I do with it?

Tapping into other languages ecosystems Don’t rewrite libs anymore

Replacing problematic JS bits Predictable performance Same peak performance, but less variation

Communicating between JS and WASM Shared memory, functions…

Native WASM types are limited WASM currently has four available types: ● ● ● ● i32: 32-bit integer i64: 64-bit integer f32: 32-bit float f64: 64-bit float Types from languages compiled to WASM are mapped to these types

How can we share data? Using the same data in WASM and JS? Shared linear memory between them!

You can do steps 03 and 04 now Let’s code, mates!

AssemblyScript Writing WASM without learning a new language

TypeScript subset compiled to WASM Why would I want to compile TypeScript to WASM?

Ahead of Time compiled TypeScript More predictable performance

Avoiding the dynamicness of JavaScript More specific integer and floating point types

Objects cannot flow in and out of WASM yet Using a loader to write/read them to/from memory

No direct access to DOM Glue code using exports/imports to/from JavaScript

You can do step 05 now Let’s code, mates!

Future To the infinity and beyond!

WebAssembly Threads Threads on Web Workers with shared linear memory

SIMD

Garbage collector And exception handling

WASI WebAssembly System Interface

WebAssembly ❤ Web Components How to hide the complexity and remove friction

The 3 minutes context What the heck are web component?

Web Components Web standard W3C

Web Components Available in all modern browsers: Firefox, Safari, Chrome

Web Components Create your own HTML tags Encapsulating look and behavior

Web Components Fully interoperable With other web components, with any framework

Web Components CUSTOM ELEMENTS SHADOW DOM TEMPLATES

Custom Element To define your own HTML tag <body> … <script> window.customElements.define(‘my-element’, class extends HTMLElement {…}); </script> <my-element></my-element> </body>

Shadow DOM To encapsulate subtree and style in an element <button>Hello, world!</button> <script> var host = document.querySelector(‘button’); const shadowRoot = host.attachShadow({mode:’open’}); shadowRoot.textContent = ‘こんにちは、影の世界!’; </script>

Template To have clonable document template <template id=”mytemplate”> <img src=”” alt=”great image”> <div class=”comment”></div> </template> var t = document.querySelector(‘#mytemplate’); // Populate the src at runtime. t.content.querySelector(‘img’).src = ‘logo.png’; var clone = document.importNode(t.content, true); document.body.appendChild(clone);

But in fact, it’s just an element… ● ● ● ● Attributes Properties Methods Events

You can do step 06 and 07 now Let’s code, mates!