How does http2 change the game of module bundlers?

@yaprakaya

Who am I?

Yaprak Ayazoglu

Frontend developer

@yaprakaya

  • Working @bol.com
  • M.S. in Computer Science
  • B.S. in Electrical and Electronics Engineering
  • Involved in building 1 solar powered and 1 hydrogen powered car
  • Mentoring @LoncaWorks

 

@yaprakaya

@yaprakaya

A bit of history...

  • Tim Berners Lee and his team introduced HTTP protocol in 1989 at Cern
  • HTTP only had "GET" request
  • Reponse was only HTTP page with plain text
  • HTTP1.1 standard was there and also implemented by most of the major browsers in 1996
  • The protocol is not changed since 1997.

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Examples websites from 1996

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Example websites from 1996

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How did it evolve?

  • A single JS file, a tiny CSS, some images
  • More images, we had image sprites: a bundle for the images
  • With SPAs, more JS and CSS files, we needed to bundle them into 1 huge file, too.

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Why bundles?

@yaprakaya

  • Was it a must? What was the problem? 
  • We have more files..
  • >20 images
  • >5 JS files
  • >5 CSS files
  • Why can't we just download them one by one?

@yaprakaya

HTTP/1.1 is sequential

How do we solve it?

  • First approach is bundling... But does bundling enough?
  • Browsers allow 6 parallel connections / domain
  • Domain sharding
  • Image spriting which is also a sort of bundle for your CSS

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Is bundling only for first load time?

  • Not really...
  • It is also for maintainability, structure, clean code..

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Lets go back to 1997

  • Not much of CSS, JS or images required.
  • Just a couple of them would be enough.
  • The recent developments in JS was pushing the boundaries of WEB and thus the HTTP protocol.
  • Browsers were not supporting any native module structure. 
  • We created scopes, IFFE functions (Immediately invoked function expression)

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RequireJS (AMD)

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  • Nice way to create components
  • Asynchronous (not downloading but while running the code)
// define with module ID, dep. array and factory function
define('myModule', ['dep1', 'dep2'], 
function (dep1, dep2) {
   //Define the module value by returning a value.
    return function () {};
});

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Browserify, Webpack (CommonJS)

  • Bundling modules in CommonJS format
  • Creating 1 big JS file

 // ***** lib.js *****
 module.exports = function(n) { console.log(n); }

 // ***** main.js *****
var myLib = require('./lib');
console.log(myLib(5)); // 5

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Rollup, System JS, Webpack, you name it (ES6 Modules)

  • Bundling modules in ES6
// ***** lib1.js *****
export default function() {
console.log(4);
};

// ***** someClass.js *****
export default class {
…
};

 // ***** main.js *****
var myLib = require('./lib');
console.log(myLib(5)); // 5

// ***** main.js *****

import func from ‘./lib1’;
func();

import someClass = require(‘./someClass’);
let myClass = someClass();

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Native Modules

<script type="module">
  import {addTextToBody} from './utils.mjs';

  addTextToBody('Modules are cool. <3');
</script>
// utils.mjs
export function addTextToBody(text) {
  const div = document.createElement('div');
  div.textContent = text;
  document.body.appendChild(div);
}

Time to change

  • More files
  • It was not enough...

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HTTP/2

  • HTTP/1.1 is for web 2 decades ago
  • HTTP2 come into play
  • It supports response multiplexing
  • 1 request has n responses
  • No need to send headers for each request
  • Server push

Now...

  • HTTP/2 is supported for whole major browsers
  • It is backward compatible
  • HTTPS is a must
  • (ES6) Native modules are supported by most of the major browsers (but IE11)
  • Do we need the module bundlers at all?

@yaprakaya

It depends :D

  • Legacy (several non-native modules)
  • Backend systems should be updated
  • Bad caching
  • Good compression
  • How to prioritize the assets?
  • CDNs?
  • Server push
  • Physical location of servers & your users

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Benchmark results


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1000 files to 50 increases speed by an average of ~66%

Benchmark results

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1000 files to 50 increases speed by an average of ~28%

Benchmark results

@yaprakaya

1000 files to 50 increases speed by an average of ~27%

Key findings

  • This benchmark does not involve server push
  • Even though bundling is NOT that big problem with HTTP/2, a certain level of concatenation is an improvement
  • Important to define the requirements since the distance increases the latency

Wrap up...

  • The best practices in HTTP/1.1 is now anti patterns (domain sharding, bundling)
  • Still we need bundling
  • More bundles might cause less compression
  • HTTP/2 will trigger new changes: e.g. new breed of CDNs, push efficient module loading, etc.

Resources

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Questions?

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Thanks...

@yaprakaya

http2 and module bundlers

By Yaprak Ayazoglu

http2 and module bundlers

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