Frontend Architecture for Scalable Design Systems: Design4Drupal 2019

How do you build and manage a design system’s frontend architecture that is both scalable and maintainable?

The typical tools and techniques for approaching design systems often break down when trying to scale across multiple sites, integrate with dynamically injected content, or keep the system up to date. Many of these technical boobytraps aren't discovered till late in development, but can be avoided through progressively decoupled components.

This session is most appropriate for frontend developers & architects or teams building and maintaining a design system. You will learn:

- Why and how to decouple a design system from Pattern Lab and Drupal
- Preventing component fragmentation in Drupal through the use of web components
- Pattern Lab improvements and techniques to reduce rework and ease Twig-based component integration
- How distributing a design system via NPM (yes, NPM) can help teams overcome technical hurdles with Composer

Transcript

1. Frontend Architecture for Scalable Design Systems Tweet me questions! @salem_ghoweri Slides: bit.ly/boltdesignsystem-d4d Design4Drupal 2019
2. How to build a modern, 
 scalable design system? • Maintainable: make it easy to keep code + docs up to date • Flexible: lets developers pick & choose the components to install + update • Easy to Integrate: share Twig templates in Drupal, Symfony, & Pattern Lab • Framework Agnostic: works with Angular, Vue, React, static sites, etc
 
 … in 50 minutes or less.
3. Salem Ghoweri • Twitter @salem_ghoweri • Lead Frontend Architect at Pegasystems (Cambridge, MA) • Building design systems, pattern libraries for over 4 years • Creator and lead developer of the Bolt Design System • Core contributor on the open source Pattern Lab projects (PHP and Node)
5. 3 years ago, the front-end code in our Drupal sites was a bit of a mess…
6. …so we used tools like Pattern Lab to build our first Design System!
7. We used all the best front-end tools & techniques… Tools Generic Elements Settings Objects Components Themes Utils ITCSS Webpack Atomic Design
8. • Built Drupal-friendly Twig-based components in Pattern Lab • Documented our components via markdown + demos in Pattern Lab • Twig namespaces + Components module for tight Drupal integration • “Bleeding edge” approach of having the design system codebase as a separate repository outside of Drupal (pulled in via Composer) …and embraced the best practices for Drupal + PL integration
9. Many of our Drupal sites used our first design system!
10. And everything was perfect. The End.
11. Actually… our first design system started having some problems. …major scalability problems
12. …major scalability problems How do I use this component? 
 What are the different config options? What changed with this most recent release? Reorganizing Pattern Lab’s docs completely broke all these Twig templates in Drupal… Component
 Fragmentation Issues Shipping Code via Composer Fragile
 Integrations We had to recreate this component’s Twig template… forgot to tell you… and now your CSS updates broke Drupal. WHY IS DRUPAL HAVING TO INSTALL PATTERN LAB?! We couldn’t configure this in Drupal so we had to hack something together with some inline styles… We didn’t know that Twig template required that option… We need to build and ship a new component ASAP that looks like the design system… Poor Documentation
13. The fragmentation got so bad… “We need half the pages in Drupal to use the old version of the design system (from a year ago)…
 
 …and the other half needs to use the latest version…” …our first design system was basically dead. ⚰
14. A Scalable Design System Needs To Solve 2 Major Challenges 1. Maintainability: how do you maintain, support, and improve the design system over time? ^ bug fixes, docs, testing coverage, refactors, enhancements, etc
 
 2. Fragmentation: how do you prevent the code that’s been shipped from falling apart over time? ^ easy to upgrade + hard to break + related code stays in sync
15. So we rebuilt.
16. 1. More maintainable docs & demos that stay up to date. 2. More flexible, more encapsulated, and more cross- platform-friendly components. 3. Make the design system’s code installable à la carte. 4. Make integrations as automated as possible. Bolt Design System Goals:
17. Solution #1: 
 API-powered Docs
18. Step 1: Structure your code to be export-friendly // packages/core/styles/…/_settings-colors.scss @import ' ../ ../02-tools/tools-data/tools-data.scss'; $bolt-brand-colors: ( indigo: ( xdark: hsl(233, 71%, 8%), dark: hsl(233, 47%, 16%), base: hsl(233, 47%, 23%), light: hsl(233, 33%, 49%), xlight: hsl(233, 73%, 81%), ), ); @include bolt-export-data('colors/brand.bolt.json', $bolt-brand-colors); { "indigo": { "xdark": "rgb(6, 9, 35)", "dark": "rgb(22, 26, 60)", "base": "rgb(31, 38, 86)", "light": "rgb(84, 93, 166)", "xlight": "rgb(171, 179, 242)" } } Step 2: Export data about your code
19. // BoltCore.php — teach Twig about data in the design system function initRuntime(\Twig_Environment $env) { try { $fullManifestPath = TwigTools\Utils ::resolveTwigPath($env, '@bolt-data/full-manifest.bolt.json'); $dataDir = dirname($fullManifestPath); $this ->data = self ::buildBoltData($dataDir); } catch (\Exception $e) {} } /** * @param $dataDir {string} - Path to data directory * @return {array} - Json files parsed as a single array */ function buildBoltData($dataDir) { ...} // Expose data globally via Twig’s getGlobals API public function getGlobals() { return [ 'bolt' => [ 'data' => $this ->data, ], 'enable_json_schema_validation' => true, ]; } Step 3: Teach your design system to other systems (like Twig)
20. {% for colorName, palette in bolt.data.colors.brand %} {% include "_color-swatch.twig" with { color_swatch: { colorName: colorName, palette: palette } } %} {% endfor %} Step 4: Use It!
22. Solution #2 
 Component Schemas $schema: 'http: //json-schema.org/draft-04/schema#' title: 'Bolt Button' description: 'Buttons are the core of our action components.' type: object required: - text properties: attributes: type: object description: A Drupal-style attributes object for adding extra HTML attributes. text: title: 'Button Text' description: 'The text displayed inside a button' type: string icon: type: object description: Nested icon component. Accepts an extra 'position' prop for placement. ref: '@bolt-components-icon/icon.schema.yml'
23. • Describes your existing data format(s). • Provides clear human—and machine—readable documentation. • Validates data which is super helpful for: ◦ Automated testing ◦ Enforcing rules about the data passed into components ◦ Managing API changes over time What’s a schema? https://json-schema.org/
24. Step 1: Write schemas # button.schema.yml $schema: 'http: //json-schema.org/draft-04/schema#' title: 'Bolt Button' description: 'Buttons are the core of our action components.' type: object required: - text properties: attributes: type: object description: Drupal attributes object text: // package.json "schema": "button.schema.yml"
25. // bolt-button/package.json "schema": "button.schema.yml" // www/build/data/full-manifest.bolt.json { "name": "@bolt/components-button", “basicName": "bolt-components-button", "dir": "/Users/ghows/sites/bolt-release/packages/components/bolt-button", "assets": { "style": "/Users/ghows/sites/bolt-release/packages/components/bolt-button/index.scss", "main": "/Users/ghows/sites/bolt-release/packages/components/bolt-button/index.js" }, "deps": ["@bolt/core"], "twigNamespace": “@bolt-components-button", "schema": { "$schema": "http: //json-schema.org/draft-04/schema#", "title": "Bolt Button", “description": "Buttons are the core of our action components.", "type": "object", "properties": { "attributes": { Step 2: Aggregate the data // bolt-link/package.json "schema": “link.schema.yml"
26. <?php namespace Bolt\TwigExtensions; use BasaltInc\TwigTools; class BoltCore extends \Twig_Extension implements \Twig_Extension_InitRuntimeInterface { public function getFunctions() { return [ TwigTools\TwigFunctions ::get_data(), TwigTools\TwigFunctions ::validate_data_schema(), ], } } // composer.json "require": { "basaltinc/twig-tools": “^1.4.0", } Step 3: Teach other systems about these schemas (like Twig)! • Globally provide schema data • Import schema files directly • Validate data being passed in • Automatically add default data
27. Step 3: Teach other systems about these schemas (or JavaScript)! import schema from ‘ ../link.schema.yml'; @define class BoltLink extends BoltAction { static is = 'bolt-link'; static props = { display: props.string, valign: props.string, url: props.string, target: props.string, isHeadline: props.boolean, }; constructor(self) { self = super(self); self.schema = schema; return self; } render() { // Validate the original prop data passed along // Returns back the validated data w/ defaults adde const { display, valign, url, target, isHeadline } this.validateProps( this.props, ); } • Globally provide schema data • Import schema files directly • Validate data being passed in • Automatically add default data
28. {% set schema = bolt.data.components['@bolt-components-button'].schema %} {% for size in schema.properties.size.enum %} <p>Button Size Variation: {{ size }} </p> {% include "@bolt-components-button/button.twig" with { "size": size, "text": "Example " ~ size ~" Button" } %} {% endfor %} Pattern Lab demos Step 4: Use it to power everything!
29. Component Documentation
30. import { render } from '@bolt/twig-renderer'; const { readYamlFileSync } = require('@bolt/build-tools/utils/yaml'); const { join } = require('path'); const schema = readYamlFileSync(join( __dirname, ' ../button.schema.yml')); const { tag, size } = schema.properties; // test server-side rendering via Twig + rendering service size.enum.forEach(async sizeOption => { test(`button size: ${sizeOption}`, async () => { const renderedTwigTemplate = await render('@bolt-components-button/button.twig', { text: `${sizeOption} Button`, size: sizeOption, }); expect(renderedTwigTemplate.ok).toBe(true); expect(renderedTwigTemplate.html).toMatchSnapshot(); }); }); Schema-powered Jest tests
31. Schema-powered component validation (CLI) $schema: 'http: //json-schema.org/draft-04/ schema#' title: 'Bolt Button' required: ✖ Failed to recompile Pattern Lab! Error with code 1 after running: php: “/Users/ghows/sites/bolt/packages/components/bolt-button/src/button.twig” had schema validation errors: `text` The property text is required {% include "@bolt-components-button/button.twig" with { iconOnly: true, icon: { name: "close" }
32. Schema-powered component validation (in-browser)
33. Schema-powered Component Explorer
34. $schema: 'http: //json-schema.org/draft-04/schema#' title: 'Bolt Button' description: 'Buttons are the core of our action components.' type: object required: - text properties: attributes: type: object description: A Drupal-style attributes object for adding extra HTML attributes. text: title: 'Button Text' description: 'The text displayed inside a button' One Schema To Rule Them All! Component 
 Documentation Configuration 
 Defaults ✅ CLI + In-Browser 
 Validation Component Tests Component 
 Explorer Label Label Pattern Lab 
 Demos
35. Solution #3 
 Twig + Web Components <bolt-button url=“/pattern-lab/index.html”> View The Components </bolt-button> ✨
36. ❖ Web Components are a collection of low level APIs: • Custom Elements: defines the custom HTML tag used by the component (ex. <bolt-button>) • Shadow DOM: encapsulates the HTML and CSS inside a component • HTML Templates: reusable HTML templates • ES6 Modules: import & use components in other components ✤ Web Components bring native components to the web platform. ❖ Many great web component libraries & tools available: • Libraries & Tools: Lit-HTML, SkateJS, Lit-Element, StencilJS • Frameworks: Polymer 3, Ionic Framework, Angular, Preact, React, Vue.js, Svelte… Web Components:
 Components That Work Everywhere!
37. Cross-browser support?
 It’s quite good + polyfills exist for older browsers! https://www.webcomponents.org/
38. import { define, BoltBase, html } from ‘@bolt/core’; import classNames from 'classnames/bind'; import styles from ‘./button.scss'; const cx = classNames.bind(styles); class BoltButton extends BoltBase { static props = { url: props.string, size: props.string, color: props.string, }; render() { const classes = cx('c-bolt-button', { 'c-bolt-button --medium': !this.props.size, [`c-bolt-button --${this.props.size}`]: this.props.size, 'c-bolt-button --primary': !this.props.color, [`c-bolt-button --${this.props.color}`]: this.props.color, }); return html` ${this.addStyles([styles])} <a href=“${this.props.url}” class=“${classes}”> ${this.slot(‘default')} </a> `; } customElements.define('bolt-button', BoltButton); <html> <body> <bolt-button url=“https: // boltdesignsystem.com"> View The Docs </bolt-button> <script src="/build/bolt-global.js" async> </script> </body> </html>
39. {% include "@bolt-components-button/button.twig" with { text: "View The Components", url: "/pattern-lab/index.html", style: "primary" } only %} <bolt-button> via Twig <bolt-button url=“/pattern-lab/index.html"> View The Components </bolt-button> <bolt-button> via HTML import '@bolt/components-button'; render(){ return html` <bolt-button url=“/pattern-lab/index.html"> View The Components </bolt-button> `; } <bolt-button> via JS Same component 
 in Twig, Javascript, and plain HTML
40. Twig Pre-rendered Web Components {% include "@bolt-components-button/button.twig" with { text: "View The Components", url: "/pattern-lab/index.html", width: "full", style: "primary" } only %} button.twig <!— Pre-rendered via Twig —> <bolt-button url=“/pattern-lab/index.html”> <a href="/pattern-lab/index.html" class="c-bolt-button c-bolt-button --medium c-bolt-button --full c-bolt-button --border-radius- regular c-bolt-button --primary c-bolt-button --center" is="shadow-root"> <replace-with-children class="c-bolt-button __item">View The Components </replace-with-children> </a> </bolt-button> Rendered HTML (No JavaScript) <!— post-rendered after JavaScript kicks in —> <bolt-button url=“/pattern-lab/index.html”> View The Components </bolt-button> Rendered HTML (With JavaScript)
41. <style>… </style> <a href="/pattern-lab/index.html" class="c-bolt-button c-bolt-button --center c- bolt-button --primary c-bolt-button --medium c- bolt-button --full c-bolt-button—border-radius- regular"> <span class="c-bolt-button __icon is-empty"> <slot name=“before"> </slot> </span> <span class=“c-bolt-button __item"> <slot> </slot> </span> <span class="c-bolt-button __icon is-empty"> <slot name="after"> </slot> </span> </a> Browser doesn’t support Shadow DOM? No problem! <bolt-button url="/pattern-lab/index.html"> <a href="/pattern-lab/index.html" class="c-bolt-button c-bolt-button --center c-bolt-button --primary c-bolt-button --medium c- bolt-button --full c-bolt-button—border-radius- regular"> <span class="c-bolt-button __icon is-empty"> <slot name=“before"> </slot> </span> <span class=“c-bolt-button __item"> View The Components </span> <span class="c-bolt-button __icon is-empty"> <slot name="after"> </slot> </span> </a> </bolt-button> <bolt-button url=“/pattern-lab/index.html”> ▸#shadow-root (open) View The Components </bolt-button> With Shadow DOM Without Shadow DOM
42. Using Bolt’s 
 Web Components in Vue.js https://github.com/bolt-design-system/bolt/tree/ master/example-integrations/vue
43. Using Bolt’s 
 Web Components in Angular https://github.com/bolt-design-system/bolt/tree/ master/example-integrations/angular
44. Using Bolt’s 
 Web Components in Static HTML https://github.com/bolt-design-system/bolt/tree/ master/example-integrations/static-html
45. Solution #4 
 Progressively Decoupling + 
 Publishing to NPM npm install @bolt/components-button
46. Monorepos
47. • A repository that contains multiple packages or projects. These projects can be related (but don’t have to be). • Many of the most popular JavaScript projects have moved to a monorepo: Babel, Gatsby, Webpack, Vue CLI, Storybook, Jest... • Some of the most popular PHP frameworks like Symfony and Laravel are also monorepos! What is a Monorepo? https://gomonorepo.org/
48. • More maintainable codebase • Simplified, more easily shared, de-duplicated dependencies • Easier to coordinate updates across multiple components • Unified tools / build process for linting code, compiling, testing, deploying, and publishing • Single place to report issues / announce releases • Tests across modules are run together → finds bugs that touch multiple modules easier • One single source of truth for making any changes to the code, demos, or documentation Why Go With A Monorepo?
49. Design system contributors: 
 more unified + maintainable code Design system consumers: 
 only pull in the parts needed
50. + How to Monorepo?
51. # publish packages w/ changes since last publishing $ lerna publish { "lerna": "3.13.1", "npmClient": "yarn", "useWorkspaces": true, "version": “2.3.0", } lerna.json "dependencies": { "lerna": "^3.13.1", }, "workspaces": { "packages": [ "packages /*", "packages/config-presets /*", "docs-site" ] } package.json How to Monorepo?
52. “Downgrading” Pattern Lab 1. Reorganized codebase so components don’t live in Pattern Lab, 
 they are simply demoed in Pattern Lab 2. Avoid using Pattern Labisms in the code being shipped 3. This allows Pattern Lab, our Twig-based static site generator (used for the docs site), Drupal, etc to all integrate the exact same way: Twig.
53. Reorganizing Your 
 Design System Codebase └── packages ├── components
 │ ├── bolt-button │ │ ├── __tests __ │ │ ├── src │ │ │ ├── button.scss │ │ │ ├── button.twig │ │ │ └── button.js │ │ ├── index.js │ │ ├── index.scss │ │ ├── button.schema.yml │ │ └── package.json │ └── bolt-icon/ ├── core ├── core-php ├── config ├── global └── build-tools ├── website │ └── src │ ├── pattern-lab │ │ └── _patterns │ │ ├── 01-visual-styles │ │ ├── 02-components │ │ └── ├── button │ │ └── icon │ └── docs/ │ ├── getting-started.md │ └── coding-standards.md ├── example-integrations/ │ ├── drupal-lab/ │ └── vue/ ├── internal-scripts/ Code that’s published
 (components, build tools, config, shared styles, cross browser polyfills, Twig extensions, etc) “Everything Else” (support code)
 (docs, website code, pattern lab demos, example integrations, deploy scripts, etc)
54. But wait, what about PHP dependencies?! • When publishing, git subtree split to sync PHP deps to READ-ONLY git repos • Web hook updates Packagist
55. Solution #5 
 Integrations composer require 
 bolt-design-system/bolt_connect
56. Design System “A La Carte”:
 Install and use just what you need 1. NPM install only the components you need + build tools for compiling • The Webpack-based build tools in Bolt also generate the data that automatically wires up Twig namespaces & extensions to Drupal 2. Configure the build tools based on how you want things setup in Drupal • Also solves the problem of “installed components” vs “enabled components” 3. Composer require the bolt_connect Drupal module to automatically teach Drupal about Twig namespaces and custom Twig extensions
57. { "name": "pega www_theme", "version": "1.0.0", "scripts": { "build": "bolt build --prod", "start": "bolt start", "watch": "bolt watch" }, "dependencies": { "@bolt/build-tools": "2.3.0", "@bolt/components-action-blocks": "2.3.0", "@bolt/components-background": "2.3.0", "@bolt/components-background-shapes": "2.3.0", "@bolt/components-band": "2.3.0", "@bolt/components-block-list": "2.3.0", "@bolt/components-blockquote": "2.3.0", "@bolt/components-breadcrumb": "2.3.0", • NPM installed components live in the node_modules folder • Even works w/ component dependencies!
58. module.exports = { env: 'drupal', buildDir: './dist/', wwwDir: ' ../ ../ ../', verbosity: 1, components: { global: [ '@bolt/global', '@bolt/components-action-blocks', '@bolt/components-background', '@bolt/components-background-shapes', '@bolt/components-band', '@bolt/components-blockquote', .boltrc.js {% set hero %} {% grid "o-bolt-grid --flex o-bolt-grid --matrix o-bolt-grid --middle" %} {% cell "u-bolt-width-12/12 u-bolt-width-5/12@medium" %} {{ featured_image }} {% endcell %} {% cell "u-bolt-width-12/12 u-bolt-width-7/12@medium" %} {% include "@bolt-components-headline/headline.twig" with { text: article_title, size: "xxxlarge", tag: "h1", } only %} {% include "@bolt-components-list/list.twig" with { display: "inline@small", tag: "div", node --blog.html.twig { "name": "pega www_theme", "version": "1.0.0", "scripts": { "build": "bolt build --prod", "start": "bolt start", "watch": "bolt watch" }, "dependencies": { "@bolt/build-tools": "2.3.0", "@bolt/components-action-blocks": "2.3.0", "@bolt/components-background": "2.3.0", "@bolt/components-background-shapes": "2.3.0", package.json
59. https://github.com/bolt-design-system/bolt/tree/master/example-integrations/drupal-lab
60. Recap
61. 1. Component schemas can provide a powerful way to keep your design system up to date, validated, and well documented. 2. Building Twig-integrated Web Components allow for more resilient, more flexible, more future-proof, and more cross-platform interoperability FTW. 3. Progressively decoupling your design system from Drupal — and Pattern Lab using a monorepo can help better organize, maintain & scale your system. 4. Publishing your design system to NPM allows developers to install and use to use just the components that they need. 5. Automating Twig namespaces and Twig extensions can further reduce frictions with Drupal and with Pattern Lab + address fragility issues with manual approach. Key Takeaways
62. https://github.com/bolt-design-system/bolt
63. Thanks! boltdesignsystem.com bolt-design-system channel on the DrupalTwig Slack