Frontend Architecture for Scalable Design Systems Tweet me questions! @salem_ghoweri Slides: bit.ly/boltdesignsystem 

Building a progressively decoupled, 
 external design system…. • More maintainable documentation • Individually installable components • Drupal and Pattern Lab friendly + automated Twig integration • Works with other systems (Vue, React, static, etc)
 
 … in 30 minutes or less. 

Salem Ghoweri • Twitter @salem_ghoweri • Lead Frontend Architect at Pegasystems • Building design systems, pattern libraries for over 4+ years • Pattern Lab PHP and Node Lead 

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3 years ago, our Drupal front-end code was a bit of a mess... 

…so we used Pattern Lab 
 to build our first Design System! 

It had a great codebase… Tools Generic Elements Settings Objects Components Themes Utils 

• Code for Twig-based components built & lived in Pattern Lab • Drupal integration w/ Twig namespaces + Components module • Component docs = Pattern Lab demos + mostly static markdown • Design system lived as a standalone Git repo outside of Drupal (pulled in via Composer) And Followed Best Practices for Drupal + Pattern Lab Integration 

So lots of our
 Drupal sites used it! 

Unfortunately, our first design system started having some problems… …major scalability problems 

…major scalability problems How do I use this component? 
 What are the different config options? What changed with this most recent release? How do we pull in just this one component’s updates? Slightly reorganizing Pattern Lab’s docs completely broke all these Twig templates in Drupal… Component
 Fragmentation Problems Shipping via Composer Fragile
 Integrations Why are these component docs out of date?! 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… Our 3rd party service injects hard coded design system components onto the page… We didn’t know that Twig template required that option… Oh we copied over / forked those custom Twig extensions months ago… We need to build and ship a new component ASAP that looks like the design system… Poor Documentation 

The fragmentation got so bad… Half the pages on this Drupal site need to use the old version of the design system (from a year ago)…
 
 …and the other half need to use the latest version… …our first design system was basically dead. ⚰ 

Rebuilding a Design System for Scale 

1. Maintainability: how do you systematically maintain, support, and improve the design system over time? ^ bug fixes, docs, testing coverage, refactors, enhancements, etc
 
 2. Fragmentation: how do you systematically prevent the code that’s shipped from falling apart over time? ^ easy to upgrade + hard to break + related code stays in sync A Scalable Design System Need To Solve Two Big Problems 

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: 

Solution #1: 
 API-powered Docs 

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 

// 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) 

{% for colorName, palette in bolt.data.colors.brand %} {% include "_color-swatch.twig" with { color_swatch: { colorName: colorName, palette: palette } } %} {% endfor %} Step 4: Use It! 

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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' properties: 

• 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/ 

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" 

// 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" 

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 

{% set schema = bolt.data.components['@bolt-components-button'].schema %} {% for size in schema.properties.size.enum %}

Button Size Variation: {{ size }}

{% include "@bolt-components-button/button.twig" with { "size": size, "text": "Example " ~ size ~" Button" } %} {% endfor %} Pattern Lab demos Step 4: Use it to power everything! 

Component Documentation 

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 

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" } 

Schema-powered component validation (in-browser) 

Schema-powered Component Explorer 

$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 

Solution #3 
 Twig + Web Components View The Components ✨ 

4 core technologies to build reusable, native-like components: • Custom Elements: defines a custom HTML tag your component uses • Shadow DOM: encapsulated markup and styling inside a component • HTML Templates: reusable HTML templates • ES6 Modules: import & use components in other components Tons of great options available for using web components: • Libraries & Tools: Lit-HTML, SkateJS, Lit-Element, StencilJS • Frameworks: Polymer 3, Ionic Framework, Angular, Preact, React, Vue.js, Svelte… Web Components: Build Once, Ship Everywhere 

Native browser support? 
 Quite good + polyfills for older browsers. https://www.webcomponents.org/ 

{% include "@bolt-components-button/button.twig" with { text: "View The Components", url: "/pattern-lab/index.html", style: "primary" } only %} via Twig View The Components via HTML import '@bolt/components-button'; render(){ return html` View The Components `; } via JS True
 Component Interoperability 

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 View The Components Rendered HTML (No JavaScript) View The Components Rendered HTML (With JavaScript) 

… No Shadow DOM? No Problem! View The Components ▸#shadow-root (open) View The Components 

https://github.com/bolt-design-system/bolt/tree/ master/example-integrations/vue Want to go headless? 

Solution #4 
 Progressively Decoupling + 
 Publishing to NPM npm install @bolt/components-button 

Monorepos 

• 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/ 

• 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? 

Design system contributors: 
 more unified + maintainable code Design system consumers: 
 only pull in the parts needed 

+ How to Monorepo? 

# 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? 

“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. 

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) 

But wait, what about PHP dependencies?! • When publishing, git subtree split to sync PHP deps to READ-ONLY git repos • Web hook updates Packagist 

Solution #5 
 Integrations composer require 
 bolt-design-system/bolt_connect 

Design System A La Carte 1. NPM install only the components you need + build tools for compiling • These Webpack-based build tools 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 a small Drupal module that teaches Drupal about your components + Twig extensions (bolt_connect) 

{ "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! 

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 

https://github.com/bolt-design-system/bolt/tree/master/example-integrations/drupal-lab 

Recap 

1. Schemas can provide a powerful way to keep your design system up to date, validated, and well documented. 2. 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 can help better organize, maintain & scale your system 4. Publishing / installing your design system a la carte via NPM allows integrators to pick and choose just the parts 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 

https://github.com/bolt-design-system/bolt 

Design System + Pattern Lab BoF April 10th (Today), 2:30 - 3pm
 BoF Room 1 | Exhibit Hall | Level 4 Thanks! Web Components BoF April 11th (Tomorrow), 9 to 9:30am
 BoF Room 1 | Exhibit Hall | Level 4 boltdesignsystem.com