Server and client rendering of single page apps

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How we built a micro-service for Wish List that renders a shared client/server-side single page app and what we've learned along the way.

Source for View Assembler mentioned in the talk on GitHub:
http://github.com/NET-A-PORTER/backbone-assembler

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Server and client rendering of single page apps

  1. 1. WISH LIST server and client rendering of single page apps Thomas Heymann @thomasheymann github.com/cyberthom
  2. 2. WHAT WE’VE BUILT
  3. 3. WISH LIST •  Shopping tool •  Track products •  Receive alerts •  Share lists
  4. 4. GOALS & OBJECTIVES •  Improve UI •  Pull out wish list into separate stack of services •  Update front-end code using modern frameworks and best practices –  Perfect candidate for SPA due to mutability •  Minify duplication which led to inconsistencies
  5. 5. SHARED CONCERNS Server Client USER INTERACTIONS LOGGING MONITORING ROUTING PRESENTATION LOGIC APPLICATION DATA views / layout / templates models / collections / business rules / API calls events / animations SITE FURNITURE ANALYTICS i18n translations / date and currency formatting STYLING
  6. 6. •  Developers get DRY and MV* •  Users get best of both worlds: –  fully rendered pages (instant content) –  responsiveness of SPA •  Business gets SEO •  Everybody’s happy 🌈😃🎉 ENVIRONMENT AGNOSTIC
  7. 7. •  EvenThoughtWorks agrees 👌 TECH RADAR http://www.thoughtworks.com/radar/#/techniques Client and server rendering with same code Increasingly, HTML is rendered not only on the server but also on the client, in the web browser. In many cases this split rendering will remain a necessity but with the growing maturity of JavaScript templating libraries an interesting approach has become viable: client and server rendering with same code. HOLD ASSESS TRIAL ADOPT
  8. 8. ARCHITECTURE & TECH STACK
  9. 9. SYSTEMS OVERVIEW WISHLIST API SITE FURNITURE Aggregation Layer Presentation Layer API MAGAZINE API CATALOGUE Core Services & Storage
  10. 10. TECH STACK SERVER CLIENT node.js IE8+ Express Backbone Router cheerio jQuery Backbone Handlebars require.js App
  11. 11. •  Renders nested views •  Re-attaches views to DOM client-side APP COMPONENTS VIEW ASSEMBLER ROUTER MODEL FACTORY SERIALIZER SYNCER •  Ignores duplicate requests and caches responses •  Injects headers •  Matches URLs and extracts params •  Executes controller logic •  Serializes app data to JSON server-side •  Deserializes app data client-side •  Creates models •  Enforces singletons for data bindings
  12. 12. PAGE REQUEST 1.  Instantiate app 2.  Dispatch route (run controller logic) 3.  Render views 4.  Serialize data (models/collections) 5.  Decorate page with site furniture 6.  Send response SERVER WORKFLOW
  13. 13. PAGE LOAD 1.  Instantiate app 2.  Deserialize data (models/collections) 3.  Setup Backbone routes 4.  Dispatch route (run controller logic) 5.  Re-attach views PAGE NAVIGATION 1.  Dispatch route (run controller logic) 2.  Render views CLIENT WORKFLOW
  14. 14. HANDS ON
  15. 15. module.exports = function(options) {! var options = options || {},! App = options.app,! route = options.route;! ! return function(req, res, next) {! var app = new App({! language: req.params.language,! authToken: req.cookies.sessionid! });! ! app! .dispatch(route, req.params)! .done(function(view) {! var html = view.render().outerHTML(),! bootstrap = JSON.stringify(app.serialize());! res.send(html + '<script>' + bootstrap + '</script>');! })! .fail(next);! };! };! SERVE APP MIDDLEWARE
  16. 16. WISH LIST CONTROLLER route('/wishlist/:id', 'wishlist', function(id) {! var app = this, api = app.wishlistApi;! ! var allWishlists = api.getAllWishlists(),! wishlist = api.getWishlist(id),! allWishlistItems = api.getAllWishlistItems(id);! ! var productList = new ProductListView({! collection: allWishlistItems! }),! navigation = new NavigationView({! model: wishlist,! collection: allWishlists! });! mainView = new MainView({! model: wishlist,! views: {! 'append header': navigation,! 'inner [role=main]': productList! }! });! ! return mainView.ready().then(function() {! return mainView;! });! });!
  17. 17. MAIN TEMPLATE <header>! <h1>{{name}}</h1>! ! {{#if isOwner}}! <button>Manage</button>! {{/if}}! ! {{! Navigation }}! </header>! ! <div role="main">{{! Product List }}</div>!
  18. 18. CLIENT-SIDE BOOTSTRAPPING <header>! <h1>Wish List</h1> <button>Manage</button>! <ul class="navigation">! <li>...</li>! </ul>! </header>! <div role="main">! <ul class=“product-list">! <li>...</li>! </ul>! </div>! ! <script>! var app = new App();! ! app.deserialize({bootstrap});! ! route('/wishlist/:id', 'wishlist', function(id) {! app! .dispatch(route, id)! .done(function(view) {! view.attach('.container');! });! });! Backbone.history.start();! </script>!
  19. 19. VOILA!
  20. 20. WHAT WE’VE LEARNED
  21. 21. •  Lots of code bridging differences between environments and libraries –  Introducing extra abstraction layer •  Routing is different –  Stateless server-side routing (new app instance for each request) –  Stateful client-side routing (holding on to app during page navigation) –  Express vs. Backbone routes (reversed order, paths, params) –  Redirects (302 vs. browser location) –  Serve mobile page based on user agent •  Fetching data is different (XMLHttpRequest vs. node request) COMPLEX PROBLEM
  22. 22. •  Caching is different –  Only ever fetch once per incoming request –  Tab could be left open for days –  Expire and re-fetch resources after x seconds client-side •  Error handling is different (HTTP error codes vs. popups) •  Sending email is borderline COMPLEX PROBLEM
  23. 23. •  Dependency management –  CommonJS runs client-side with browserify –  AMD runs server-side with require.js –  Both work but ideally language level support (ES6 Modules) •  Promises –  Q or jQuery Deferred –  Ideally one standard (ES6 Promises) ES5 IMMATURITY
  24. 24. •  Well known jQuery API for DOM manipulation and traversal •  Easy to pick up •  Can translate Backbone apps directly to the server •  No full blown JSDOM, but still slow CHEERIO
  25. 25. •  Airbnb Rendr –  One stop solution (Rendering, Serialization, Routing) –  Pure string concatenation using templates – Fast on the server –  Client-side rendering trashes and re-renders whole DOM (can cause flicker and performance issues) •  Facebook React –  View rendering library (Bring your own MC) –  Virtual DOM approach: slow on the server but super fast client-side –  Fun fact: Inspired by DOOM III CHEERIO ALTERNATIVES
  26. 26. Rendering comment box with 1000 comments SERVER-SIDE PERFORMANCE •  Very simple HTML – String concatenation will shine even more as markup grows in complexity •  React has the edge over Cheerio – JSX uses precompiled objects so can be heavily optimized byV8 (Cheerio parses strings into trees on runtime) RENDR REACT CHEERIO ~ 110 ms ~ 174 ms ~ 204 ms
  27. 27. •  Load performance means time to content (not response time) –  Server-side DOM is slow but faster than serving empty pages •  Think of it as an enhancement to SPA –  Stateless service can be easily scaled up –  Respond with empty pages if load is too high and render client-side •  Client-side rendering performance equally important •  Decide per use case – In certain situations simple Express.js templating with separate client-side JS might be better approach SO WHAT?
  28. 28. •  YES! 🌟😺✨ •  Joy to develop once hard work is done •  Easy and fast to build rich UI and add new functionality •  But: •  Technique in its infants •  Better frameworks/solutions required WORTH IT?
  29. 29. THANKS!

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