Server and client rendering of single page apps

WISH LIST server and client rendering of

single page apps

Thomas Heymann @thomasheymann

github.com/cyberthom

WHAT WE’VE BUILT

WISH LIST

•  Shopping tool

•  Track products

•  Receive alerts

•  Share lists

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

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

•  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

•  Even ThoughtWorks 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

ARCHITECTURE & TECH STACK

SYSTEMS OVERVIEW

WISHLIST API

SITE FURNITURE

Aggregation Layer Presentation Layer

API MAGAZINE

API CATALOGUE

Core Services & Storage

TECH STACK

SERVER CLIENT

node.js IE8+

Express Backbone Router

cheerio jQuery

Backbone

Handlebars

require.js

App

•  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

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

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

HANDS ON

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

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; ! }); !}); !

MAIN TEMPLATE

<header> ! <h1>{{name}}</h1> !! {{#if isOwner}} ! <button>Manage</button> ! {{/if}} !! {{! Navigation }} !</header> !!<div role="main">{{! Product List }}</div> !

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> !

VOILA!

WHAT WE’VE LEARNED

•  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

•  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

•  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

•  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

•  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

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 by V8 (Cheerio parses strings into trees on runtime)

RENDR

REACT

CHEERIO

~ 110 ms

~ 174 ms

~ 204 ms

•  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?

•  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?

THANKS!