Evergreen Legacy Applications

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❤

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Evergreen Legacy Application

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hswolﬀ.com @hswolﬀ

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youtube.com/hswolﬀ

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⚓

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#thoughtleadership

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Rule 1 Have a good reason to do it

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Rule 1: Have a good reason to do it • Why are you even bothering? What are you trying to solve? • Does the state of your current application make it diﬃcult to add more features? • Is it hard for you to recruit because the job market for the tech you use is shrinking? • Make sure you have a good reason for tackling this large tech debt problem before you begin.

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✅

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Rule 2 Don't stop and rewrite everything

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Rule 2: Don't stop and rewrite everything • This is a stop the world solution and one that is rarely a good idea. • It takes a lot of time to get to parity with your existing application. • Hard to rediscover all the edge case bugs that were ﬁxed over years. • Stops work on new functionality. Which can be hugely damaging to a young company. • There are times when it's the right call… • …but those are the exceptions, not the rule.

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Rule 3 Prepare to be in a state of constant migration

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Rule 3: Prepare to be in a state of constant migration • Having an Evergreen Legacy Application means your old code and new code will exist alongside each. Possibly forever. • You have to be ok with living in this hybrid world. • Prepared to take a small cost when switching context between the old and the new. • It's ok to not have an end path to removing legacy code, but you have to be ok with living in a world of ﬂux

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Rule 4 What is new today is legacy tomorrow

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Rule 4: What is new today is legacy tomorrow • Be careful with how many new things you adopt. • Each new thing increases your overall maintenance burden. • Eventually everything becomes legacy.

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Harry’s 4 Rules • Rule 1: Have a good reason to do it • Rule 2: Don't stop and rewrite everything • Rule 3: Prepare to be in a state of constant migration • Rule 4: What is new today is legacy tomorrow

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2009

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2009

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V1: 2009 Server with jQuery

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2014

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V1: 2009 Server with jQuery V2: 2014 SPA w/ Backbone.js

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React

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V1: 2009 Server with jQuery V2: 2014 SPA w/ Backbone.js V3: 2017 SPA w/ React

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Rule 2 Don't stop and rewrite everything Don't stop and rewrite everything

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React + = ♥

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UI Data Styles

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Rule 3 Prepare to be in a state of constant migration

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const FooterView = mixInto(Marionette.View)( onInitialRenderPromise, removeViewOnDestroyMixin ).extend({ className: 'app-footer', template, initialize() { this.onInitialRender.then(() => this.render()); }, });

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const FooterView = mixInto(Marionette.View)( onInitialRenderPromise, removeViewOnDestroyMixin, viewWithReact ).extend({ className: 'app-footer', template, initialize() { this.onInitialRender.then(() => this.render()); this.registerReactComponent( , '.js-react-site-footer' ); },

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registerReactComponent(reactElement, selector) { this._registeredReactMetadata[selector] = { mounted: false, reactElement, selector, }; }, onRender() { Object.keys(this._registeredReactMetadata).forEach(selector => { const reactComponent = this._registeredReactMetadata[selector]; const domElement = this._getElForSelector(reactComponent.selector); ReactDOM.render(reactComponent.reactElement, domElement); }); },

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UI Migration 1.Add viewWithReact mixin 2.Register React Component 3.Proﬁt!

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const person = { name: 'harry', location: 'spain', }; const model = new Backbone.Model(person); model.get('name'); // 'harry' model.set('name');

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class BackboneWrapper extends React.Component { componentDidMount() { this.props.model.on('change', this.handleChange); } componentWillUnmount() { this.props.model.off('change', this.handleChange); } render() { return

{this.props.model.get('text')}

; } }

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import { connectBackboneToReact } from 'connect-backbone-to-react';

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