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Modernisa0on of legacy PHP applica0ons using Symfony2 23/11/2012 1 THEODO

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The need for progressive rewrite The technical challenges and our solu0ons The future 23/11/2012 2 THEODO

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Legacy PHP applica9ons are everywhere History of PHP applica9ons • 79% : websites wriBen in PHP among the top 1 million, according to W3Techs.com • 1994: PHP was created. Start of the SpageBhi age • 2004: PHP5 was released • 2007: ZF 1.0.0 and SF 1.0 were released. Start of the MVC age 13 years of (mostly) spageBhi-­‐coded web-­‐apps 23/11/2012 3 THEODO

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How do these applica9ons cope with evolu9ons? The need for rewrite • Many businesses rely on web apps wriBen during the spageBhi age • Making legacy applica0ons evolve in a « fast » way becomes impossible. This threatens the businesses that rely on them. Before the big used to eat the small, nowadays it is the fast who eat the slow • What they lack is a well-­‐designed decoupled and tested architecture that would bring flexibility of evolu0on. 23/11/2012 4 THEODO

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Star9ng a new version from scratch is a danger to the business The dangers of total rewrite • New developments are invisible un0l the new version is finished • You need twice more developers: one team to maintain the old applica0on, while the second team is wri0ng the new version • The probability of forge]ng features during the rewrite is high • Transi0on when the new version is ready becomes costly and very dangerous: everything is impacted at once 23/11/2012 5 THEODO

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Progressive rewrite is the solu9on… but is very challenging The challenge of progressive rewrite • You have to work with hard-­‐to-­‐read code • All the aspects of an applica0on in produc0on are concerned: Ø source code of course Ø system Ø data Ø cache Ø remote webservices, etc. • The major conceptual challenge in all those aspects is decoupling of modules. Just like in scaling! 23/11/2012 6 THEODO

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Progressive rewrite is more profitable Unbeatable 9me-­‐to-­‐market Functionalities Functionalities Evolu9on Time Time • No new features for months • Only 1 app to maintain • 2 apps to maintain • Lower regression risks • Unbeatable time-to-market 23/11/2012 7 THEODO

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The need for progressive rewrite The technical challenges and our solu0ons The future 23/11/2012 8 THEODO

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Theodo Evolu9on Our solu9on at Theodo • R&D project started at Theodo in 2012 • Aims to solve all these issues to make app rewri0ng agile again • And help Symfony2 take over the world! 23/11/2012 9 THEODO

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The technical experts behind Theodo Evolu9on Theodo Evolu9on team 23/11/2012 10 THEODO

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The big picture of the different technical aspects to solve The technical challenges • Preven0ng regressions • Upgrading the system • Rou0ng • Sharing the layout • Sharing the session/authen0ca0on • Decoupling the code • Migra0ng the model and data 23/11/2012 11 THEODO

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Preven0ng regressions 23/11/2012 12 THEODO

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Belt and straps are necessary… and won’t be enough… Preven9ng regressions 23/11/2012 13 THEODO

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Func9onnaly test what could harm your business Preven9ng regressions • By defini0on, spaghe] code is deeply coupled. Touching one part breaks something at the other end • Create func0onal tests on the most cri0cal scenarios • Mink + ZombieJS: hBps://github.com/Behat/Mink 23/11/2012 14 THEODO

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Setup external monitoring and a fast deployment pipeline Preven9ng regressions The most thorough func0onal tes0ng is done... by pu]ng in produc0on! • Monitor produc0on well • Deploy ohen and small updates • Setup a fast rollback system • Setup a fast deployment system, because you want to make it faster to correct small problems than to rollback 23/11/2012 15 THEODO

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Upgrading the system 23/11/2012 16 THEODO

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Migrate to a modern environment that supports Symfony2 …and improves performance as a bonus. Upgrading the system • Symfony2 requires: • PHP 5.3.3 • Sqlite3, JSON, ctype • date.0mezone set in php.ini • php app/check.php 23/11/2012 17 THEODO

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Check that the legacy code will support PHP 5.3/5.4 Upgrading the system • Phpcs CodeSniffs for 5.3 and 5.4 compa0bility: hBps://github.com/wimg/PHPCompa0bility • Setup a pre-­‐produc0on environment in the upgraded environment and run your func0onal tests on it • And this 0me provision your environment with Puppet or Chef! Check Blueprint: hBps://github.com/devstructure/blueprint 23/11/2012 18 THEODO

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Rou0ng 23/11/2012 19 THEODO

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Rou9ng between the old and the new Rou9ng • The beauty of PHP: some legacy apps have simply no rou0ng system! • Host the new app next to the old app, with clear URL differences, and proxy at the server level • Subdomain: v2.myapp.com • Subfolder: www.myapp.com/v2/ • My favourite: create a catchall route with Symfony2 23/11/2012 20 THEODO

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The CatchAll Route Rou9ng class LegacyController extends Controller! {! /**! * @Route("/{filename}.php", name="_proxy")! */! public function proxyAction($filename)! {! ob_start();! include $filename . .php;! ! return new Response(ob_get_clean());! }! }! 23/11/2012 21 THEODO

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Rou9ng from the new to the legacy Rou9ng • If you have a rou0ng system in the legacy, you need to boot it • For Symfony1, create a twig extension to use « url_for » in your new templates • Don’t forget: sfConfig::set(sf_no_script_name, true); 23/11/2012 22 THEODO

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Sharing the layout 23/11/2012 23 THEODO

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For end-­‐users « progressive rewrite » = « same template » Sharing the layout • Copy-­‐pas0ng the layout is not a good solu0on • Our solu0on : crawl the legacy layout and include it as ESIs ! <esi:include src="{{ path(legacylayout_top) }}" />! ! {% block body %}{% endblock %}! ! <esi:include src="{{ path(legacylayout_bottom) }}" />! ! 23/11/2012 24 THEODO

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The « crawling » part of the ESI sub-­‐request Sharing the layout ! $this->client->setHeader(Cookie, $currentCookie); if ($request->headers->has(authorization)) { $this->client->setHeader( Authorization, $request->headers->get(authorization) ); } if ($this->session->isStarted()) { $this->session->save(); } $this->client->request(GET, $url); $esiContent = $this->client->getResponse()->getContent(); 23/11/2012 25 THEODO

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Sharing the session/authen0ca0on 23/11/2012 26 THEODO

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Make the legacy session accessible from Symfony2 Sharing the session/authen9ca9on • You want to access what your legacy app has put in the session from within Symfony2… • BUT Symfony2 expects session informa0on to be neatly stored in arrays in the « _sf2_aBributes » namespace to make your legacy session accessible, you need to : • register « Bags » for each of your legacy $_SESSION keys • create a « ScalarBag » type when these values are not arrays 23/11/2012 27 THEODO

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Example for a Symfony1 Session Sharing the session/authen9ca9on // onKernelRequest!foreach ( array(symfony/user/sfUser/credentials,! !symfony/user/sfUser/attributes’) as $namespace){! $bag = new NamespacedAttributeBag($namespace, .); $bag->setName($namespace);! $session->registerBag($bag);!}! 23/11/2012 28 THEODO

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Integra9ng 9ghtly sf1 and Sf2 authen9ca9on systems Sharing the session/authen9ca9on We have created a great bundle for that! 23/11/2012 29 THEODO

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Decoupling the code 23/11/2012 30 THEODO

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A^acking the spaghe_ problem Decoupling the code 23/11/2012 31 THEODO

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Decoupling is a major aspect of progressive rewrite Decoupling the code 23/11/2012 32 THEODO

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Decoupling is a major aspect of progressive rewrite Decoupling the code 23/11/2012 33 THEODO

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Decoupling is a major aspect of progressive rewrite Decoupling the code 23/11/2012 34 THEODO

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Decoupling is a major aspect of progressive rewrite Decoupling the code 23/11/2012 35 THEODO

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Decoupling is a major aspect of progressive rewrite Decoupling the code 23/11/2012 36 THEODO

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Decoupling is a major aspect of progressive rewrite Decoupling the code 23/11/2012 37 THEODO

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The dream architecture Decoupling the code 23/11/2012 38 THEODO

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What you usually find Decoupling the code 23/11/2012 39 THEODO

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You need to create the dream API and slowly refactor around it Decoupling the code A A P P I A I P I A P I A P I A A P P I I 23/11/2012 40 THEODO

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You need to create the dream API and slowly refactor around it Decoupling the code A A P P I A I P I A P I A P I A A P P I I 23/11/2012 41 THEODO

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You need to create the dream API and slowly refactor around it Decoupling the code A A P P I A I P I A P I A P I A A P P I I 23/11/2012 42 THEODO

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You need to create the dream API and slowly refactor around it Decoupling the code A A P P I A I P I A P I A P I A A P P I I 23/11/2012 43 THEODO

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This is called « Facade Pa^ern » Decoupling the code Wikipedia A facade is an object that provides a simplified interface to a larger body of code, such as a class library. A facade can: • make a sohware library easier to use, understand and test, since the facade has convenient methods for common tasks; • make the library more readable, for the same reason; • reduce dependencies of outside code on the inner workings of a library, since most code uses the facade, thus allowing more flexibility in developing the system; • wrap a poorly designed collec0on of APIs with a single well-­‐ designed API (as per task needs). 23/11/2012 44 THEODO

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Symfony2 Service Container Decoupling the code • With Symfony2, the new API of the Facade PaBern is a service • Create a bundle for every « module » you iden0fied. • Create a service for every bundle you now have, that will serve as your Facade API • … and start using these services! 23/11/2012 45 THEODO

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Migra0ng the model and data 23/11/2012 46 THEODO

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A typical MySQL database is highly coupled Migra9ng the model and data 23/11/2012 47 THEODO

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Decoupling a rela9onal DB is like a^acking a giant monster Migra9ng the model and data 23/11/2012 48 THEODO

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The classical solu9on is syncing two versions of the data Migra9ng the model and data • Syncing can be done with ETL tools like KeBle or with custom code in the new applica0on • To avoid unbearable headaches, it is highly recommended to write in only one DB. Which means to rewrite parts of the legacy code to save, update and delete in the new DB 23/11/2012 49 THEODO

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A « bearable headache » solu9on: Migra9ng the model and data Legacy Applica0on New applica0on Rou0ng 23/11/2012 50 THEODO

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A « bearable headache » solu9on: Migra9ng the model and data Legacy Applica0on New applica0on Rou0ng 23/11/2012 51 THEODO

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MongoDB and DoctrineODM make it (a li^le) easier Migra9ng the model and data • Remember: progressive rewrite relies on decoupling, just like scaling. Non-­‐rela0onal DBs make par0al evolu0ons easier in the long-­‐term • In a document DB like MongoDB you can have in the same collec0on data which coexist in different versions. • To migrate them « just in 0me » use /** @MongoDBPreLoad */ from the Doctrine ODM 23/11/2012 52 THEODO

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The need for progressive rewrite The technical challenges and our solu0ons The future 23/11/2012 53 THEODO

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The evolu9on of Theodo Evolu9on Theodo Evolu9on strategy • The Theodo team is today 18 and growing excellent web devs working currently on 6 progressive rewrites of huge applica0ons to Symfony2 • Every technical solu0on for progressive rewrite to Symfony2 is bundled in our project Theodo Evolu0on • The goal: make it an out-­‐of-­‐the-­‐box solu0on to work on legacy apps without touching legacy code • And that way convert the whole PHP world to Symfony2 23/11/2012 54 THEODO

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How you can profit from Theodo Evolu9on? Theodo Evolu9on strategy • Some Theodo Evolu0on bundles will be open-­‐ sourced! • Use our massive presence here today! Please ask ques0ons to the guys with the black Theodo hoodies! • Contact us @theodo or fabriceb@theodo.fr 23/11/2012 55 THEODO

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Questions ? fabriceb@theodo.fr @theodo www.theodo.frFeedback: https://joind.in/7569 23/11/2012 56 THEODO