LessonslearnedatYahoo!

DustinWhittleYahoo!

Acasestudyonusingopensourcetoolstobuildaplatformforenterprisewebapplicationsusingsymfony.

Overview

‣  HowdidYahoo!buildYahoo!Bookmarks,Yahoo!Widgets,Yahoo!Answers,andDeliciouswiththesymfonyproject?

‣  Whatisascalablearchitecture?

‣  Howtoworkwithopensourceframeworksintheenterprise?

‣  Whatworkedandwhatdidnotwhenbuildingalargeweb2.0productfromopensourcetools?

‣  Q&A?

‣  symfony‐project.com|developer.yahoo.com

WhoamI?‣  Workingwithsymfonysinceopensource

‣  symfonyCoreTeamMember

‣  ResponsibleforthedevelopmentandsupportofsymfonyatYahoo!

‣  WorkedwithY!Answers,Delicious,Y!Widgets,Y!Bookmarks,Yahoo!ApplicationPlatform

‣  Consultant‣  Commercialsymfonysupport+training(USA)

AlookattheopensourceYahoo!‣  Yahoo!isbuiltfromopensourcetoolsandcommunities

‣  FreeBSD,Linux,Apache,PHP,MySQL

‣  Wecontributebackandeveryonewins

‣  Weshareourtools,experience,anddatathroughopenAPIsandwebservices

‣  Yahoo!UserInterfaceLibraries+EdgeCaching‣  UserInterfaceDesignPatterns‣  ExceptionalPerformanceRules+YSlow

‣  R3I18n+Template+TranslationManagement

AlookatYahoo!Answers‣  http://answers.yahoo.com

‣  Yahoo!AnswersisthelargestcollectionofhumanknowledgeontheWebwithmorethan135millionusersand515millionanswersworldwide(Yahoo!InternalData,March2008).

‣  Yahoo!Answersisthe2ndrankededucation&referencesiteontheweb(comScore)

‣  Availablein26marketsand12languages

Yahoo!Answersatthebeginning‣  StartedasasmalldevelopmentteamonPHP4fromaforkof

Yahoo!TaiwanKnowledge+

‣  LaunchedDecember2005byDecember2006therewere60millionusersand65millionanswers

‣  Thecodebaseeventuallybecamedifficulttomaintainanditeratenewfeatures

‣  Largedistributeddevelopmentteams(US/UK)

Whyafrontendpresentationplatform?‣  Rasmussays“frameworksarenotwellsuitedforY!”

‣  Buildapplicationstorequirements

‣  Doexactlywhatyouneed:nomore,noless

‣  Understandthatframeworksaddalotofoverhead

‣  Despitechoosingopensourceorbuildingyourown‣  Everyoneusesaframework

‣  Ifyouuseopensource,useonlythepiecesyouneed

Thechoicetouseaframework‣  symfonywasinvestigatedforuseonYahoo!Bookmarksasa

testforthelaterre‐architectureofYahoo!Answers

‣  InvestigationwasperformedinFebruary2006

‣  symfony,CakePHP,Prado,ZendFramework,Struts,Tapestry,Spring,Seaside,RubyonRails,Django

‣  PHPhasmostsupportinternally,sothechoicewasreallybetweensymfony,CakePHP,Prado,php.MVC,andZendFramework

Whatdidweneedfromafrontendplatform?‣  Fitexistingenvironment(BSD/PHP5/Apache)forphased

migration

‣  DevelopmentCycle–Howeasytodevelop,test,anddeploy?

‣  Cleanseparationbetweendata,logic,anddisplay(MVC)

‣  Independentmodellayertofitserviceorientedarchitecture

‣  Extensibleandpluggable‣  Internationalizationandlocalizationsupport‣  Detaileddocumentationandactivecommunityofsupport

‣  Opensourceandabilitytocontributeback

Howweusesymfony‣  FrontendProductionSites‣  Yahoo!Answers‣  Delicious‣  Yahoo!Bookmarks

‣  Yahoo!Widgets

‣  Yahoo!ApplicationPlatform

‣  InternalTools‣  CorporateReporting+MiscManagement

‣  WebServices

Thechoicetousesymfony‣  Configurability/Flexibility‣  Featureswedonotwantareeasilydisabled‣  Useoffactoriesforeasycustomization

‣  Documentation/SupportCommunity

‣  TheDefinitiveGuidetosymfony(freeonline)

‣  Excellenttutorialsandexampleapplications‐Askeet

‣  Activecommunitywithwiki,mailinglists,forums,ircchannel

Thechoicetoadoptsymfony?‣  Philosophy

‣  Full‐stackframeworkforbuildingcomplexwebapplications

‣  Adoptbestideasfromanywhere,usingexistingcodeifavailable(Mojavi,Prado,Rails,Django)

‣  Design

‣  CleanseparationbetweenModel,View,andController

‣  Controllerusingmodulesandactions

‣  ViewsusingtemplatesinstraightPHPwithhelpers

‣  Easytoreuseviewmodulestocomposeapage

‣  Layouts,Components,Partials,Slots

symfonyinfeatures‣  MVCDesign+Project/ApplicationStructure

‣  CascadingConfigurationSystem(YAML‐>PHP)

‣  Environments–Dev,Prod,Test,QA,Staging

‣  Flexibleviewlayer–layouts,partials,components

‣  TaskSystem–Taskssystemforprojectmanagement

‣  Internationalization+LocalizationSupport

‣  Form/Widget/ValidationSystem

‣  Security–CSRF+XSSProtection+UserManagement

‣  Caching–APC,Memcache,File,Database

‣  TestingFramework–LIMEUnit+FunctionalTesting

symfonyMVCframework

Acompletefrontendplatform‣  Acommunitymaintainedapproachtobuildingweb

applicationsfromframeworks

‣  PHPFramework

‣  JavaScriptFramework(YUI)

‣  CSSFramework(YUI)

‣  UIDesignPatterns+BestPractices‣  DevelopmentTools(logger,profiler,debugger,docs)

‣  Unit+FunctionalTestingFrameworks(LIME/YUITest)

‣  DeploymentTools(packagedeploymentsystem)

Users

LoadBalancers

Frontend

PHPAPC,PEAR,PECL,CustomExtensions

FreeBSD4.x/6.x,Linux2.6.x

symfony/YUIApacheCustomModules

Backend

MySQL/Oracle WebServices AdAPI UserAPI

Y!HighLevel

Whatdoesitmeantoscale?‣  Asystemwhoseperformanceimprovesafteraddinghardware,

proportionallytothecapacityadded,issaidtobeascalablesystem.

‣  HighAvailability+Scalability+Performance‣  Biggerdataset,moretraffic,maintainable

‣  Notaboutperformance

‣  PHPisslow,butitisnotyourbottleneck

‣  Languagesdonotscale,architecturesdo.

‣  Planningtogrowandplanningtofail

‣  CapacityPlanning‣  BusinessContinuityPlanning

Scaling–Planning‣  Planninghardwarepurchasesandhostingoptionstohaveas

muchasyouneedwithoutbreakingyourwallet

‣  Partitioninganddistributingdatabasestosupportlargedatasetsandsimultaneoustransactions

‣  Monitoringyourapplicationstofindandclearbottlenecks

‣  ProvidingservicesAPIsandusingservicesfromotherproviderstoincreaseyoursite'sreachandcapabilities

‣  ThinkMinimal,Plantogrow,Plantofail.

Scaling–ThebasicsinPHP‣  PHPisrarelythebottleneck‣  “Mostperformancecomesnotfromthelanguage,butfromapplicationdesign”‐

Rasmus‣  ShareNothingArchitecture‣  Independent,self‐sufficient,nosinglepointofcontention‣  Nolocalstorage=NoPHPSessions‣  Useadatabase(worksfordistributed)‣  Useasmallsignedcookie(ideal)‣  Importantdataindatabase‣  Individualexpirationonsessionobjects‣  Smalldataitems

‣  Useadistributedcache‣  Memcache

‣  Forgetaboutsmallefficiencies‐‐Prematureoptimizationistherootofallevil.

PropelorDoctrineor???‣  NoORMforlargeprojects

‣  PropelorDoctrineforlargeprojects‣  Propelforinternalprojects(bestsupported)‣  ExploringDoctrineforthefuture

‣  ServiceOrientedArchitecture‣  Platformsasservices(reusabletoall)

‣  Noheavylifting,pushdownthestack‣  ThinController/FatModel(wheremodel==services)

‣  Java/C++/Erlang+JSON/XML

ScalingDatabases–Thebasics‣  Master/SlaveReplication

‣  Firststeps‣  Helpswithreads,writesarestillbottleneck

‣  Partitioning‣  Segmentingdata

‣  Sharding(horizontalpartitioning)‣  Segmentingdataontodifferentphysicalmachines

‣  Makeproblemssmaller,easiertogrow

ImprovinglatencywithCaching‣  AlwaysusePHPopcodecache(APC,Xcache,etc)‣  Useforroutingandi18ncache

‣  Memcache(distributedcache)‣  Useforviewcache‣  Distributedinvalidationcanbeapain‣  sfViewCacheManagermakesthiseasy!‣  Beintelligentaboutcache_keys(uri,user,state)

‣  Thereisafinelinetocaching‣  Atwhatpointdoyouspendmoretimemanagingthe

cache,thanreadingfromit?

TweakingPerformance‣  Don’tusefeaturesyoudonotneed‣  settings.yml/factories.yml

‣  Usecore_compile(aggregateclasses)‣  Removedebugstatements(sfOptimizerPlugin)‣  Donotuse.htaccess(movetorealapacheconfig)‣  Setaminimalincludepath‣  Increaserealpath_cache_size+realpath_cache_ttl‣  Useapc.stat=0‣  Use@routeName‣  Donotusecomponentsinloop

WhatdoesYahoo!change?‣  Minorchangestofitourenvironment(bsd/php/apache)

‣  Mostofourchangesareeasilyimplementedviafactories

‣  User,Request,Response,I18ncontroller‣  DroppedtheORMandpusheddownthestack(SOA)

‣  AddedaparallelAPIDispatcher(ysfAPIClientPlugin)‣  Addeddimensionstoconfigurations(ysfDimensionsPlugin)

‣  IntegrateR3translation/templatemanagement(ysfR3Plugin)

‣  R3‐http://developer.yahoo.com/r3/

‣  IntegratesupportforY!UserInterfacelibraries(ysfYUIPlugin)‣  Createdabuildanddeploymentsolution(ysfBuildPlugin)

Localizingtheexperiencewithdimensions‣  CascadingConfigurationbasedonYAML

‣  Framework‐>Project‐>Application‐>Module

‣  Extendingthecascadetobebasedondimensions

‣  Dimensionscanbeanything(andcanbechainedtogether)

‣  DataCenter+Environmentforcustomizingconfigurations

‣  Cultureforlocalizinguserinterface+data‣  Themeforcustomizinglookandfeel

‣  Userinfo(isuseroncorporateintranet?)‣  Caching

Extendingtheview+i18nsystemwithR3+intl‣  Translation+TemplateManagement

‣  Integratedwithsymfonyi18n+viewlayers

‣  <r3:trans>hello</r3:trans>vs__(‘hello’)‣  DictionaryManagement

‣  SQLite/XLIFFBackend‣  r3:include,r3:var,r3:cphp

‣  Addedtasks‣  Importing/ExportingXLIFFdictionary

‣  Generatingtranslationsforprojects‣  UseINTLextension+graphme_*function(replacesmbstring)

YahooUserInterfacelibraries‣  YUILogger/Debugger‣  EventSystem(unobtrusivejavascript)

‣  Helpers‣  AJAX(link_to_*,*_to_remote)

‣  Forms

‣  Widgets(RichTextEditor+Slider+Calendar)

Abuildanddeploymentsystem‣  Aggregateandminifystylesheetsandjavascripts

‣  Rewritetemplates,css,jsforCDN(Akamai,S3,…)

‣  Generatetranslationsforconfigurations+templates

‣  Generateconfigurationcache‣  Aggregatecoreclasses+removedebugstatements

‣  Runlint,unit,functionaltests‣  Packageapplications‣  ReplacewithPEARor.debor.rpm

‣  Deploymentviapackages

‣  Manageenvironment/systemdependencies

SecurityRules‐http://developer.yahoo.com/security/

‣  XSS‣  FilterInput‣  Usefilterextension‣  EscapeOutput‣  symfonyoutputescapingisslow,butsafe

‣  Forperformance,escapemanually

‣  CSRF‣  Alwaysvalidateformstousers

YSlowRules‐http://developer.yahoo.com/performance/1.MakeFewerHTTPRequests

2.UseaContentDeliveryNetwork

3.AddanExpiresoraCache‐ControlHeader

4.GzipComponents

5.PutStylesheetsattheTop

6.PutScriptsattheBottom

7.AvoidCSSExpressions

8.MakeJavaScriptandCSSExternal

9.ReduceDNSLookups

10.MinifyJavaScriptandCSS

11.AvoidRedirects

12.RemoveDuplicateScripts

13.ConfigureETags

14.MakeAjaxCacheable

15.FlushtheBufferEarly

16.UseGETforAJAXRequests

17.Post‐loadComponents

18.PreloadComponents

19.ReducetheNumberofDOMElements

20.SplitComponentsAcrossDomains

21.MinimizetheNumberofiframes

22.No404s

23.ReduceCookieSize

24.UseCookie‐freeDomainsforComponents

ProfilingandDebugging‣  Xdebug/Kcachegrind/Valgrind

zend_extension=/usr/local/.../xdebug.so

xdebug.profiler_enable=1

xdebug.profiler_aggregate=On

xdebug.profiler_output_dir=/tmp

kcachegrindcachegrind.out.aggregate.*

‣  PEARincluedextension=inclued.so

inclued.enabled=1

inclued.dumpdir=/tmp

php~/pecl/inclued/gengraph.php‐iinclude

Doityourselfforcheap‣  Opensourcesoftware=Free

‣  Apache

‣  PHP

‣  MySQL‣  Memcache/Perlbal/MogileFS/Squid

‣  symfony/Propel/Doctrine/Swift

‣  Nagios

‣  AmazonSharedInfrastructure=Cheap

‣  EC2CloudComputing

‣  S3DistributedStorage‣  SimpleDB

Booksworthreading

Questions?

Directandindirecthelpfrom...

•CalHenderson,Flickr•SaraGolemon,Yahoo!•RasmusLerdorf,Yahoo!•SteveSouders,Google

ThanksforlisteningandenjoytherestofsymfonyCamp2008!

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