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junit

LoadTestingWebApplicationsusing

Microsoft’sWebApplicationStressTool

ByRickStrahlhttp:

//www.west-

 LastUpdated:

10/17/2018

Microsoft'sWebApplicationStressToolprovidesaneasywaytosimulatelargenumbersofusersagainstyourWebapplication.Thistoolmakesitpossibletomakeintelligentdecisionsabouthardwareandsoftwareloadincurredbyyourapplicationandhowmuchtrafficagivenmachineorgroupofmachinescanhandle.InthisarticleRickshowshowthetoolworksandhowtoproperlyinterprettheperformancedataitgenerates.

FreeDownloadfrom:

Requires:

WindowsNT4.0SP4orWindows2000

BuildingWebapplicationshasnowbecomeafairlycommonscenariofordevelopersbuildingnewapplicationsorupdatingandWebenablingexistingapplications.AsapplicationsmovetotheWebintoaserverbasedenvironmentitbecomesincreasinglyimportanttobeabletogaugetheperformanceandloadcapabilityofanapplication.Developersmustbeabletoanswerhardquestionsabouthowmuchtrafficagivensitewillbeabletohandleandmakeintelligentchoicesofhardware,softwareandoftentimesevendesignapproachoftheapplicationtomakesuretheapplicationwillbeabletohandleanonslaughtofcustomersontheWebsite.Weshouldallbesoluckytohavetoworryabouttheproblemofbeingtoosuccessful!

Butit'softensurprisingtofindhowmanyWebsiteshittheirlimitsandcatchtheoperatorsoffguard.AnoverloadedWebsiteisamajorproblemandoncehappeningtheproblemoftencan'tbeaddressedrapidly.Aquickfixtypicallyinvolvesaddingadditionalhardwarethatmustbepurchased,installedandconfigured–aprocessthatmaytakedaysorevenweeks.Beingpreparedandunderstandingthelimitsofanapplicationandmanagingadvertisingtobringtraffictoasiteinmeasuredspurtsiscrucialtothesuccessoflargeandevennotsolargecommercialsites.

Additionally,it'simportanttounderstandthattoday'stoolsoftenmakeitmucheasiertobuildWebapplicationsthanthetoolsfromevenayearago.Todaywehavepowerfulscriptingengines,easyaccesstoCOMcomponentswecanwriteinhighlevellanguagesandWebserversthatself-configureforthemostpart.Butalongwiththeeaseofusealsocomesmoreoverheadandresourceloadontheserveranditbecomesevenmoreimportanttolookatloadissuesrightfromthestartofapplicationdevelopment.Loadtestingshouldbeperformedintheinitialdesignphasestogetagoodideawhatoverheadtheapplicationcomponentsincurontheserver.Constantmonitoringshouldbeperformedasdevelopmentcontinuesonalwayskeepingacloseeyeonhowwellthesoftwareplatforminrelationtothehardwareitwillberunningon.

Theproblemisthatoftentimesthesescalabilityquestionssuchas'Howmuchtrafficcanwehandleonourparticularhardware?

'arenoteasilyansweredbecauseit’shardtomeasureperformanceofWebapplicationsoutsidetheactualenvironmentthattheywillberunningin.EventheprocessoftestingWebapplicationsseemsdaunting:

TherearesomanypiecesinvolvedfromaWebbrowserclient,theWebserver,thebackendapplicationandthebackenddatabaseserver.ThebottomlineisthattheonlywaytorealisticallytesttheloadcapabilitiesofaWebapplicationisinacloseapproximationofaliveenvironment,whichmeansactually'running'theWebapplication.

IntroducingtheWebApplicationStressTool

So,howdowe'run'aWebapplicationrealistically?

Theansweristhatyouhavetosimulatemanyclientssimultaneouslyhittingyoursite.Tothisend,Microsofthasreleasedaneasytouse,yetverypowerfulandflexibletoolcalledtheWebApplicationStresstool（WAS）,whichprovidesthisfunctionalityinafreelydownloadableapplicationservice.

Figure1–TheWebApplicationStresstoolprovidesasimpleinterfacetocapture,configure,runanddisplaytheresultfromrunningastresstest.InthisviewthecapturedWeblinksthatwillbeaccessedbytheWebclientwhenrunningthetestarelisted.

WASrequiresWindowsNTorWindows2000asthetoolrunsasanNTService.Forrealisticperformancetesting,it'salsorecommendedthatyourunthestresstestingtoolfromaseparatemachineotherthantheWebserver.TheactualrequestgeneratorcanbefairlyresourceintensivewhilegeneratingtheWebrequestsandthisoverheadcanaffectperformanceoftheWebsiteundermaxloads.However,eventhoughthedocumentationstatestwomachinesarearequirementyoucancertainlyrunWASonthesamemachineastheWebserver,butdon'texpect100%accurateresultsespeciallywhenyou'retestingatthetopendloadforthehardwareyou'rerunningon.

TheuserinterfaceofWASisstraightforwardwithalistofscriptsandsublistsofthepropertiesfortheparticularscriptontheleftandadataviewontheright.Thedataviewdependsontheselectedscriptoption.Themostimportantviewsarethedefaultview（seeFigure1）thatshowsyouallselectedlinksandtheserveryou'retestingandtheSettingsview,whichconfigureshowthelinksareexecutedagainsttheserverandatwhatloadlevel.Otheroptionsallowyoutoconfigureuserswithusernamesandpasswords（optional）sinceyoucansimulatelargenumbersofclientsthismaybenecessaryforsitessecuredwithsomelevelofauthentication.Youcanevenconfigurespecificpre-existingCookievaluesforeachuserifyouhaveto.Inshort,therearealotofoptionsformostHTTPscenariosavailable,eventhoughmostoftheseareunlikelytobeutilizedintypicaltests.It'sthereforyouifyouneedthecontroltocustomizeyourtests.

Onceatesthasbeencompletedthere'sareportviewwhereyoucanviewtheresultsofthetest,whichprovidesathoroughsummaryofthetestjustperformedincludinginformationabouttotalhitsandhitspersecondasawhole,hitsforindividualpages,failuresandresponsecodesaswellasbandwidthbreakouts.

Figure2–Thereportpageprovidesasummaryofthetestrunincludingtotalnumberofrequests,requestspersecondandfailures.There'salsoadditionaldetailabouteachlinkandaveragerequesttimesofeachlink.

GettingstartedwithWAS

TheconceptbehindWASissimple:

YoucreateatestscriptbycapturingabrowsersessionusingInternetExplorerbasicallywalkingthroughyourapplication,asatypicaluserwoulddo.AsyoudothisWAScapturesthecontentofalltheseWebrequests.WAScaptureseverything:

Hyperlinkclicks,Formsubmissions,RedirectlinksandAuthenticationinfo–everythingneededtocapturetheuser'ssessionthroughyoursite.

Figure3–TheBrowserRecorderletsyouuseyourbrowsertocreatescripts.Therecordercapturesalllinks,HTMLformsubmissionsandevenCookies,RedirectsandAuthenticationinformation.

Creatingascriptisveryeasy:

YoucanusetheBrowserRecordertocaptureabrowsersessionandhaveWASgenerateatestscriptfromcapturedlinks.Amanualmodeisalsoavailabletoallowyoutomanuallyaddlinksandinformationabouteachlink.

AsyoucanseeinFigure3thereareafewoptionsyoucanchoosefortheBrowserRecorder:

Capturedelay,andrecordcookiesandhostheaders.Thedelaybetweenrequestswillresultamorerealistictestintermsofhowpeopleareactuallynavigatingasite,givingyouamoreaccuratepictureofhowusersonasitemaptoconnectionsontheWebserver.Ifyourgoalistofindthelimitsofyoursiteleavethisoptionunchecked.Ifyouwanttosimulateaspecificusernumberscenariogoaheadandcapturethedelayasitprovidesamorerealisticviewofthebrowsingscenario.I'lltalkmoreaboutthisdelaywhenwelookattheloadoptionsforthetest.

TheRecordbrowsercookiesandRecordhostheaderoptionsallowyoutocaptureaspecificusersession,ratherthandynamicallytrackingthisinformationatthetimeoftherequest,thelatterofwhichishowatypicalbrowserwouldbehave.Typicallyyou'llwanttoleavethoseoptionsuncheckedtolettheWASclientcreatecookiesandhostheadersjustlikeauseronyoursitewould.However,ifyouhavepersistentstateinformationforyoursite（suchasauserprofileorotherinfothatisconnectedtoapermanentcookie）makesurethatyouclearthecookiebeforeyourunyourteststosimulateanewusercomingtothesiteandgoingthroughthestepsofconfiguringtherequireduserstate.Forexample,onmyWebStoresiteuserssetupauserprofilewhentheyplaceanorder.TheprofileisrecoveredwhentheyreturntothesiteandtrackedwithaCookie.IfIneverwentthroughandsetupmyprofileinformationWASwouldnotbeabletoactuallyprocessanorderbecausetheprofileinformationwouldbemissingandnotgetfilledout.

IfyoutypicallyrequireuserswithanestablishedcookieandprofilethenmakesurethatyoudochecktheCapturebrowsercookieoption.

Note:

ThecurrentversionoftheWASBrowserRecorderdoesnotsupportHTTPS/SSLrequestsatthistime.TocapturerequestssecurerequestsyouhavetotemporarydisableSSL（临时禁用SSL）.IfyouhavetohaveSSLforaccuratetesting,youcanthenmanuallychangetheindividualrequestsinthelinklistandenableSSLoperationonthem.

WhenyouclickNext|Finishonthebrowserrecorderyou'llbewhiskedintoIEandyou'rereadytocapturerequestsinyourbrowser.InmycaseIranatestagainstmyWestWindWebStoreonmydevelopmentmachinestartingwiththehomepageandtypingthatlinkintothebrowser'saddressline.AfterthatI'moffonmydevsiteandwithWAScapturinglinks.ThissitehappenstobeWebstoreapplicationthatreliesonCookiestotrackusers,handlesprofileinformationforcustomersandsecureorderprocessingviaHTT