A ROOT-Based Client-Server Event Display for ZEUS一根基于客户机服务器的事件显示为宙斯

AROOT-BasedClient-ServerEventDisplayforZEUSKrzysztofWrona,OliverGutscheandRainerMankel(DESYHamburg)ComputinginHighEnergyPhysics200324-Mar-200324-Mar-20031OutlineMotivationArchitecture,DataModel&ImplementationServerDesign&PerformanceGraphicalUserInterfaceDisplayexamples24-Mar-20032MotivationforNewZEUSEventDisplayDuringtheHERAluminosityupgrade,newdetectorcomponentshavebeeninstalledwhichrequireextended3DcapabilitiesExample:Micro-vertexdetector(MVD),strawtubetracker(STT)Neededanon-monolithicsolution,whichincludesanalysissoftwareasamodularcomponentClient/serverapproachallowsclearseparationlightweightclient(purelyC++,noexperimentlibraries)serverapplication(encapsulateslegacycode)ZeVis=ZeusVisualization24-Mar-20033ArchitectureZClientMainclientapplication&GUIZEvtBuildZEUSeventtoROOTconversionZGeomBuildZEUSgeomtoROOTconversionZevLibDetectorobjectsZevLibXZEUSDDLinterfacesotherZEUSsoftwareZesAgentEventagentforserverZClientisalightweightclientapplicationwhichonlydependsonZevLibandROOT24-Mar-20034DataModelClearseparationofgeometryandeventinformationtominimizeamountofdatatransferGeometry:onlyneedstobeloadedonce(orfewtimesatmost)optimizeforfastdrawing.AllZEUSgeometryclassesderivefromcorrespondingshapesinROOT.Geometrycandrawitselfindependentlypresentsize450kBEvent:manyROOT-filestobetransferred&stored(cached)filecontainstreeofevent-objectsobjectscontaindrawableeventinformation(e.g.trackobjects),refertogeometryinformationduringdrawing,cannotbedrawnindependentlyoptimizeforsize.DatastructuresimilartoZEUSminiDSTabout30kB/evt24-Mar-20035ImplementationWithROOTParallelimplementationof3Ddisplayandlayered2Dprojectionsisachievedbyoverloading“Paint()〞memberfunctionin3Dmode,usePaint()functionofbasicROOTclassin2Dmode:3D-objectcontainslistof2D-representation-objectsPaint()functiondrawslistofobjectsaccordingtothedesiredprojectedshapeFish-eyeviewinXYandZRprojectiontoallowsimultaneousinspectionofinner(MVD)andouterdetector(muonsystem)achievedbyoverloadingTView::WCtoNDCfunctionExtensiveuseofpickingfunctionalityand“describeobjectbelowmousepointer〞ExtensionofTWebfileclasstointegratefeedbackfromserverForcontrolroom,specialmodewhichperiodicallyloadsthenextonlineevent24-Mar-20036Integration

of2D/3DviewsPerspectiveviewswithhiddensurfaceremovalareusefulforunderstandinggeometry,butdonotshowtheeventwellStraight-forward“projections”of3Drepresentationcanbecomplex&confusingLayeredprojectionswithproperorderingallowtoreallyanalyzetheevent24-Mar-20037Client-ServerMotivationEventdisplayneedsaccesstoexperiment’seventstoreandonlinesystemIdea:separationofportablelightweightclient,whichcanrunwhereverROOTcanruncentralgeometry&eventserveronDESYsiteandconnectviaHTTPprotocol(ROOT’sTWebFile)topassfirewallcontrolroomofficeon-siteoff-site,homeTagDBEventStoredCacheCentralZeVisServer(1Dual-Xeon2GHz)LANLANWANHTTPMassstorageUserworkstationDESYComputerCenter24-Mar-20038Apache+ROOTmodule+PHP4GeometryfileGeometryfileGeometryfileDispatcher(PHP4)EventagentEventagentEventagentEventagentEventagentOnlineEventsROOTConversionEventsoftheWeek(PR)InternalStructureofTheZeVisServerGeometryrequestSingleeventrequestFilerequestGeometryBuilderEventStoreTagDBOnlineReconstructionOnlineeventrequestEOTWrequestConstantsDB24-Mar-20039ComponentsofTheZeVisServerSingleeventserverrandomaccesstoeventfromZEUSEventStoreandconversiontoROOTformaton-the-flynormallybasedonrun/eventnumber,optionallywithqueryonabout300tagvariablesperevent(bothmodesinvolvetagdatabase,Objectivity/DB7.0)staginghandledbydCachesystemifnecessaryforlowlatency,the“eventagents〞arepre-initializedandwaitforarequestpassedtothem(daemon-fashion)10eventagentprocessespersoftwarerelease(pro+dev),20intotalOnlineeventserveronlinesystemsplitsRAWeventsofftheeventstreamatabout0.1Hzon-the-flyreconstructionandROOTconversionondedicatedserverGeometryandpropagandaeventsstaticROOTfilesontheserver,whichareproducedofflinedownloadofgeometryfiletakes<<1s24-Mar-200310(noservercache)ServerPerformanceStresstestLessthan2saverageresponsetime

evenfasteroncachedeventsthisincludeseventanalysisandconversiontoROOTformatInreality,simultaneousrequestswillhardlyoccuratallServercanstandupatleast4requestsinparallelwithoutnoticeableperformanceloss24-Mar-200311GraphicalUserInterfaceOptiontabsStatusinformationCanvasPadsObjectinformationInputmodesZoomcontrols24-Mar-200312GUI:SingleEventServer24-Mar-200313GUI:Downloadfilemode24-Mar-200314GUI:OnlineMode24-Mar-200315ProjectionsXYandRZThesearethemainviewsforeventanalysisProjectionscomplementthegeometryofthedetector24-Mar-200316Fish-eyeViewAllowstoseedetailsinthevertexdetectorsimultaneouslywiththeouterdetectorsAlsoavailableinZRview24-Mar-200317MVDDisplayMVDClustersOccasional(well-known)fillareaclippingartifactsfromROOTROOTallows3Dviewwithinapad(wireframeonly)24-Mar-200318DriftChamberRawHitsNormally,CTDdisplayshowsassignedhits,takingdriftdistancein