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1、24-Mar-2003,K. Wrona, A ROOT-based Client Server Event Display for ZEUS,1,A ROOT-Based Client-Server Event Display for ZEUS,Krzysztof Wrona, Oliver Gutsche and Rainer Mankel (DESY Hamburg) Computing in High Energy Physics 2003 24-Mar-2003,24-Mar-2003,K. Wrona, A ROOT-based Client Server Event Displa
2、y for ZEUS,2,Outline,24-Mar-2003,K. Wrona, A ROOT-based Client Server Event Display for ZEUS,3,Motivation for New ZEUS Event Display,During the HERA luminosity upgrade, new detector components have been installed which require extended 3D capabilities Example: Micro-vertex detector (MVD), straw tube
3、 tracker (STT) Needed a non-monolithic solution, which includes analysis software as a modular component Client/server approach allows clear separation lightweight client (purely C+, no experiment libraries) server application (encapsulates legacy code),ZeVis,= Zeus Visualization,24-Mar-2003,K. Wron
4、a, A ROOT-based Client Server Event Display for ZEUS,4,Architecture,ZClient Main client application & GUI,ZEvtBuild ZEUS event to ROOT conversion,ZGeomBuild ZEUS geom to ROOT conversion,ZevLib Detector objects,ZevLibX ZEUS DDL interfaces,other ZEUS software,ZesAgent Event agent for server,ZClient is
5、 a lightweight client application which only depends on ZevLib and ROOT,24-Mar-2003,K. Wrona, A ROOT-based Client Server Event Display for ZEUS,5,Data Model,Clear separation of geometry and event information to minimize amount of data transfer,Geometry: only needs to be loaded once (or few times at
6、most) optimize for fast drawing. All ZEUS geometry classes derive from corresponding shapes in ROOT. Geometry can draw itself independently present size 450 kB,Event: many ROOT-files to be transferred & stored (cached) file contains tree of event-objects objects contain drawable event information (e
7、.g. track objects), refer to geometry information during drawing, cannot be drawn independently optimize for size. Data structure similar to ZEUS miniDST about 30 kB/evt,24-Mar-2003,K. Wrona, A ROOT-based Client Server Event Display for ZEUS,6,Implementation With ROOT,Parallel implementation of 3D d
8、isplay and layered 2D projections is achieved by overloading “Paint()” member function in 3D mode, use Paint() function of basic ROOT class in 2D mode: 3D-object contains list of 2D-representation-objects Paint() function draws list of objects according to the desired projected shape Fish-eye view i
9、n XY and ZR projection to allow simultaneous inspection of inner (MVD) and outer detector (muon system) achieved by overloading TView:WCtoNDC function Extensive use of picking functionality and “describe object below mouse pointer” Extension of TWebfile class to integrate feedback from server For co
10、ntrol room, special mode which periodically loads the next online event,24-Mar-2003,K. Wrona, A ROOT-based Client Server Event Display for ZEUS,7,Integration of 2D/3D views,Perspective views with hidden surface removal are useful for understanding geometry, but do not show the event well,24-Mar-2003
11、,K. Wrona, A ROOT-based Client Server Event Display for ZEUS,8,Client-Server Motivation,Event display needs access to experiments event store and online system Idea: separation of portable lightweight client, which can run wherever ROOT can run central geometry & event server on DESY site and connec
12、t via HTTP protocol (ROOTs TWebFile) to pass firewall,control room,office on-site,off-site, home,Central ZeVis Server (1 Dual-Xeon 2GHz),LAN,LAN,WAN,HTTP,Mass storage,User work station,DESY Computer Center,24-Mar-2003,K. Wrona, A ROOT-based Client Server Event Display for ZEUS,9,Internal Structure o
13、f The ZeVis Server,Geometry request,Single event request,File request,Geometry Builder,Event Store,Tag DB,Online Reconstruction,Online event request,EOTW request,Constants DB,24-Mar-2003,K. Wrona, A ROOT-based Client Server Event Display for ZEUS,10,Components of The ZeVis Server,Single event server
14、 random access to event from ZEUS Event Store and conversion to ROOT format on-the-fly normally based on run/event number, optionally with query on about 300 tag variables per event (both modes involve tag database, Objectivity/DB 7.0) staging handled by dCache system if necessary for low latency, t
15、he “event agents” are pre-initialized and wait for a request passed to them (daemon-fashion) 10 event agent processes per software release (pro + dev), 20 in total Online event server online system splits RAW events off the event stream at about 0.1 Hz on-the-fly reconstruction and ROOT conversion o
16、n dedicated server Geometry and propaganda events static ROOT files on the server, which are produced offline download of geometry file takes 1s,24-Mar-2003,K. Wrona, A ROOT-based Client Server Event Display for ZEUS,11,(no server cache),Server Performance,Stress test,Less than 2 s average response
17、time even faster on cached events this includes event analysis and conversion to ROOT format,In reality, simultaneous requests will hardly occur at all Server can stand up at least 4 requests in parallel without noticeable performance loss,24-Mar-2003,K. Wrona, A ROOT-based Client Server Event Displ
18、ay for ZEUS,12,Graphical User Interface,24-Mar-2003,K. Wrona, A ROOT-based Client Server Event Display for ZEUS,13,GUI: Single Event Server,24-Mar-2003,K. Wrona, A ROOT-based Client Server Event Display for ZEUS,14,GUI: Download file mode,24-Mar-2003,K. Wrona, A ROOT-based Client Server Event Displa
19、y for ZEUS,15,GUI: Online Mode,24-Mar-2003,K. Wrona, A ROOT-based Client Server Event Display for ZEUS,16,Projections XY and RZ,These are the main views for event analysis Projections complement the geometry of the detector,24-Mar-2003,K. Wrona, A ROOT-based Client Server Event Display for ZEUS,17,F
20、ish-eye View,Allows to see details in the vertex detector simultaneously with the outer detectors Also available in ZR view,24-Mar-2003,K. Wrona, A ROOT-based Client Server Event Display for ZEUS,18,MVD Display,ROOT allows 3D view within a pad (wire frame only),24-Mar-2003,K. Wrona, A ROOT-based Cli
21、ent Server Event Display for ZEUS,19,Drift Chamber Raw Hits,Normally, CTD display shows assigned hits, taking drift distance into account,Special mode shows cell structure and raw hits,24-Mar-2003,K. Wrona, A ROOT-based Client Server Event Display for ZEUS,20,Muon Chambers and Hits,Muon Hits,Not yet
22、 final,24-Mar-2003,K. Wrona, A ROOT-based Client Server Event Display for ZEUS,21,Summary,Client-Server event display successfully developed with ROOT as basis highly portable, light-weight client fast geometry & event access via HTTP. Mature server design. Full integration of 2D/3D views. Online display Ergonomic GUI Excellent experience with ROOT functionality,Contributions by: U. Fricke, C. Genta, O. Gutsche, S. Hanlon, E. Heaphy, R. Kaczorowski, O. Kind, R. Mankel, J. Rautenberg, V. Sipica,Thanks to the ROOT team for help & advice (and for providing ROOT!),