WIRED is a framework, written in Java, to build High Energy Physics event displays that can be used across the network. To guarantee portability across all platforms, WIRED is implemented in the Java language and uses the Swing user interface component set. It can be used as a stand-alone application or as an applet inside a WWW browser. The graphical user interface allows for multiple views and for multiple controls acting on those views. A detector tree control is available to toggle the visibility of parts of the events and detector geometry. XML (Extensible Markup Language), RMI (Remote Method Invocation) and CORBA loaders can be used to load event data as well as geometry data, and to connect to FORTRAN, C, C++ and Java reconstruction programs. Non-linear and non-Cartesian projections (e.g. fish-eye, rho-phi, rho-Z, phi-Z) provide special views to get a better understanding of events. WIRED has grown to be a framework in use and under development in several HEP experiments (ATLAS, CHORUS, DELPHI, LHCb, BaBar, D0 and ZEUS). WIRED event displays have also proven to be useful to explain High Energy Physics to the general public. Both CERN, in its travelling exhibition and MicroCosm, and RAL, during its open days, have displays set up

Ballaminut, A

Colonello, C

Dönszelmann, M

Korhonen, J

Köper, D

Litmaath, M

Perl, J

Theodorou, A

Van Herwijnen, Eric

Whiteson, D

Wolff, E

CERN Document Server

WIRED - World Wide Web Interactive Remote Event Display1A. Ballaminut1, C. Colonello1, M. Dönszelmann2, E. van Herwijnen2, D. Köper3, J. Korhonen4, M. Litmaath5, J. Perl6, A. Theodorou2, D. Whiteson2, E. Wolff21 Dipartimento di Fisica, Università degli Studi di Udine, Via delle Scienze 208, 33100 Udine, Italy 2 CERN, CH-1211 Geneva 23, Switzerland 3 NIKHEF, P.O.Box 41882, 1009 DB Amsterdam, The Netherlands 4 University of Oulu, Linnanmaa BOX 4500, FIN-90401 Oulu, Finland 5 Fermilab, P.O.Box 500, Batavia IL 60510-0500, U.S.A. 6 SLAC, P.O.Box 4349, Stanford CA 94309, California, U.S.A.AbstractWIRED2 is a framework, written in Java, to build High Energy Physics event displays that canbe used across the network. To guarantee portability across all platforms, WIRED isimplemented in the Java language and uses the Swing user interface component set. It can beused as a stand-alone application or as an applet inside a WWW browser.The graphical user interface allows for multiple views and for multiple controls acting onthose views. A detector tree control is available to toggle the visibility of parts of the eventsand detector geometry. XML (Extensible Markup Language), RMI (Remote MethodInvocation) and CORBA loaders can be used to load event data as well as geometry data, andto connect to FORTRAN, C, C++ and Java reconstruction programs. Non-linear andnon-Cartesian projections (e.g. fish-eye, rho-phi, rho-Z, phi-Z) provide special views to get abetter understanding of events. WIRED has grown to be a framework in use and under development in several HEPexperiments (ATLAS, CHORUS, DELPHI, LHCb, BaBar, D0 and ZEUS). WIRED eventdisplays have also proven to be useful to explain High Energy Physics to the general public.Both CERN, in its travelling exhibition and MicroCosm, and RAL, during its open days, havedisplays set up.Keywords: HEP Event Displays; Java; RMI; XML; CORBA1 IntroductionThe initial version of WIRED[1] was written to study the, at that time, still immature Javatechnology on the DELPHI experiment by creating a fairly visible application, an event display.WIRED was an applet that could be downloaded in a WWW browser, and physicists all over theworld could see and study events. Over time Java matured, became quite a lot faster and moreportable. The early version of WIRED was rewritten completely to accomodate multipleexperiments and to put emphasis on the visualization of High Energy Physics events.Today WIRED[2] is a framework[3] to build High Energy Physics event displays. It can runin stand-alone mode or in a web browser and in either mode it can have remote access to data viaa CORBA or RMI server. Experiments normally extend the framework via plug-in modules to giveWIRED some experiment-specific behaviour. WIRED comes with a powerful graphics engine,which is specially made to handle the display of events in different and sometimes specialprojections. 1 A longer version of this paper is also available.2 URL: http://wired.cern.ch/CERN-IT-2000-0031 March 20002 ArchitectureThe architecture of WIRED is based around a client-server model. WIRED can be run in threedifferent basic configurations, as shown in Figure 1. In the first configuration the client is run instand-alone mode, pre-installed on a machine, with local access to geometry and event data on thatmachine in the form of files. The second configuration is different from the first in that the clientnow receives its geometry and/or event data from a remote server. Local access to data is stillpossible. In the last configuration WIRED is run as an applet inside a browser. The actual WIREDcode is downloaded from a WWW server and for geometry and event data the same server as inthe second configuration is used. Due to security restrictions no local data access is possible. Otherconfigurations, which involve gateways to stream the data via specified servers, are also possible.The authors chose to implement WIRED in the Java language[4] using the Swing user interfacekit[5], both of which allow for easy portability and running as an applet. The server may be writtenin another language, such as C or C++, to allow for easy coupling with an event reconstructionframework.The WIRED client Graphical User Interface contains a View Top and a Control Top, asshown in Figure 2. The first allows the user to create several different views on his event. Eachview can be directly manipulated with the mouse and context sensitive popup menus allow the userto do most of the interaction. The Control Top shows the different controls, which may act on oneor more selected views. These controls can show the status of different views and allow for morecomplicated interaction. An optional console will be added to allow the user to interact via aFigure 1:   WIRED running in three different configurations: a - stand-alone, with local code, geometry andevent data, b - in client-server mode, with local code, but remote geometry and event data and c - in browsermode, where code, geometry and event data are all downloaded into an applet inside a web browser.WIREDServerWIREDApplicationWIREDCodeGeometryand/or WWWBrowserWWWServerGeometryand/or EventsWIREDApplicationWIREDCodeWIREDAppletWIREDServerGeometryand/or EventsWIREDCodeabcscripting language. The client as a whole, the Menubar, Toolbar, View Top, Control Top andConsole, is an applet which can be used in browser mode.3 Data AccessEvent and geometry data is read into WIRED using a loader. This loader may load data from a localor remote file system, by using for instance XML, or it may use a communication protocol, suchas CORBA or RMI, to access a remote server and load objects directly into memory.XML is a standard to define human and machine readable formats[6]. WIRED uses XMLto define generic and specific formats for writing out geometry and event files from reconstructionor analysis programs. Though no true interaction between WIRED and the supplying program ispossible, XML provides a fairly easy mechanism to have access to data. An off-the-shelf XMLparser and other XML tools are used in WIRED.RMI (Remote Method Invocation) or CORBA[7] can be used to provide a direct connectionbetween WIRED and an event reconstruction program. RMI only allows Java to Java connections,however the JNI (Java Native Interface)[8] can be used to interface to other languages. CORBAprovides an alternative to connect to remote servers written in Fortran, C or C++. Both RMI andCORBA allow the full event object structure to be transported into WIRED.Different experiments opt for different solutions. WIRED uses a class plug-in structure, seeFigure 3, to specify the option used. Two experiment-specific loaders need to be written to loadboth geometry and event data. Both loaders, which either use XML, CORBA or RMI, will mapgeometry and event data onto so called representables. These representables are for instance piecesof the detector, tracks, tracker hits or calorimeter hits, and each contain enough information to bedisplayed. The graphics engine takes the representables, converts them, and shows them on thescreen. The integration of a generic interface for both representables and their representation isongoing[9]. .4 Graphics EngineThe WIRED graphics engine[10] uses a traditional graphics pipe[11] to convert data beforedisplaying it (see Figure 3). Representables (tracks, hits, calorimeter hits, ...) are represented byFigure 2:   The WIRED Graphical User Interface: on the left the stand-alone version of WIRED showing theATLAS detector in two views on the view top. The control top shows the component structure of the event.Toolbar and menubar allow for access to general functionality, while popup menus allow for view specificfunctionality. On the right the browser version of WIRED, showing the BaBar detector, with identicalfunctionality.Menu BarView Spe-cific Popup Tool BarView TopControl TopConsoleWIRED Applet inside the Netscape broswerprojectables (squares, lines, ...) by using representations (hit as square, track as line, ...). Theseprojectables are 2D symbols with 3D coordinates. These coordinates are then projected intodrawables by using one or more cascaded projections. Drawables are 2D symbols with2D coordinates and can therefore be drawn on the screen. The use of 2D symbols for hits becomesclear, see Figure 4, when the hits of an event should always be recognizable even if one zoomedout very far. A traditional 3D graphics engine will scale down the hits accordingly, while theWIRED graphics engine keeps its symbols - the hits - at the same size. WIRED provides a set ofstandard representables, projectables and drawables and some standard representations andprojections, to convert one into the other.Projections in WIRED are specified in terms of functions and can therefore be linear as wellas non-linear. Parallel, flat, scalable, rho-fish-eye, XYZ-fish-eye, rho-phi, rho-Z and phi-Z are afew of the many possible standard projections, and the user can easily extend this set. Projectionscan be cascaded: for instance, to obtain a scalable rho-fish eye one would apply a scalableprojection followed by an rho-fish-eye projection. Special projections can be very useful toenhance a particular aspect the user is studying[12]. The rho-fish eye projection, for instance,blows up the inner parts and compresses the outer parts of the detector, thereby not sacrificing thevisibility of the latter, as would be the case for an ordinary scalable projection.The drawables, which appear on the screen, are layered to allow the event to be drawn ontop of less important geometry information. Layering also handles the drawing of thin framesaround the drawables and this enhances the clarity of the picture substantially.5 ConclusionsWIRED provides a framework in Java to write High Energy Physics event displays. It is highlyportable, runs as a stand-alone application or as an applet inside a WWW browser. It uses aclient-server architecture to allow the user to access geometry and or event data locally orremotely. The Graphical User Interface with its View Top and Control Top allow the user to easilyFigure 3:   The plug-in architecture of WIRED. Several mandatory experiment specific plug-in classes areneeded to tell WIRED what to show on the screen. Optional plug-in classes may add extra functionality andbehaviour to WIRED.EventLoaderGeometryLoaderRepresentationsProjectablesProjectionsDrawablesRepresentablesEvent and Geometry CacheRepresent ProjectGUIGraphical User InterfaceOptional experiment specific plug-in classesMandatory experiment specific plug-in classesWIREDApplication or Appletview events in different ways and to interact with them. Three methods of accessing data, viaXML, CORBA or RMI, provide every experiment with a way to write their plug-in modules.WIRED’s powerful graphics engine is unique in the sense that it handles non-linear andnon-cartesian projections. The layering model used by the graphics engine produces nicelyenhanced pictures.References1 M.C. Coperchio, M.Dönszelmann, P. Gunnarsson, “WIRED - World-Wide Web Interactive Remote Event Display”, 1997 CERN-97-01. 2 M.C. Coperchio et al., “WIRED - World-Wide Web Interactive Remote Event Display”, Computer Physics Communications 110 (1998) 155-159. 3 Don Roberts and Ralph Johnson, “Evolving Frameworks: A Pattern-Language for Developing Object Oriented Frameworks”, Pattern Languages of Program Design 3, Addison-Wesley, 1998.4 James Gosling, Bill Joy and Guy Steele, “The JavaTM Language Specification”, Addison-Wesley, 1996.5 Robert Eckstein, Marc Loy & Dave Wood, “Java Swing”, O’Reilly, 1998.6 Tim Bray et al., “Extensible Markup Language (XML) 1.0”, W3C, 1998.7 Elliotte Rusty Harold, “Java Network Programming”, O’Reilly, 1997.8 Rob Gordon, “Essential JNI: Java Native Interface”, Prentice-Hall, 1998.9 Joseph Perl, “HepRep: a Generic Interface Definition for HEP Event Display Representables”, SLAC-PUB-8332, Stanford, California, January 2000.10 A. Ballaminut, “A Graphics Engine for High Energy Physics Event Displays”, Thesis, University of Udine, Italy, 1997/1998.11 J.D. Fowley et al., “Computer Graphics: principles and practice”, 2nd Edition, Addison-Wesley, 1996.12 H. Drevermann, D. Kuhn, B.S. Nilsson, “Event Display: Can we see what we want to see?”, 1995 CERN-ECP/95-25.Figure 4:   Conventional 3D graphics engines scale all volumes they draw (top graphs), while the WIREDgraphics engine scales the 3D coordinate, but not the symbols, such as the hits and the tracks (bottomgraphs). Frames/shadows around the symbols enhance the visibility of the picture.Scaling using theWIRED graphics engineScaling using a 3D graphics engineAll drawables are based on volumeAll drawables are based on fixed sized symbolsBetter visible picture by using frames/shadows behind tracks and hits

WIRED: World Wide Web Interactive Remote Event Display

WIRED: World Wide Web Interactive Remote Event Display

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