Rousseau, B

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INFORMATION SYSTEMS FOR PHYSICS EXPERIMENTS (Part 1)Bertrand RousseauInformation and Programming Technology GroupCERN, Geneva, SwitzerlandInformation Systems are software applications that allow their users to obtain information, and topublish information for other users. For a physics experiment the word “information” covers a largevariety of data and documents, ranging from physics events to technical reports, mechanical drawingsand electronics drawings, simulation results, source code, minutes of meetings, articles, pictures, etc.Information Systems are important for physics experiments, because they can strengthen the cohesionof a geographically sparse collaboration, they allow physicists to participate more actively and theyimprove efficiency of work. As shown in the figure below, information systems for physics experimentsmay be classified in 4 main categories (not necessarily exclusive).Groupware gathers software applications such as video-conferencing, whiteboards, email, butalso discussion lists and workflow. Product Data Management (PDM) Systems are used to manage thedata required in the design, construction and maintenance of complex products such as detectors (seethe CEDAR project below). Detectors generate on-line and off-line data that need to be made available.Finally, physics collaboration rely upon dissemination of data and documents such as internal reports,papers, user manuals, address books, general services and even source code (see the LIGHT projectbelow).1 THE STRUCTURE OF INFORMATION SYSTEMSInformation systems have 3 main components, respectively for the production, storage and delivery ofinformation. Because it is multiplatform, accessible world-wide and provides a uniform and naturalinterface, the WWW appears an excellent way of delivering information. Recent technologicalbreakthrough (JavaScript, DOM, Cascading Style Sheets, Dynamic HTML) have even reinforced theusefulness of the Web. Nevertheless, the WWW is not sufficient by itself because, in High EnergyPhysics, most information is neither produced nor maintained in HTML form. Numerous examples canbe mentioned: detectors’ real time data, word processors files, information stored in DatabaseManagement Systems, data encoded in proprietary formats of various software applications, etc. Inorder to make all this information available on the WWW, two solutions exist:On-line +Off-line DataDisseminationInformationGroupwarePDM– convert native information to HTML and/or to a WWW browsable format. This solution applies toslow changing, poorly structured information. Examples of systems using this strategy are HTMLconverters for word processors such as LaTeX, MS Word or FrameMaker [1].– store information in the most appropriate form, and convert it to WWW form “on the fly”, uponrequest. This solution is more appropriate for fast changing, structured information. The technologyinvolved covers Common Gateway Interfaces, Database interfaces, scripting languages such asJavaScript, Java, WebObjects, etc.2 THE LIGHT PROJECT - LIFE CYCLE GLOBAL HYPERTEXTThe LIGHT System, developed in the IPT Group at CERN, uses a combination of both solutions. Thegoal of LIGHT is to improve software understanding and maintenance by making available on theWWW all documents produced during the software development life-cycle: requirements, analysis anddesign diagrams, source code, user documentation, etc. To do so, all documents are converted to HTMLin such a way that hypertext links are automatically generated between the documents. For instance, afunction call may be linked to the reference manual that documents it, a class box in an OMT diagramis linked to the corresponding class definition in the C++ code, etc. This system is now in production inALEPH off-line [2], and is currently applied to other experiments such as DELPHI and ATLAS [3].3 PRODUCT DATA MANAGEMENT SYSTEMS - THE CEDAR PROJECTOther examples of information Systems are Product Data Management (PDM) systems. The goal of theCEDAR project is to implement a PDM system at CERN, for the LHC accelerator and experiments [4].A PDM system is built around of an electronic data vault. The basic idea is that data files produced byusers with various applications (e.g. Euclid, FrameMaker, MS Project) are made known and referencedby the PDM system, to become “Managed Files”. Once known by the PDM system, a file can only berequested or updated through the EDMS. The PDM system may be accessed by users providing and/orconsulting files. Users may be located at CERN, in external institutes or in companies. Users canbrowse and request the data vault with the native PDM system user interface, or through a WWWinterface that guaranties world-wide access. Access is controlled by a system of privileges specified bythe PDM system administrators.The meta-data superimposes structure and semantics to the set of controlled files. To do so, itrecords the location, nature, status, authors, versions ... of each file, but also the relationships anddependencies between data (e.g. product structure, documentation, ...). Users are notified of newreleases and changes in the data vault that may affect their work. At the occasion of releases, Managersand Coordinators are requested by the PDM system to approve, reject or comment the changes.You can find more complete information, as well as the slides of the lectures, articles and relatedWWW pointers at the following URL:http://www.cern.ch/IPT/CSC/1997/REFERENCES[1] B.Rousseau, M.Ruggier, “Writing Documents for Paper and WWW. A Strategy based onFrameMaker and WebMaker”, Presented at First International WWW Conference, Geneva,Switzerland, May 25-27, 1994.[2] A.Aimar, M.Aimar, M.Cattaneo, P.Comas Illas, A.Khodabandeh, P.Palazzi, B.Rousseau,M.Ruggier, “Using WWW to Improve Software Development and Maintenance: Application ofthe LIGHT System to ALEPH Programs”, Presented at Computing In High Energy Physics, Rio deJaneiro, Brazil, September 18-22, 1995.[3] A.Aimar, L.M.Barone, P.Krysiuk, P.Palazzi, B.Rousseau, “LIGHT/OO: an extension of LIGHT toOO development”, Presented at Computing In High Energy Physics, Berlin, April 7-11, 1997.[4] B.Rousseau, N.Hoimyr, C.Hauviller,”Implementing an Engineering Data Management System forthe LHC Accelerator and Experiments: The CEDAR Project”, Presented at Computing In HighEnergy Physics, Berlin, April 7-11, 1997.

Information systems for physics experiments, pt.1

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