The construction of the Large Hadron Collider, LHC, at CERN implies both the handling of a huge amount of information and the control of the coherence of this information. The LHC machine parameters have to be maintained coherent as the design evolves from the conceptual stage to the actual, installed, machine and have to be made available to all concerned. Design data is provided in many different formats from the machine builders, drawings, technical documents, meeting notes, lattice simulation input files, etc. The World Wide Web is being used to make the information accessible both at CERN and at the external collaborating laboratories. In this paper we describe the implementation of an Oracle database as the central common repository for machine parameters and of information for the automatic generation of CAD layout drawings and WWW pages. This system is integrated in a larger context, the EDMS system for the LHC project, which encompasses both the accelerator and the experiments

Mallon, S

Mottier, M

Pettersson, Thomas Sven

Risselada, Thys

Wildner, E

CERN Document Server

EUROPEAN ORGANIZATION FOR NUCLEAR RESEARCHEuropean Laboratory for Particle PhysicsCERN   EST/98-05 (ISS)THE INFORMATION SYSTEM FOR LHC PARAMETERS ANDLAYOUTSS. Mallon, M. Mottier, Th. Pettersson, T. Risselada, E. WildnerAbstractThe construction of the Large Hadron Collider, LHC, at CERN implies both the handling of ahuge amount of information and the control of the coherence of this information. The LHCmachine parameters have to be maintained coherent as the design evolves from the conceptualstage to the actual, installed, machine and have to be made available to all concerned.  Designdata is provided in many different formats from the machine builders, drawings, technicaldocuments, meeting notes, lattice simulation input files, etc. The World Wide Web is being usedto make the information accessible both at CERN and at the external collaborating laboratories.In this paper we describe the implementation of an Oracle database as the central commonrepository for machine parameters and of information for the automatic generation of CAD layoutdrawings and WWW pages. This system is integrated in a larger context, the EDMS system forthe LHC project, which encompasses both the accelerator and the experiments.Paper presented at the Sixth European Particle Accelerator Conference22-26 June 1998, City Conference Centre, Stockholm, SwedenGeneva, SwitzerlandDecember 1998- 2 –1. AIMThe Information system for the LHC Parameters and Layouts has been created with the aimto always have an up to date set of the LHC baseline information accessible to the community ofpeople working with the LHC project. The baseline information is the set of approved and releaseddocuments that represent the definition of a product at a specific point in time. Configuration baselinesare established whenever it is necessary to define a reference configuration during the product's lifecycle. This baseline is then used as a starting point for further activities. To keep the baselineinformation up to date implies considerations about the coherence of the parameter set, the uniquenessof the source of the information, updates and the necessity of keeping track of updates, informationretrieval, the way of presenting the information and access rights. Important are also the integrationinto the general Engineering Data Management System for the LHC Project ([1]) and the links to otherparts in the EDMS system.2. SCOPEAll elements and concepts for the LHC should be stored in the system. Automatic generationof beam optics input files and layouts of the machine from the machine description, also stored in thesystem, can be done by using the entities in the database describing the different magnets and otheraccelerator systems. CERN Drawing directory can also be visualised.The system should also guarantee the correctness and coherence of data that might be ofinterest for several groups of people. Links are made available to more detailed information thatinterests only a limited number of people. A history of modifications with date and references are kept.A simple search mechanism permits to find pages containing a specified string. Statistics of the accessto the pages is accessible.3. STRUCTURE FOR STORING THE PARAMETERSMagnets and cavities are examples of physical objects, they have parts and they have aphysical structure. They also have properties (i.e. field) related to parameter settings (i.e. current). Onecan also say that the accelerator is a physical object, with a structure, with parameter settings, andproperties, however, a strict view of the objects is really beneficial only when we have many objects ofthe same kind. Then we can reuse the same templates for several objects. We confound "parameters"and "properties" in what follows; for example field and current for a magnet are both parameters.Above a certain level of detail an object may have a parameter that influences the beam. Atthe highest level, the accelerator, the beam parameters (the specification of the performance of themachine) are defined. Each beam parameter has associated to it a definition. It is possible to definerelations to other beam parameters and to calculate automatically derived parameters.The data has been structured to correspond to the product breakdown structure defined formanaging the project data (drawings, specifications etc.), the PBS. In this way parameter tables can beeasily accessed, not only from the special interface for parameters and layouts, but also from thecorresponding nodes in the PBS.The parameter pages have links to reference papers, minutes of meetings, layouts and to theCERN drawing directory.4. IMPLEMENTATION4.1 The implementation of the parameter databaseThe entity-relationship model is used to implement the idea of objects and parameters relatedthrough a set of parameter values. The "is_a / can_be" rules implements the inheritance. There are- 3 –objects of type "model" from which other object may inherit its set of parameters, with or without itsset of values. The "pbs_child / pbs_parent" is a reflexive relationship that indicates the fact that anobject may be made up of other objects. With this relationship the parts breakdown structure can bemodelled. The "has / for" relationship describes the fact that an object may have one or moreparameters; a parameter may be applied to one or more objects. Each pair object-parameter has a singlevalue. In this way we try to have unique definitions of parameters that can be reused for severalobjects.The choice of ORACLE tools for the implementation was based on the fact that this is theonly system that is maintained at CERN. Prototyping in other systems (object oriented) was carriedout, but these systems did not have enough maturity for our needs. During the design phase the OracleCASE tool Designer/2000 was used to help in the modelling and to generate the code.4.2 Layouts and drawingsDifferent types of layout drawings are required throughout the project's life cycle. In thedevelopment phase conceptual layouts are used to allocate space to the machine components along thebeam line. This process does not lend itself to easy automation, as proposed solutions have to benegotiated between groups and individuals responsible for the design of the components. Once asuitable conceptual layout is achieved, its data, essentially the location and size of each machinecomponent, can be entered into the database. After verification of the coherence of the layout with theMethodological Accelerator Design (MAD) program, the data can be used to automatically produceschematic and installation layout drawings which are essential for a successful and timely installationof the machine. Schematic linear layouts, in which components are represented by simple boxes, areproduced with AutoCAD whereas more detailed representations are produced with the 3D CADsystem Euclid, using a library of 3D models of the machine components.Approved changes (following an Engineering Change Request, ECR) are implemented bymodifying the locations of components in the database and by modifying the 3D models in the library.This is followed by the production of a new set of layouts with the CAD application.4.3 The implementation of the optics file generationA complete description of the future "LHC installed in its tunnel" is stored in the machinedatabase tables (presently about twelve thousand elements). For the moment local tables are used butin the future the information will be obtained through links to the LHC machine database, so as tohave a unique source for all parameters.The LEP Database ([2]), used for current machine operation, was taken as a starting point. Asthe LHC has two rings the tables had to be extended to handle the ring information. The toolsgenerating data to be used in beam optics calculations and to produce layout drawings were equallymodified to handle the two rings, and were shown to work well.Complete MAD input data files are created for both rings, using unique names.Unfortunately each modification of the machine layout still requires a large amount ofmanual intervention to the database tables. New methods are presently explored to accelerate thisprocess in such a way that after layout changes new drawings and beam optics input data can berapidly made available.The input file for optics calculations with MAD is generated entirely from the database by aprogram written in Pro*C- 4 –5. THE PRESENTATION OF THE BASELINE PARAMETERSThe presentation of the parameters is also automated to ease the maintenance of theinformation and the creation of new pages. All the World Wide Web pages are created automaticallyand have the same layout, see figure 1. This means that all pages benefit from updates and newutilities, and that the general layout of the pages can be easily modified. The pages are kept simple andwith limited possibilities to escape the page structure via hyperlinks. They are kept in a tree structure,with chapters and subchapters.The database is keeping the contents of the pages and also information about the title of thepage, its set of navigation buttons and the type of contents. The type of contents can be for example astatic text or a list of parameters for a table. General procedures are written to build the tables.This WWW Interface is programmed in PL/SQL, using the Oracle Web Server.The layout drawings are managed with the CERN Drawing Directory (CDD) application [3]like all other LHC project drawings. Associated to the CERN developed HPGL viewer this givesaccess to the drawings via the WWW for display on computer screens, for reviewing and for printing.Another presentation on the WWW uses the Computer Graphics Metafile (CGM) format.This offers interesting possibilities to link the graphic elements of a drawing to other drawings,documents or database records. This approach makes it possible to navigate graphically through thewhole set of layout drawings and associated parametersFigure 1: Example of automatically generated page.- 5 –6. OUTLOOKThe system is dynamic; extensions and refinements are continuously put into the system andmore complete reference lists set up.For the parameters describing the beam, definitions and relations will be put into the system.The information stored in the system is the basis for the LHC Design Report and it will bepossible to generate tables and other data directly from the database.More work on the database is needed to ensure the maintenance over the project lifetime.7. REFERENCES[1] C.Delamare, F.Dittus, R.Evensen, M.Ferran, C.Hauviller, B.Faugeras N.Hoimyr, M. Mottier,J.Nikkola , T.Pettersson , B.Rousseau, H.van der Welde, G.Faber, "The CEDAR Project", thisconference.[2] A. Albrecht et al., "CERN's Accelerator Description Using Databases", Proceedings of the 1992European Oracle Users Group Meeting, March 1992.[3] C.Delamare, I.Fernandez, F.Jeannin, S.Petit, "CDD CERN Drawings Directory User's manual:Version 1.1", CERN-EST-96-004.

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