Durán, M A

García, E

Rejas, J

Rodríguez, José Alberto

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WEB-BASED DISTRIBUTED SYSTEMS FOR COLLABORATIVE REMOTEEXPERIMENTSJ.A. Rodríguez, E. García, J. Rejas, M.A. Durán, TCP Sistemas e Ingeniería, Madrid, SpainAbstractDYNACORE, an EU funded project, will providescientists and astronomers with a powerful tool forremote collaboration in experiments or observationsrequiring one or more remote facilities. One of the mainobjectives of DYNACORE is to develop  a Tele-operationsystem which can be easily adapted and optimised for aparticular instrument. To achieve these objectives, weare using an object-oriented, component-basedapproach. The user accesses DYNACORE servicesthrough a standar d, web-based man machine interface.The client software is based on Java applets, whichdirectly interact with DYNACORE servers using IIOPprotocol. OMG-CORBA is used as a high-levelinfrastructure for component interaction, includingremote Java applets. The benefits of CORBA   areextended to system design: object oriented paradigmsare used in the definition of a distributed environment,which allows to hide details about process location,operating systems and programming languages. Thesystem is used for remote opera tion of large-physicsexperiments and telescopes1  INTRODUCTIONSome scientific environments, such as Astronomy andPlasma Physics, are using increasingly sophisticated andexpensive instruments, concentrated in a few selectedplaces, sometimes driven by environmental conditions.The cost of such facilities can only be afforded by theagreement between universities, laboratories,governments and industry. In this context, experiments,observations and problem solving must be pulledtogether by scientists and engineers from differentlocations. Geographic separation becomes an essentialfactor for accomplishing cooperative research. Theworking routine and contacts are limited by the scheduleconstraints and cost imposed by travels. Thecombination of new Information and CommunicationsTechnologies can compensate the drawbacks.Collaboratory systems provide a distributed environmentfor people and instrument cooperation. Information ofdifferent kinds (not just data) can flow, and users caninteract with instruments as easily as they do when theresources are local.The goal of DYNAmically COnfigurable RemoteExperiment monitoring & control (DYNACORE), an EUfunded project, is to provide two scientific communities,Astronomy and Plasma Physics,  with such anenvironment for the collaboration on observation andexperimentation using telescopes (TNG and NOT atRoque de los Muchachos Observatory) and fusionlaboratories (TEXTOR 94 at Forschungszentrum,Jülich).A first Astro prototype has already been used by arepresentative and qualified group of validators(Astronomers) in realistic conditions (real NOTtelescope instruments in both day and night time, TNGsimulated instruments, through TNG real controlsystem). The conclusions about the satisfaction andacceptability to the users of this new way of working areencouraging. User comments and suggestions will betaken into account  in the development of a newprototype version, in order to improve the usabilityconditions of the system.2          REMOTE CO-OPERATION IN MULTI-INSTRUMENT EXPERIMENTSA collaborative system such as DYNACORE allowsgeographically distributed users and instruments tocooperate in an experiment, by providing a set ofservices for three different interaction levels (see fig. 1):• Human / Human Interaction:- A permanent information flow allowseach user to know the actions executed byother colleagues and the effects on theinstruments,- An integrated chat server allows livediscussions. Advanced tools such as video-conference can be included if supportedby the communications infra-structure.• Instruments Interaction:- Schedule co-ordination,- Data sharing,- Remote services.International Conference on Accelerator and Large Experimental Physics Control Systems483International Conference  Accel rator and L rge Experim ntal Physics Control Systems, 1999, Trieste, ItalyFigure 1: Instruments and experts cooperation.DYNACORE also provides systemadministration services for:- Users management: different roles can bedefined for different users, avoidingunauthorised use of an instrument.- System configuration,- System Under Operation (instrument)specification: commands, events andoperational rules definition,- Schedule management, Log-bookUserCategoryDescription Type of InteractionEnd-User Scientific,AstronomerExperimentation,ObservationSystemEngineerEquipmentspecialistTesting,Maintenance,Probleminvestigation,IntegrationSystemOperatorSuO specialist Local supervision,Operation servicing,Maintenance.SystemAdmin.DYNACOREspecialistUsers mngmt.,System mngmt.Table 1: User types and rolesThe web-based interface, together with thedefinition of a ‘generic’ interface model for theoperation of  a particular instrument, makespossible the access to the system from anycomputer and  with no user training.DYNACORE will mainly be used by Scientificsand Astronmers for collaborative experimentationand observation, but different users can havedifferent purposes, as shown in table1:3  DYNACORE ARCHITECTUREDYNACORE is an object-oriented, distributedsystem. OMG  CORBA (Common Object RequestBroker Architecture) is used as a  high-levelinfrastructure for distributed computing. This allows touse object oriented paradigms in the definition of adistributed environment, hiding details about processlocation, operating systems and programming languages.DYNACORE objects are distributed on client (Javaapplets on browser environment), Web server (C++agents) and DYNA server (C++ modules implementingapplication logic and basic services). Both the webserver and DYNA server can be deployed in one orseveral computers on the same LAN.Th system provides a web-based man machineinterface. The user access DYNACORE services througha standard Internet browser, including a Java VirtualMachine. The client software is based on Java appletswhich directly interact with DYNACORE servers usingIIOP (Internet Inter-ORB Protocol).The following figure describes the main logicalcomponents of DYNACORE system, and itsinteractions:HTTPEngineDYNAAgents:HE6HUYHU'<1$&25(6HUYHU6X26HUYHU'<1$VLWH5HIHUHQFH$UFKLYH,,23,,237&3,3HTTPEngineDYNAAgents:HE6HUYHU'<1$&25(6HUYHU6X26HUYHU'<1$VLWH,,23,,23,,23 ,,23+773 +773+773'<1$&25(8VHUV*HQHULF8VHUV6SHFLDOL]HG8VHUV,,23Figure 2: DYNACORE ArchitectureThe user connects the web server of a DYNACOREsystem using HTTP protocol. The required Javacode is downloaded before starting operation.Systems with real time constraints require a8VHU8VHU,QWHUDFWLRQ8VHUV9LUWXDO2SHUDWLRQV5RRP8VHU,QVWUXPHQW,QWHUDFWLRQ'<1$&25(6HUYHU'<1$&25(6HUYHU,QVWUXPHQWV,QWHUDFWLRQ9LUWXDO/DERUDWRU\484specialised interface, in order to improveperformance.- The web server hosts the HTTP engine andDYNACORE agents.- DYNACORE server is a set of CORBAcomponents, implementing the services provided bythe system.- SuO Server is a CORBA front-end to the Systemunder Operation local control system. It allowsDYNACORE to interact with the instrument.4  DYNAMICAL CONFIGURATIONVery similar instruments, from a functional point ofview, can have completely different control systems.One of the main objectives of DYNACORE project is todevelop a tele-operation system which can be easilyadapted and optimised for a particular instrument.To achieve this objective, an instrument model isstored in a DYNACORE repository. An instrument isdefined in terms of:• Commands accepted by each sub-system,• Events generated,• Dynamical behavior (commands allowed in aparticular context, transition provoked by an event,etc.), defined using a standard graphical notation(UML state diagrams) and translated into datastructures.&DPHUD5HDG\,PDJH$FTXLVLWLRQ6XVSHQG$FTXLVLWLRQ&DPHUD(UURU6WDUW6WDUW([SRVXUH&RQWLQXH&RQW([S6XVSHQG3DXVH([S(UURU(UURUKDQGOHUStartErrorErrorAbort ContinueSuspendCamera notavailableCamera available&DPHUD(UURUV5HFRYHU\Setup6HWXS([S6HWXS$FTXLVLWLRQ&RPSOHWHG&RPSOHWHG([S(QG(QG([S(QG6KRZ6KRZ,PDJH6DYH6DYH,PDJHCompletedEndEndErrorShow/SaveSetupFigure 3: Operation Rules definition5  CONCLUSSIONSObservation sessions (with the participation ofastronomers at La Palma Island, Madrid, Lund andTrieste) have been performed using both real andsimulated telescopes, with fully satisfactory result. Evenif the prototype is at its first stage (a second version isexpected next May), it has proven to be a correctapproach for collaborative, remote astronomicalobservation.DYNACORE, and other similar projects, arecontributing to the introduction of new concepts such as‘Virtual operations room’ or ‘Virtual laboratories’ whichare going beyond traditional remote operation or recenton-line results publication on the web. They areproviding a framework for experts and instrumentscollaboration which makes possible a new approach toactivities such as Experimentation, Integration,Maintenance or Education. Applications for this systemsare not restricted to scientific environments. They can beused  in other contexts such as Industry, Space or HealthCare.6  REFERENCES[1] Dynacore homepage:  http://www.tcpsi.es/dynacore[2] Plasma prototype homepage: http://www.phys.uu.nl/~dynacore/[3] NOT telescope technical information: http://wwww.not.iac.es/new/technical/[4] TNG telescope technical information: http://www.tng.iac.es/[5] DYNACORE Requirements Specification V2.0, RefD2.1  (Available at Dynacore homepage)[6] Operation rules :(http://www.tcpsi.es/dynacore/astroDocs.html)[7] TNG model : (http://www.tcpsi.es/dynacore/astroDocs.html)[8] NOT model :(http://www.tcpsi.es/dynacore/astroDocs.html)[9] Corba homepage (http://www.corba.org)[10] OMG homepage (http://www.omg.org)485

Web-based Distributed Systems for Collaborative Remote Experiments

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