G. Kemmerling

Upgrading a TEXTOR Data acquisition system for remote participation using Java and Corba

Abstract The partners in the Trilateral Euregio Cluster (TEC) are implementing and developing Remote Participation technologies that are expected to support a joint research programme on the experimental facility TEXTOR-94. A common TEC architecture for our heterogeneous data acquisition and storage systems is seen to be one of the major issues. As a consequence, legacy systems will be affected and have to be upgraded for optimised wide area network communication, platform independent data access and display. The object oriented redesign of the system to be described follows theses guidelines. The architecture of the system under development uses Java as programming environment and CORBA as Client/Server communication standard. It is described in this paper, how an operational Data Acquisition CAMAC subsystem of TEXTOR-94 based on OpenVMS and Decnet communications could be redesigned into an open, object oriented architecture in a platform independent way. A suitable Web Browser is required on the client side without further installation of application software to run the server. CORBA static method invocations are used for the communication between the client and server. At the server side, there is only Java code on top of the existing commercial OpenVMS CAMAC device driver. A modular object oriented software design permitted to eliminate dependencies of the generic module levels from the underlying bus systems. Porting of the Java code to other platforms like Windows NT and Linux has proven to be successful.

Remote handling of TEXTOR diagnostics using CORBA as communication architecture

Abstract At the Forschungszentrum Julich, an upgrade of the existing distributed system for data acquisition (DAS) at the fusion experiment TEXTOR94 is under development. DAS is currently restricted to VAX/VMS and DECNET based communications, but it is planned to add UNIX based systems, and to open the local network for an improved wide area network access for remote operations. Therefore, the DAS system is to be equipped with a suitable client/server interface, which is able to cope with the various computer platforms and operating systems involved. For this purpose, the common object request broker architecture (CORBA) will be used. CORBA is an object oriented, standardized architecture for distributed systems, which provides a high degree of modularity in software design and allows for flexible implementations. It is to act as a connecting link between the existing system and new extensions. In order to provide the desired client/server functionality for the data acquisition tasks, the components of the system (diagnostic, database, etc.) are modelled by CORBA interfaces. Processes for diagnostic control and data readout in the existing OpenVMS systems are aimed at to be accessible by CORBA server implementations. The corresponding client implementations will be developed for the operating system platforms most frequently used at TEXTOR94. Communication between clients and server will be based on TCP/IP and are to be managed by CORBA. By this standardized way, remote control of diagnostic instrumentation becomes possible in a multiplatform computer and wide area network environment. At a later stage it is intended to integrate the system into a ‘virtual control room’ environment, which should enable the participation of cooperating institutions in the full experimental program of TEXTOR94.

Development of an integrated data storage and retrieval system for TEC

The database system for the storage and retrieval of experimental and technical data at TEXTOR-94 has to be revised. A new database has to be developed, which complies with future performance and multiplatform requirements. The concept, to be presented here, is based on the commercial object database Objectivity. Objectivity allows a flexible object oriented data design and is able to cope with the large amount of data, which is expected to be about 1 TByte per year. Furthermore, it offers the possibility of data distribution over several hosts. Thus, parallel data storage from the frontend to the database is possible and can be used to achieve the required storage performance of 200 MByte per min. In order to store configurational and experimental data, an object model is under design. It is aimed at describing the device specific information and the acquired data in a common way such that different aproaches for data access may be applied. There are several methods forseen for remote access. In addition to the C++ and Java interfaces already included in Objectivity/DB, CORBA and socket based C interfaces are currently under development. This could also allow an access by non-supported platforms and enable existing legacy applications an integration of the database for storage and retrieval of data by a minimum of code changes.

The TEC remote control room project at TEXTOR

a FOM Instituut 6oor Plasmafysica Rijnhuizen, EURATOM Association, Postbus 1207, Edisonbaan 14, 3430 BE Nieuwegein, The Netherlands b Laboratoire de Physique des Plasmas/Laboratorium 6oor Plasmafysica, ERM/KMS, EURATOM Association, B-1000 Brussels, Belgium c Institut für Plasmaphysik, Forschungszentrum Jülich GmbH, EURATOM Association, D-52425 Jülich, Germany d Werkgroep Fysische Informatica, Faculty of Physics and Astronomy, Utrecht Uni6ersity, Utrecht, The Netherlands e Zentrallabor für Elektronik, Forschungszentrum Jülich GmbH, EURATOM Association, D-52425 Jülich, Germany

Virtual control room, the REMOT project, networking pilot studies

The Remote Experiment Monitoring and Control (REMOT) project objective is to develop a system architecture to allow remote control of scientific experiments and facilities that require real time operation and multimedia information feedback, using available or deploying communications infrastructure. Representatives from two user communities participate in the project: the astronomical community, which usually has telescopes located at far places-such as islands and/or mountains- and the plasma physics community, that is concentrating the experimental facilities in a few places in order to save costs. In this paper we review the underlying networking technologies considered, and summarize the results on the ATM based pilot studies we have carried out in the last two years. Particularly we present results from experiments on Switched Virtual Circuits (SNC) tunneling and video on ATM.

A software architecture for remote participation at the Textor-94 experiment

Abstract The Trilateral Euregio Cluster (TEC) is a collaboration between three plasma-physics institutes: the Laboratory for Plasma Physics at the Koninklijke Militaire School (KMS) in Brussels, Belgium, the FOM Institute for Plasma Physics in Rijnhuizen, the Netherlands and the Institute for Plasma Physics at the Forschungszentrum Julich (FZJ) in Germany. They jointly perform nuclear fusion experiments at the tokamak reactor ‘Textor-94’ in Julich. Currently, scientists from FOM and KMS have to be physically present at the Textor-94 control room to participate in experiments. To show that remote participation is feasible, the Dynacore project built a software demonstrator that allows scientists to view measurement data, control measurement equipment and view the status of Textor-94. The demonstrator uses Java applets as clients, C ++ servers, and CORBA for communication. The chosen architecture has the following advantages. It is portable, modular and reusable, eases collaboration in software development and optimizes for performance over the Internet. We solved the problems we had with applet security policies, the performance of our design and the integration of legacy systems. Our demonstrator shows that remote participation is feasible. The reactions from potential users are very positive. However, the demonstrator has to be improved for real usage in the future.

A distributed plasma physics experiment system using CORBA

In the framework of the EU-funded Dynacore project an experiment system using a scalable and object-oriented architecture will be built. The system will be component-based and can be extended with little effort by the end-users. It will allow experiments to be monitored and controlled in real time over wide area (Internet) links. The data produced by the experiments will be accessible from any given location that has Internet connectivity available. CORBA will be used as the basic plumbing for component interaction. This allows all components in the system to interact in a well-defined way through interfaces defined in IDL, while allowing each component to be implemented using the ORB and platform most suited for the job. Since not all implementations of CORBA provide the possibility of secure connections, options for encryption of the data streams between clients and servers outside of software control are needed. Some schemes for hardware encryption inside routers and/or switches are under investigation. For the actual data storage, objectivity will be used because its object-oriented nature fits well in the whole framework and because it is capable of handling the amounts of data that will typically be produced in a plasma physics experiment (a Terabyte per year).

Objectivity/Corba distributed database performance on a gigabit Sun-ultra-10 cluster

Dynacores project objective is to provide tools for the remote operation of large physics experiments. Our group concentrates on the design of a remote control room for the Textor-94 plasma-physics experiment, which will incorporate a distributed database, accessible with Corba over Internet. During normal operation, Textor-94 generates hundreds of megabytes of measurement data within the few seconds of a plasma shot. These shots are generated approximately every ten minutes, in total around 30 shots per day. A database will make the measurement data available to scientists, both at the experiment and in remote control rooms, which can be located in different countries, within minutes after the acquisition. Fast access to the database and a high data-storage speed are, therefore, of utmost importance. We have defined a set of data objects, which allow storage of virtually any kind of Textor measurement data. An Objectivity object-oriented database is used to store these objects. We have also designed an architecture in which database clients access the measurement database solely via data managers with Corba-interfaces. The data managers introduce security into the database, and also hide details of the database implementation for the users. An object manager provides clients with a central starting point, and distributes the total database load in an intelligent way over all available data-managers.