Abstract: This paper describes the PARMED project initiative The aim of PARMED is to provide medical stu with a large virtual database of image and video data distributed over several medical centers Clients can access the PARMED system by an active client software which provides graphical interfaces to query the virtual database Incoming video streams and image data is postprocessed by the active client software to allow analysis of this data for diagnostics or virtual teaching Quality of service and security aspects are crucial for such kind of distributed system and will be addressed with priority

Abstract: Diverging demands on computer networks, such as high bandwidth, guaranteed quality of service and low latency lead to growing heterogeneity. IEEE1394-1995 is a standardized low-cost highperformance serial-bus-system with both isochronous and asynchronous operation. It might be an interesting candidate for all-round local and system area networks, providing a good compromise in fulfilling the above demands for low costs. Beside providing some technical background we show the possibilities and advantages of building parallel clusters on top of IEEE1394-1995. The main advantage is that minimal speed-up can be guaranteed, as shown on the basis of the parallel implementation of discrete Fourier transformation.

Abstract: An approach is introduced for semi-automatic parallelization of object-oriented simulations. The basic idea is to prepare parallelization at the earliest possible stage in the life-cycle of the creation of new simulations (i.e. at modeling), thus minimizing causality conflicts at run-time. The object-oriented model of a simulation is enriched by hints, describing the estimated load and communication costs between major classes and objects. This helps to grasp the inherent parallelism of the model. Based on this additional information, a partitioning with minimal communication between partitions can be generated automatically. Remaining dependency-conflicts must be resolved at run-time. The GoSim [A. Stopper, GoSim, ein Ansatz zur Beschleunigung diskreter, objektorientierter, verteilter Simulationen, Ph.D. Thesis, Institute of Informatics, University Klagenfurt, 1997] simulation system is presented, which implements the described proposal and provides semi-automatic parallelization of large-scale and/or high-performance simulations. It provides a description language, a partitioning tool, a program-skeleton generator and a simulation engine. Some measurements prove the usability of the approach.

Abstract: A method for evaluating several aspects of the performance of object oriented middleware is introduced. Latency, data transfer, parameter marshalling and scalability are considered. A portable benchmark toolkit has been developed to implement the method. A number of actual middleware products have been measured, such as C++ and Java based CORBA implementations, DCOM and Java/RMI. The measurements are evaluated and related to each other.

Abstract: This book constitutes the joint refereed post-proceedings of 20 workshops, one panel session, and one poster session held during the 13th European Conference on Object-Oriented Programming, ECOOP'99, in Lisbon, Portugal in June 1999. The volume presents overviews of the 20 workshops as well as more than 200 individual short presentations by the contributing authors in a coherent and systematic way. The wealth of up-to-date information provided spans the whole spectrum of object technology, from theoretical and foundational issues to applications in various domains.

Abstract: Aliasing in Object-Oriented Systems.

Abstract: This paper describes the design of a common message passing layer for implementing both MPI and PVM over the SCI interconnect in a workstation or PC cluster. The design is focused at obtaining low latency. The message layer encapsulates all necessary knowledge of the underlying interconnect and operating system. Yet, we claim that it can be used to implement such different message passing libraries as MPI and PVM without sacrificing efficiency. Initial results obtained from using the message layer in SCI clusters are presented.

Abstract: This short paper presents a system offering parallel persistent and polymorphic sets of objects, on the level of an existing general purpose object-oriented programming language, like Modula-3 and JAVA. The user of such a system gets distribution and persistence in the same natural way, as users of traditional systems get volatile arrays of numbers of objects. In addition, advantages are taken from sophisticated optimization techniques.

Abstract: Even the more or less "canonical'', lower-level architecture of information systems needs to be revisited from time to time. Notions like persistence and transactions belong traditionally to the area of database management systems. There are, however, many applications, such as CAD, VLSI design or simulation, which need persistence and could take advantage of transactions, but require especially fast implementations not provided by DBMS. In this paper we are describing a low-level transaction concept used to implement our parallel main memory object store (PPOST), to provide main memory access times combined with the safety and convenience of transactions.

Abstract: The choice of the first-course programming language for a university-level computer science curriculum has pedagogical ramifications in terms of comprehensibility and mastery of fundamental concepts. This paper compares the merits of Java and Modula-3 as a first-course language.

Abstract: Dieses Papier gibt eine allgemeine Einführung in Threads und vergleicht einige derzeit für Arbeitsplatzrechner erhältliche Thread-Systeme. Aufbauend auf einer Motivation und grundlegenden Erläuterung des Thread-Konzepts werden wichtige Aspekte und Probleme von Thread-Bibliotheken vorgestellt. Nach einigen Hinweisen zur Programmierung mit Threads werden mehrere Implementierungen einander gegenübergestellt.

Abstract: Due to their excellent cost/performance ratio, clusters of PCs can be attractive high-performance computing (HPC) platforms. Yet, their limited communication performance over standard LANs is still prohibitive for parallel applications. The project "Shared Memory in a LAN-like Environment" (SMiLE) at LRR-TUM adopts Scalable Coherent Interface (SCI) interconnect technology to build, and provide software for, a PC cluster which, with hardware-based distributed shared memory (DSM) and high-performance communication characteristics, is regarded as well suited for HPC. The paper describes the key features of the enabling technology, SCI. It then discusses the developments and important results of the SMiLE project so far: the development and initial performance of a PCI/SCI interface card, and the design and initial performance results of low-latency communication layers, Active Messages and a sockets emulation library.

Abstract: Low latencies for small messages are an important factor of efficient fine-grained parallel computation. The Active Messages concept provides this minimal overhead by eliminating certain parts of the critical path of sending and receiving messages, that is the context switch into the operating system kernel when using user-mode I/O, and multiple buffering in the network layer. Hardware-supported distributed shared memory (DSM) architectures exhibit various properties that make them particularly useful for an implementation of the aforementioned messaging mechanisms. This paper thus describes the concept, implementation, and the performance of a DSM-based Active Messages layer.

Abstract: To enable the efficient utilization of clusters of workstations it is crucial to develop a stable and rich software infrastructure. The ESPRIT Project SISCI will provide two widely used message-passing interfaces, MPI and PVM, as well as a POSIX compliant, distributed thread package (Pthreads) on multiple SCI-based clusters. This paper features motivation and background on this projects as well as details of the two core components: the common messaging layer and the Pthreads package.

Abstract: Active Messages haben sich als effizientes Kommunikationsverfahren insbesondere auf Kommunikationstechnologien durchgesetzt, die einen direkten Zugriff des Benutzers ohne Intervention des Betriebssystems zulassen. Als Nachteil der leichtgewichtigen Kommunikation erwiesen sich jedoch die nicht ausreichenden Schutzmechanismen, vor allem bei der Verwendung mehrerer Prozesse, die sich gleichzeitig einer Active-Message-Bibliothek bedienen. Die Spezifikation 2.0 der Berkeley-Active-Messages unternimmt nun den Versuch, f¨ur das bekannte und schnelle Kommunikationsverfahren Schutzabstraktionen vorzusehen. Im Rahmen dieser Arbeit wird die Implementation eines solchen Active-Message-Layers der Version 2.0 auf einem Cluster von SCI-gekoppelten Arbeitsplatzrechnern beschrieben. Wir k¨onnen zeigen, daß die zus¨atzlichen Schutzmechanismen nur wenig Einfluß auf die Leistung haben und somit der Vorteil der Active Messages, die leichtgewichtige, feingranulare Kommunikation, erhalten bleibt.

Abstract: Active Messages haben sich als effizientes Kommunikationsverfahren insbesondere auf Kommunikationstechnologien durchgesetzt, die einen direkten Zugriff des Benutzers ohne Intervention des Betriebssystems zulassen. Als Nachteil der leichtgewichtigen Kommunikation erwiesen sich jedoch die nicht ausreichenden Schutzmechanismen, vor allem bei der Verwendung mehrerer Prozesse, die sich gleichzeitig einer Active-Message- Bibliothek bedienen. Die Spezifikation 2.0 der Berkeley-Active-Messages unternimmt nun den Versuch, für das bekannte und schnelle Kommunikationsverfahren Schutzabstraktionen vorzusehen. Im Rahmen dieser Arbeit wird die Implementation eines solchen Active- Message-Layers der Version 2.0 auf einem Cluster von SCI-gekoppelten Arbeitsplatzrechnern beschreiben. Wir können zeigen, daß die zusätzlichen Schutzmechanismen nur wenig Einfluß auf die Leistung haben und somit der Vorteil der Active Messages, die leichtgewichtige, feingranulare Kommunikation, erhalten bleibt.

Abstract: Choosing the "First Computer Language" is still a crucial issue. While the debate is quite often conducted on the language level, the arguments for making the choice are rather of much deeper methodological, didactical, and non-technical nature. Here, we describe the decision process that lead us to choose Modula-3 as the first language to be taught to informatics students at the Universität Klagenfurt and report on the experience gained.