Abstract: An architecture for a memory-resident, Parallel and Persistent ObjectSTore (PPOST) is suggested. Different object-oriented databases might be built on top of PPOST. The term memory-resident (or main memory based) means that the primary storage device is main memory. Persistence is guaranteed automatically by managing secondary and stable storage devices (such as main memory with uninterrupted power supply, discs and tapes). The architecture is able to take advantage of available main memory in a parallel or distributed environment. Thus, transactions can be actually performed with memory-speed, without being limited by the size of the memory of a given computer. Such an architecture is especially advantageous for applications requiring very fast answers, such as CAD or high-performance simulation.

Abstract: We claim that distributed object-oriented systems must provide a higher level of abstraction to their users, than usually provided. Especially, it is necessary to provide application-oriented, intelligent aggregates of objects with transparent distribution of their elements. Beside that, it seems to be not only reasonable, but also relatively easy to connect persistence with distribution. A system, offering distributed and persistent polymorphic sets of objects, on the level of a clean, type safe programming language is introduced. 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 or classes of objects.

Abstract: An extension of a general-purpose programming language (gpPL) is presented. It enables parallelism, persistence and query optimization based on sets. The authors demonstrate that in gpPLs the primitive "set" can be generalised for the needs of database and expert system applications. Side-effect free declarative queries, based on set expressions, can be optimized and executed in parallel. Individual optimization and parallelization are integral parts of the language system and compiler. Very different combinations of persistent or volatile, and parallel or sequential, and optimized or non-optimized implementations are possible. This is eased by the fact that a great part of the implementation is located outside the compiler with the help of predefined interfaces. Different algebras, optimizers or algorithms can be considered. The same program can be executed without modification in various systems or platforms.

Abstract: An approach to accelerate distributed, object-oriented simulations is presented in this paper. It is based on the assumption that a higher acceleration can be achieved in an easier way, if the problem is alread tackled early at the modeling stage [STOP 95]. The user adds hints about the communication behavior and frequencies of object classes to the simulation model. Based on this information, an object graph is generated and distributed to a selected number of partitions. The distribution phase is fully automatic. As a result a distribution of the problem nearby the communication optimum is generated. In the next phase the distributed simulation program (code) is generated. In a final step the user only has to code the methods of the object classes and run the simulation. The major advantage of this approach is that the user is freed from the difficult task of finding a good distribution for the problem to be simulated, which is an important factor for the overall performance of the simulation. Another advantage is the possibility to vary model information (hints) about the communication, and get a new (quasi optimal) version of the simulation automatically generated.

Abstract: A hint-based, distributed, discrete, object-oriented simulation system is described. In course of the design phase of the simulation model, explicit hints can be provided concerning dependencies and information flow inside the model. The process of parallelization consists of two major steps. In the first step, the abstract model, enriched with user-supplied hints is mapped onto an arbitrary number of active units. In the second step, the active units are mapped onto a given number of physical nodes, characterized by their processing capacity and by the communication latency between them. The distribution scheme may be dynamic, i.e. simulation objects can change their location in course of the simulation, in order to get better performance. Klaus.Leopold 05.04.2001.

Abstract: Parallel and persistent object sets are suggested to be incorporated into general-purpose programming languages. Two alternative implementations are presented. The actual form of the proposal is an extension of Modula-3.

Abstract: Informatik in der Schule - Informatik für die Schule.

Abstract: Proceedings of the 7th Joint Conference of the Austrian Computer Society (OCG) and the John von Neumann Society for Computing Sciences (NJSZT), Klagenfurt, 1992.