Michael Gesmann

A remote cooperation system supporting interoperability in heterogeneous environments

Federated database systems are heterogeneous with respect to data models and query languages but also with respect to underlying operating systems and hardware platforms. Besides transformations on the semantics level conversions on the data representation and communication protocol level have to be done. The authors present the Remote Cooperation System RCS which provides client/server communication procedures independent of hardware and operating system aspects. Thus, the configuration of a system may change without affecting the participating databases and application tools. The RCS allows for asynchronous service invocation, thus enabling the simultaneous querying of several databases by one application. Furthermore, it supports multi-tasking of server processes and the element-wise transfer of results. Monitoring tools allow the assessment of several choices in system configuration and access algorithms embodied in the application processes.<<ETX>>

Mapping a Parallel Complex-Object DBMS to Operating System Processes

So far, parallelism in complexobject and object-oriented DBMS has not been investigated in depth because descriptive and set-oriented query languages did not exist for these systems. However, with standardization of OQL by ODMG or SQL3 by ANSI, systems implementing these languages are ready to exploit parallel query processing strategies. In this paper, we explain differences between parallel query processing in relational and complex-object DBMS. Furthermore, we present a client/server-based system architecture that allows for fine-grained parallelism within query processing in complex-object DBMS. We investigate various strategies for mapping this architecture to processes of the underlying operating system. Finally, some measurements show the impact of these mapping strategies on query response times.

A Cost Model for Parallel Navigational Access in Complex-Object DBMSs

In contrast to relational query processing, one of the most important extensions of query processing in object-oriented DBMSs (OODBMSs) is navigational access to objects. So far, optimization of this kind of access has been primarily supported by special access path structures or object clustering strategies. Parallelism, although an important topic in large relational systems, has not been explored comprehensively in OODBMSs. In order to evaluate parallel access strategies when collecting a set of objects, we present a cost model to estimate the necessary amount of page I/O. In contrast to others, our cost model covers parallel execution of navigational retrieval operations under a restricted number of available buffer frames. Finally, some measurements validate the cost model.

Performance evaluation of the Remote Cooperation System in PRIMA

In order to achieve acceptable performance in enhanced DBMS, different kinds of parallelism have to be enabled by appropriate implementation capabilities. The Remote Cooperation System (RCS) offers these capabilities. It is the basic communication system of an enhanced DBMS called PRIMA. We present different implementations for RCS and an analysis of their performance behavior. In order to get a better assessment of these implementations, we compare our measurements to those obtained with conventional remote procedure call facilities offered by operating systems. The results demonstrate that RCS is suitable for supporting parallel query execution.<<ETX>>

PRIMA - a database system supporting dynamically defined composite objects

PRIMA is a non-standard database system developed at the University Kaiserslautern. Its major purpose is the support of engineering design applications, such as VLSI design and software engineering. The applications require tailored application-dependent interfaces which, however, all share basic notions like that of a composite object. Hence, the approach of PRIMA is to offer an application-independent complex-object interface (the moleculeatom data model, shortly called MAD model) and to provide means to easily augment this interface by application-dependent functionality. In the following, we will concentrate on the MAD model and its implementation.

Messen und Bewerten paralleler Client/Server-Architekturen - am Beispiel des kooperierenden Non-Standard-Datenbanksystems PRIMA

Mit der stetigen Verbreitung und Vernetzung von Arbeitsplatzrechnern sowie dem wachsenden Einsatz von Mehrrechnersystemen gewinnen auftragsorientierte Systemmodelle, die eine Zerlegung in auftraggebende und auftragnehmende Systemkomponenten vorsehen, zunehmend an Bedeutung. Die effektive Nutzung der verteilten Rechnerleistung erfordert geeignete Masnahmen zur Unterstutzung der parallelen Auftragsabwicklung. Neben Konzepten zur Betriebssystemeinbettung adaquater Ablaufumgebungen existiert ein Bedarf an Mesweikzeugen und Analysemethoden, die eine quantifizierbare Bewertung paralleler, auftragsorientierter Anwendungssysteme erlauben.