Advances In Persistent Object Systems

Proceedings of the biennial International Workshops on Persistent Object Systems.

The Ninth International Workshop on Persistent Object Systems (POS 9) took place at the SAS Radisson Hotel in Lillehammer, Norway, from 6th to 8th September 2000. Previous workshops in the series have been held in Scotland (1 and 2), Australia (3), the USA (4), Italy (5), France (6), and the USA (7 and 8). In keeping with those workshops, POS 9 was short but intensive, fitting 28 papers and panel sessions, a boat 1 excursion, and some memorable meals into two and a half days. The participants’ concentration was no doubt helped by the Northern European weather that prevailed for most of the workshop. Continuing a trend experienced over the previous few workshops, POS 9 had difficulty attracting a high number of papers. Of course it is hard to tell whether this is a problem with the field of persistent systems itself, or merely a consequence of the increasing number of workshops, conferences, and journals competing for submissions. In his Epilogue to the proceedings, Ron Morrison makes some interesting suggestions for possible improvements to future POS workshops. Out of a total of 26 submitted papers, 19 were accepted for presentation at the 2 workshop. Breaking down by region, 6 1/2 came from the USA , 1 from Africa, 3 1/2 from Australia, and 8 from Europe. In a new development for POS, an equal number of papers came from England and from Scotland.

In 1992 we initiated a research project on large scale distributed computing systems (LSDCS). It was a collaborative project involving research institutes and universities in Bologna, Grenoble, Lausanne, Lisbon, Rennes, Rocquencourt, Newcastle, and Twente. The World Wide Web had recently been developed at CERN, but its use was not yet as common place as it is today and graphical browsers had yet to be developed. It was clear to us (and to just about everyone else) that LSDCS comprising several thousands to millions of individual computer systems (nodes) would be coming into existence as a consequence both of technological advances and the demands placed by applications. We were excited about the problems of building large distributed systems, and felt that serious rethinking of many of the existing computational paradigms, algorithms, and structuring principles for distributed computing was called for. In our research proposal, we summarized the problem domain as follows: “We expect LSDCS to exhibit great diversity of node and communications capability. Nodes will range from (mobile) laptop computers, workstations to supercomputers. Whereas mobile computers may well have unreliable, low bandwidth communications to the rest of the system, other parts of the system may well possess high bandwidth communications capability. To appreciate the problems posed by the sheer scale of a system comprising thousands of nodes, we observe that such systems will be rarely functioning in their entirety.

Persistent object systems are systems which support the creation and manipulation of objects in a uniform manner, regardless of how long they persist. This is in direct contrast with conventional systems where temporary objects are created and manipulated using one mechanism (typically programming language data structures) and permanent objects are maintained using a different mechanism (usually a filestore). The unification of temporary and permanent objects yields systems which are smaller and more efficient than conventional systems and which provide a powerful and flexible platform for the development of large, data intensive applications. This volume presents the proceedings of a workshop at which latest research in this area was discussed. The papers are grouped into sections on the following topics: type systems and persistence, persistent programming languages, implementing persistence, object stores, measurement of persistent systems, transactions and persistence, and persistent machines.

With the unprecedented growth-rate at which data is being collected and stored electronically today in almost all fields of human endeavor, the efficient extraction of useful information from the data available is becoming an increasing scientific challenge and a massive economic need. This book presents thoroughly reviewed and revised full versions of papers presented at a workshop on the topic held during KDD'99 in San Diego, California, USA in August 1999 complemented by several invited chapters and a detailed introductory survey in order to provide complete coverage of the relevant issues. The contributions presented cover all major tasks in data mining including parallel and distributed mining frameworks, associations, sequences, clustering, and classification. All in all, the volume presents the state of the art in the young and dynamic field of parallel and distributed data mining methods. It will be a valuable source of reference for researchers and professionals.

These post-proceedings contain the revised versions of the papers presented at the \Symposium on Objects and Databases" which was held in Sophia-Antipolis, France, June 13, 2000, in conjunction with the Fourteenth European Conference on Object-Oriented Programming, ECOOP 2000. This event continued the t- dition established the year before in Lisbon (Portugal) with the First Workshop on Object-Oriented Databases. The goal of the symposium was to bring together researchers working in various corners of the eld of objects and databases, to discuss the current state of research in the eld and to critically evaluate existing solutions in terms of their current usage, their successes and limitations, and their potential for new applications. The organizing committee received 21 papers which were reviewed by a p- gram committee of people active in the eld of objects and databases. There were 3 reviews for each paper, and nally the organizing committee selected 9 long papers, 2 short papers, and a demonstration to be presented and discussed at the symposium. The selected papers cover a wide spectrum of topics, including data modeling concepts, persistent object languages, consistency and integrity of persistent data, storage structures, class versioning and schema evolution, query languages, and temporal object-oriented databases. In addition to the regular papers, the symposium included an invited p- sentation, given by Prof. Malcolm Atkinson from the University of Glasgow (Scotland) where he heads the Persistence and Distribution Group.