Semantic Web and Peer-to-Peer SteffenStaab·HeinerStuckenschmidt(Eds.) Semantic Web and Peer-to-Peer Decentralized Management and Exchange of Knowledge and Information With 89 Figures and 15 Tables 123 Editors Steffen Staab University of Koblenz Institute for Computer Science Universitaetsstr. 1 56016 Koblenz, Germany [email protected] Heiner Stuckenschmidt University of Mannheim Institute for Practical Computer Science A5, 6 68159 Mannheim, Germany [email protected] Library of Congress Control Number: 2005936055 ACM Computing Classification (1998): C.2.4, H.3, I.2.4 ISBN-10 3-540-28346-3 Springer Berlin Heidelberg New York ISBN-13 978-3-540-28346-1 Springer Berlin Heidelberg New York This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilm or in any other way, and storage in data banks. Duplication of this publication or parts thereof is permitted only under the provisions of the German Copyright Law of September 9, 1965, in its current version, and permission for use must always be obtained from Springer. Violations are liable for prosecution under the German Copyright Law. Springer is a part of Springer Science+Business Media springeronline.com © Springer-Verlag Berlin Heidelberg 2006 Printed in Germany The use of general descriptive names, registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant pro- tective laws and regulations and therefore free for general use. Typeset by the authors using a Springer TEX macro package Production: LE-TEXJelonek,Schmidt&VöcklerGbR,Leipzig Cover design: KünkelLopka Werbeagentur, Heidelberg Printed on acid-free paper 45/3142/YL - 543210 To our families Preface The Semantic Web and Peer-to-Peer are two technologies that address a common need at different levels: • The Semantic Web addresses the requirement that one may model, manipulate and query knowledge and information at the conceptual level rather than at the level of some technical implementation. Moreover, it pursues this objective in a way that allows people from all over the world to relate their own view to this conceptual layer. Thus, the Semantic Web brings new degrees of freedom for changing and exchanging the conceptual layer of applications. • Peer-to-Peer technologies aim at abandoning centralized control in favor of de- centralized organization principles. In this objective they bring new degrees of freedom for changing information architectures and exchanging information be- tween different nodes in a network. • Together, Semantic Web and Peer-to-Peer allow for combined flexibility at the level of information structuring and distribution. Historical Remarks and Acknowledgements How to benefit from this combined flexibility has been investigated in a number of research efforts. In particular, we coordinated the EU IST research project “SWAP — Semantic Web and Peer-to-peer” (http://swap.semanticweb.org) that led to many chapters of this book1 and, also, to a 15,000 Euro doIT software innova- tion award for the work on Bibster (see Chap. 18) from the local government of the German state of Baden-Württemberg. Thus, we are very much indebted to the EU for generously funding this project. Obviously this book contains many other chapters — and for very good reasons: First, we profited enormously from tight interaction with colleagues in other projects, such as the Italian-funded project Edamok (Fausto Giunchiglia, Paolo Bouquet, Mat- teo Bonifacio and colleagues) and the German-funded project Edutella (Wolfgang Nejdl and colleagues) — just to name the two most influential, as we cannot name 1 Chapters 1,5,6,7,11,14,15,17,18. VIII Preface all the giants on the shoulders of whom we stand. Second, though we could have easily filled all the pages of a thick book just with research contributions from the SWAP project, it was not our primary goal to do a book “on SWAP”, but a book on the “Semantic Web and Peer-to-Peer” and the many different aspects that this con- junction brings along. This, clearly, fell outside of the possibilities of SWAP, but it was easily possible with the help of many colleagues who worked on shaping the joint area of Semantic Web and Peer-to-Peer. We thank all of these numerous colleagues within SWAP and outside. Special thanks go to Thomas Franz for integrating the contributions into a common LATEX document. Purpose of This Book It is the purpose of this book to acquaint the reader with the needs of joint Semantic Web and Peer-to-Peer methods and applications, in particular in the area of infor- mation sharing and knowledge management where we see their immediate use and benefit. For this purpose, we start with an elaborate introduction to the overall topic of this book. The introduction surveys the topic and its subtopics, represented by four major parts of this book, and briefly sorts all individual contributions into a global perspective. The global perspective is refined in an introductory section at the begin- ning of each part. In the core of the book, the contributions discuss major aspects of Semantic Web and Peer-to-Peer-based systems, including parts on: 1. Data storage and access; 2. Querying the network; 3. Semantic integration; and 4. Methodologies and applications. Together these contributions shape the picture of a comprehensive lifecycle of applications built on Semantic Web and Peer-to-Peer. Its success stories include high flying applications, such as applications for knowledge management like KEx (Chap. 16), for knowledge sharing in virtual organizations (cf. Xarop in Chap. 17) as well as for information sharing in a global community (cf. Bibster in Chap. 18). The Future of Semantic Web and Peer-to-Peer We see a far-ranging future for Semantic Web and Peer-to-Peer technologies. Indus- try discovers P2P technologies not just for document-oriented information sharing, but also for recent communication channels like voice-over-IP (internet telephony) or instant messaging. At the same time the need to structure communication and in- formation content from many channels and information repositories grows further and underlines the need for the combined technologies of Semantic Web and Peer- to-Peer. Recent research efforts target and extend this area from the perspective of social networks and semantic desktops and we expect a lot of impetus from this Preface IX work. Web services and Grid infrastructures rely on Peer-to-Peer service communi- cation and the only way to discover appropriate services and exchange meaningful content is to join Semantic Web and Peer-to-Peer. Hence, we invite you to ride the first wave of Semantic Web and Peer-to-Peer here in this book. The next big one is sure to come. June 2006 Steffen Staab, Koblenz, Germany Heiner Stuckenschmidt, Amsterdam, The Netherlands Contents Peer-to-Peer and Semantic Web Heiner Stuckenschmidt, Frank van Harmelen, Wolf Siberski, Steffen Staab .... 1 Part I Data Storage and Access Overview: Data Storage and Access Heiner Stuckenschmidt ............................................. 21 1 An RDF Query and Transformation Language Jeen Broekstra, Arjohn Kampman .................................... 23 2 RDF and Traditional Query Architectures Richard Vdovjak, Geert-Jan Houben, Heiner Stuckenschmidt, Ad Aerts ....... 41 3 Query Processing in RDF/S-Based P2P Database Systems George Kokkinidis, Lefteris Sidirourgos, Vassilis Christophides ............. 59 Part II Querying the Network Overview: Querying the Network Steffen Staab ..................................................... 85 4 Cayley DHTs—AGroup-Theoretic Framework for Analyzing DHTs Based on Cayley Graphs Changtao Qu, Wolfgang Nejdl, Matthias Kriesell ........................ 89 5 Semantic Query Routing in Unstructured Networks Using Social Metaphors Christoph Tempich, Steffen Staab ....................................107 XII Contents 6 Expertise-Based Peer Selection Ronny Siebes, Peter Haase, Frank van Harmelen ........................125 7 Personalized Information Access in a Bibliographic Peer-to-Peer System Peter Haase, Marc Ehrig, Andreas Hotho, Björn Schnizler .................143 8 Designing Semantic Publish/Subscribe Networks Using Super-Peers Paul-Alexandru Chirita, Stratos Idreos, Manolis Koubarakis, Wolfgang Nejdl ..159 Part III Semantic Integration Overview: Semantic Integration Heiner Stuckenschmidt .............................................183 9 Semantic Coordination of Heterogeneous Classifications Schemas Paolo Bouquet, Luciano Serafini, Stefano Zanobini .......................185 10 Semantic Mapping by Approximation Zharko Aleksovski, Warner ten Kate ...................................201 11 Satisficing Ontology Mapping Marc Ehrig, Steffen Staab ...........................................217 12 Scalable, Peer-Based Mediation Across XML Schemas and Ontologies Zachary G. Ives, Alon Y. Halevy, Peter Mork, Igor Tatarinov ...............235 13 Semantic Gossiping: Fostering Semantic Interoperability in Peer Data Management Systems Karl Aberer, Philippe Cudré-Mauroux, Manfred Hauswirth ................259 Part IV Methodology and Systems Overview: Methodology and Systems Steffen Staab .....................................................279 14 A Methodology for Distributed Knowledge Management Using Ontologies and Peer-to-Peer Peter Mika .......................................................283