Semantic Web and Peer-to-Peer - Decentralized Management and Exchange of Knowledge and Information

Preface

Contents

Peer-to-Peer and Semantic Web

1 The Semantic Web

1.1 Infrastructure for Machine-Readable Metadata

1.2 Representing Local and Shared Meaning

2 Peer-to-Peer

2.1 Peer-to-Peer and Knowledge Management

2.2 Peer-to-Peer and the (Semantic) Web

3 Aspects of Semantics-Based Peer-to-Peer Systems

3.1 Data Storage and Access

3.2 Querying the Network

3.3 Integration Mechanism

3.4 Building and Maintaining Semantic P2P Applications

3.5 Other Issues

4 Conclusions

References

Part I Data Storage and Access

Overview: Data Storage and Access

1 An RDF Query and Transformation Language

1.1 Introduction

1.2 Query Language requirements

1.2.1 Expressive power

1.2.2 Schema awareness

1.2.3 Program manipulation

1.2.4 Compositionality

1.2.5 Semantics

1.3 The Syntax of SeRQL

1.3.1 Path Expressions

1.3.2 Filters and operators

1.4 Formal Interpretation of SeRQL

1.4.1 Mapping Basic Path Expressions to Sets

1.4.2 Functions

1.4.3 Reducing Composed Expressions

1.5 Related work

1.6 Conclusions

References

2 RDF and Traditional Query Architectures

2.1 Introduction

2.2 Motivation

2.3 Hierarchical mediator architecture

2.3.1 Indexing Sources

2.3.2 Index Creation and Maintenance

2.3.3 Query Planning and Optimization

2.3.4 Object Identity

2.3.5 HMA Advantages and Limitations

2.4 Cooperative Mediator Architecture

2.4.1 Paradigm Shift

2.4.2 Query Processing and Query Optimization

2.4.3 Making the Query Plan Robust

2.5 Summary and Discussion

References

3 Query Processing in RDF/S-Based P2P Database Systems

3.1 Introduction

3.2 The SQPeer Middleware

3.2.1 RDF/S-based P2P databases and RQL Queries

3.2.2 RVL Advertisements of Peer Bases

3.2.3 Query Routing and Fragmentation

3.2.4 Query Planning and Execution

3.2.5 Query Optimization

3.3 P2P Architectures and SQPeer

3.3.1 Hybrid P2P SONs

3.3.2 Structured P2P SONs

3.4 Related Work

3.5 Summary

References

Part II Querying the Network

Overview: Querying the Network

4 Cayley DHTs - A Group-Theoretic Framework for Analyzing DHTs Based on Cayley Graphs

4.1 DHTs and Static DHT Topologies

4.2 Cayley DHTs - A Group-Theoretic Model for Analyzing DHTs

4.2.1 Groups and Cayley Graphs

4.2.2 Non-constant Degree Cayley DHTs

4.2.3 Constant Degree Cayley DHTs

4.2.4 Non-Cayley DHTs

4.3 Cayley Graph Properties and DHTs

4.3.1 Symmetry and Load Balancing

4.3.2 Hierarchy, Fault Tolerance, and Proximity

4.3.3 Connectivity and Fault Tolerance

4.3.4 Hamiltonicity and Cyclic Routing

4.4 Discussion and Related Work

4.5 Conclusions

References

5 Semantic Query Routing in Unstructured Networks Using Social Metaphors

5.1 Introduction

5.2 SWAP Platform

5.2.1 Meta-information

5.2.2 Querying for Data

5.3 Algorithm

5.3.1 The Social Metaphors

5.3.2 Protocol Scenario

5.3.3 Peer selection algorithm

5.4 Evaluation Setting

5.4.1 Data Source and Peer setup

5.4.2 Generation of queries in experiment

5.4.3 Initial con.guration of the Peer-to-Peer network simulation

5.4.4 Evaluation measures

5.5 Results

5.5.1 Hypotheses

5.5.2 Evaluation

5.6 Related Work

5.7 Conclusion

References

6 Expertise-Based Peer Selection

6.1 Introduction

6.2 Related Work on Semantic Overlay Networks

6.3 A Model for Expertise Based Peer Selection

6.3.1 Semantic Description of Expertise

6.3.2 Matching and Peer Selection

6.3.3 Semantic Overlay

6.4 Expertise Based Peer Selection in Bibster

6.5 Results of Simulation Experiments

6.6 Results of Field Study

6.7 Comparison with Results from Simulation Experiments

6.8 Conclusion

References

7 Personalized Information Access in a Bibliographic Peer-to-Peer System

7.1 Introduction

7.1.1 Example Scenarios

7.2 Ontology Based Similarity

7.2.1 The Bibliographic Ontologies

7.2.2 Semantic Similarity

7.3 Semantic User Profile

7.3.1 User Profile Representation

7.3.2 Initial User Profile and Profile Adaptation

7.4 Recommender Functions

7.4.1 Recommending Similar Items

7.4.2 Recommending Potentially Relevant Items

7.4.3 Recommending Similar Peers

7.5 Related Work

7.6 Conclusion

References

8 Designing Semantic Publish/Subscribe Networks Using Super-Peers

8.1 Introduction

8.2 A Formalism for Pub/Sub Systems Based on RDF

8.3 The Super-Peer Architecture

8.4 Processing Advertisements, Subscriptions and Notifications

8.4.1 Processing Advertisements

8.4.2 Processing Subscriptions

8.4.3 Processing Notifications

8.5 Dynamics of P2P Pub/Sub Networks

8.5.1 Of.ine Noti.cations and Rendezvous at Super-Peers

8.5.2 Peer Authentication

8.6 Related Work

8.7 Conclusions

8.8 Acknowledgements

References

Part III Semantic Integration

Overview: Semantic Integration

9 Semantic Coordination of Heterogeneous Classifications Schemas

9.1 Introduction

9.2 Our Approach

9.3 The Algorithm:

9.3.1 Semantic Elicitation

9.3.2 Semantic Comparison

9.4 Related Work

9.5 Conclusions

References

10 Semantic Mapping by Approximation

10.1 Introduction

10.2 Application in Peer-to-Peer

10.3 Internet Music Schemas

10.4 Approximate Matching

10.4.1 Normal Forms

10.5 Experiment with Approximate Matching

10.5.1 Example of an Approximate Matching

10.5.2 Comparison with Instance Data

10.6 Future Work

10.6.1 Improvements of Approximation Accuracy

10.6.2 Sources of Background Knowledge

10.7 Conclusion

Acknowledgements

References

11 Satisficing Ontology Mapping

11.1 Introduction

11.2 Terminology

11.2.1 Ontology

11.2.2 Mapping

11.2.3 Example

11.3 Process

1. Feature engineering

2. Selection of Next Search Steps.

3. Similarity Computation

4. Similarity Aggregation.

5. Interpretation

6. Iteration.

11.4 A Toolbox of Data Structures and Methods

11.4.1 Features of Ontological Entities

11.4.2 Similarity Computation

11.4.3 Similarity Aggregation

11.4.4 Interpretation

11.5 Approaches to Determine Mappings

11.5.1 Standard Mapping Approaches

11.5.2 QOM - Quick Ontology Mapping

11.6 Comparing Run-time Complexity

11.7 Empirical Evaluation and Results

11.7.1 Test Scenario Metrics

11.7.2 Results and Discussion

11.8 Related Work

11.9 Conclusion

References

12 Scalable, Peer-Based Mediation Across XML Schemas and Ontologies

12.1 Introduction

12.2 System Overview

12.2.1 Data, Schemas, and Queries

12.2.2 Data Sharing and Mediation

12.2.3 Query Processing

12.3 Mapping Requirements for Structured Data

12.4 Schema Mappings in Piazza

12.4.1 Mapping Language and Examples

12.4.2 Semantics of Mappings

12.4.3 Discussion

12.5 Query Answering Algorithm

12.5.1 Query Representation

12.5.2 The Rewriting Algorithm

12.6 Conclusions and Future Work

References

13 Semantic Gossiping: Fostering Semantic Interoperability in Peer Data Management Systems

13.1 Introduction

13.2 Motivation: Sharing Images Meaningfully

13.3 Of Semantic Neighborhoods and Schema Translations

13.4 Semantic Query Routing

13.4.1 Syntactic Measures

13.4.2 Semantic Measures

13.4.3 An illustrating example

13.5 Self-Healing Semantic Networks

13.6 Analyzing Semantic Interoperability in the Large

13.7 GridVine: Implementing Semantic Gossiping on top of a DHT

13.8 Conclusions

References

Part IV Methodology and Systems

Overview: Methodology and Systems

References

14 A Methodology for Distributed Knowledge Management Using Ontologies and Peer-to-Peer

14.1 Introduction

14.2 The Theory of Distributed Knowledge Management

14.3 Methods for Distributed Knowledge Management

14.4 Tools for Distributed Knowledge Management

14.4.1 Analysis

14.4.2 Design

14.4.3 Deployment

14.4.4 Evaluation

14.5 Summary

References

15 Distributed Engineering of Ontologies (DILIGENT)

15.1 Introduction and Motivation

15.2 DILIGENT Process

15.3 AIFB Case Study: An Argumentation Framework for DILIGENT

15.3.1 Threads of Arguments

15.3.2 Hypothesis

15.3.3 Hypothesis Validation

15.4 IBIT Case Study: a running DILIGENT Process

15.4.1 Organizational Setting

15.4.2 Technical Setting

15.4.3 Realizing a DILIGENT Process

15.4.4 Lessons Learned from the Realization

15.4.5 Tool Support for DILIGENT Steps

15.5 Related Work

15.6 Conclusion

References

16 A Peer-to-Peer Solution for Distributed Knowledge Management

16.1 Introduction

16.2 KEx: a P2P Architecture for DKM

16.2.1 K-peers

16.2.2 Roles of K-peers in KEx

16.2.3 K-Services

16.3 Development Framework

16.4 Conclusions and Research Issues

References

17 Xarop, a Semantic Peer-to-Peer System for a Virtual Organization

17.1 Introduction

17.1.1 The Tourism Sector in the Balearic Islands

17.1.2 Decision making in the Destination

17.1.3 Domains of Knowledge

17.2 Requirements Analysis

17.2.1 Organizational Context Analysis

17.2.2 Use Cases Description Searching for Information

17.3 XAROP platform description

17.3.1 Knowledge Providing functionalities

17.3.2 Knowledge Searching Functionalities

17.3.3 Managing Security Permissions

17.4 Conclusions

References

18 Bibster - A Semantics-Based Bibliographic Peer-to-Peer System

18.1 Introduction

18.2 Major Use Cases for Bibster

18.3 Design of Bibster

18.3.1 Ontologies in Bibster

18.3.2 Bibster Architecture and Modules

18.4 Semantic Extraction of Bibliographic Metadata

18.5 Semantic Querying

18.6 Expertise Based Peer Selection

18.7 Semantic Duplicate Detection

18.8 Results

18.9 Related Work

18.10 Conclusion

References

Author Index