Ontology Driven Multi-Agent Systems: an Architecture for Sensor Web Applications
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ONTOLOGY DRIVEN MULTI-AGENT SYSTEMS: AN ARCHITECTURE FOR SENSOR WEB APPLICATIONS by DESHENDRAN MOODLEY Submitted in fulfillment of the academic requirements for the degree of Doctor of Philosophy in the School of Computer Science, Faculty of Science and Agriculture, University of KwaZulu-Natal, Durban, South Africa, December 2009 As the candidate’s supervisor I have approved this dissertation for submission. Signed: Name: Date: ABSTRACT Advances in sensor technology and space science have resulted in the availability of vast quantities of high quality earth observation data. This data can be used for monitoring the earth and to enhance our understanding of natural processes. Sensor Web researchers are working on constructing a worldwide computing infrastructure that enables dynamic sharing and analysis of complex heterogeneous earth ob- servation data sets. Key challenges that are currently being investigated include data integration; service discovery, reuse and composition; semantic interoperability; and system dynamism. Two emerging tech- nologies that have shown promise in dealing with these challenges are ontologies and software agents. This research investigates how these technologies can be integrated into an Ontology Driven Multi-Agent System (ODMAS) for the Sensor Web. The research proposes an ODMAS framework and an implemented middleware platform, i.e. the Sensor Web Agent Platform (SWAP). SWAP deals with ontology construction, ontology use, and agent based design, implementation and deployment. It provides a semantic infrastructure, an abstract architec- ture, an internal agent architecture and a Multi-Agent System (MAS) middleware platform. Distinguish- ing features include: the incorporation of Bayesian Networks to represent and reason about uncertain knowledge; ontologies to describe system entities such as agent services, interaction protocols and agent workflows; and a flexible adapter based MAS platform that facilitates agent development, execution and deployment. SWAP aims to guide and ease the design, development and deployment of dynamic alerting and monitoring applications. The efficacy of SWAP is demonstrated by two satellite image processing applications, viz. wildfire detection and monitoring informal settlement. This approach can provide sig- nificant benefits to a wide range of Sensor Web users. These include: developers for deploying agents and agent based applications; end users for accessing, managing and visualising information provided by real time monitoring applications, and scientists who can use the Sensor Web as a scientific computing platform to facilitate knowledge sharing and discovery. An Ontology Driven Multi-Agent Sensor Web has the potential to forever change the way in which geospatial data and knowledge is accessed and used. This research describes this far reaching vision, identifies key challenges and provides a first step towards the vision. ii PREFACE The research work described in this dissertation was carried out in the School of Computer Science, University of KwaZulu-Natal, Durban, from March 2001 to December 2009, under the supervision of Prof. Jules R. Tapamo and Prof. Johnson D.M. Kinyua These studies represent original work by the author and have not otherwise been submitted in any form for any degree or diploma to any tertiary institution. Where use has been made of the work of others it is duly acknowledged in the text. iii DECLARATION 1 - PLAGIARISM I, Deshendran Moodley, declare that: 1. The research reported in this thesis, except where otherwise indicated, is my original research. 2. This thesis has not been submitted for any degree or examination at any other university. 3. This thesis does not contain other persons’ data, pictures, graphs or other information, unless specifically acknowledged as being sourced from other persons. 4. This thesis does not contain other persons’ writing, unless specifically acknowledged as being sourced from other researchers. Where other written sources have been quoted, then: (a) Their words have been re-written but the general information attributed to them has been referenced (b) Where their exact words have been used, then their writing has been placed in italics and inside quotation marks, and referenced. 5. This thesis does not contain text, graphics or tables copied and pasted from the Internet, unless specifically acknowledged, and the source being detailed in the thesis and in the References sec- tions. Signed: iv DECLARATION 2 - PUBLICATIONS 1.M OODLEY, D., AND KINYUA, J. A multi-agent system for electronic job markets. In Proc. 6th International conference on Business Information Systems, Colorado Springs, USA, 4-6 June 2003, published by Dept. of Management Info. Systems, The Poznan University of Economics, Poznan (2003), pp. 42–48 2.M OODLEY, D. The future of the Internet: The semantic web, web services and a multi-agent system infrastructure for the Internet. In Proc. South African Computer Lecturers Association 2004, 4-6 July Durban, 2004 (2004) 3.M OODLEY, D., AND KINYUA, J. D. M. Towards a multi-agent infrastructure for distributed In- ternet applications. In 8th Annual Conference on WWW Applications, Bloemfontein, South Africa, 5-6 September (2006) 4.M OODLEY, D., TERHORST, A., SIMONIS, I., MCFERREN, G., AND VAN DEN BERGH, F. Using the sensor web to detect and monitor the spread of wild fires. In Second International Symposium on Geo-information for Disaster Management (Gi4DM) September 25-26, Pre-Conference Sympo- sium to ISPRS TC-IV and ISRS Symposium on Geospatial Databases for Sustainable Development September 27-30, at Goa, India (2006) 5.M OODLEY, D., AND SIMONIS, I. A new architecture for the sensor web: the SWAP-framework. In Semantic Sensor Networks Workshop, A workshop of the 5th International Semantic Web Con- ference ISWC 2006, November 5-9, Athens, Georgia, USA (2006) 6.T ERHORST, A., SIMONIS, I., AND MOODLEY, D. A service-oriented multi-agent systems archi- tecture for the sensor web. In SAEON Summit, Centurion, South Africa (2006) 7.M OODLEY, D., VAHED, A., SIMONIS, I., MCFERREN, G., AND ZYL, T. V. Enabling a new era of earth observation research: scientific workflows for the sensor web. Ecological Circuits 1 (2008), 20–23 8.T ERHORST, A., MOODLEY, D., SIMONIS, I., FROST, P., MCFERREN, G., ROOS, S., AND VAN DEN BERGH, F. Geosensor Networks, Lecture Notes in Computer Science, Volume 4540/2008. Springer-Verlag, 2008, ch. Using the Sensor Web to Detect and Monitor the Spread of Vegetation Fires in Southern Africa, pp. 239–251 Signed: v ACKNOWLEDGEMENTS Many people have supported me through this endeavour. I am deeply grateful to my wife for her patience, understanding, support and for allowing the PhD to permeate our lives over the past few years. I wish to express sincere gratitude to my supervisor Jules Tapamo for his support and guidance, and to my co-supervisor Johnson Kinyua for his support and guidance through the early stages. I would like to thank my parents, my family and my dear friends who have supported me. A special thank you to Anban Pillay for being a dear friend, and for willing to sacrifice many hours for proof reading. I wish to also acknowledge and thank: Chetna Parbhoo for designing and implementing the second case study application as part of her Masters research; Pravi Moodley who assisted with the proof read- ing; members of the ICT4EO and KSG groups at the Meraka Institute, CSIR, Pretoria, specifically Ingo Simonis and Tommie Meyer. I also acknowledge the financial support provided by the National Research Foundation and the German Academic Exchange Service (DAAD) . vi TABLE OF CONTENTS Preface ................................................ iii Declarations ............................................. iv Acknowledgements ......................................... vi Table of Contents .......................................... vii List of Figures ............................................ xii List of Tables ............................................. xviii List of Abbreviations ........................................ xix Chapter 1 Introduction .................................... 1 1.1 Background . .1 1.2 Problem statement . .3 1.3 Expected impact . .3 1.4 The SWAP framework . .4 1.4.1 Semantic infrastructure . .4 1.4.2 MASII: An Internet Wide Multi Agent System middleware . .5 1.4.3 Framework for designing and developing Sensor Web agents and applications . .5 1.4.4 Application case studies . .6 1.5 Organisation of the thesis . .6 Chapter 2 Literature review .................................. 8 2.1 The Sensor Web . .8 2.1.1 Our vision of the Sensor Web . 10 2.1.2 OGC Sensor Web Enablement . 12 2.1.3 GeoSwift . 13 vii 2.2 Software agents and multiagent systems for Internet Computing . 14 2.2.1 Agent operation . 15 2.2.2 MAS infrastructure models and platforms . 18 2.2.3 Challenges for building an Internet Wide MAS (IWMAS) . 20 2.3 Ontologies and the Semantic Web . 22 2.3.1 Ontology Representation languages . 25 2.3.2 Ontology development and management . 29 2.3.3 Ontology based systems . 32 2.3.4 Agents and the Semantic Web . 33 2.4 Agents and ontologies on the Sensor Web . 34 2.4.1 Agent based approaches . 34 2.4.2 Ontology based Sensor Web approaches . 36 2.5 Summary . 39 Chapter 3 Design of an Internet Wide Multi-Agent System Infrastructure ........ 40 3.1 Requirements for a single global multi-agent infrastructure . 40 3.2 The Multi-Agent Infrastructure for the Internet . 42 3.2.1 An abstract architecture for a IWMAS . 42 3.3 MASII design and operation . 45 3.3.1 Registry Agent (RA) . 46 3.3.2 Adapter agent (AA) . 46 3.3.3 Platform implementation . 47 3.3.4 Application development . 48 3.4 Application deployment . 49 3.5 Discussion . 49 Chapter 4 Design of the Sensor Web Agent Platform .................... 51 4.1 Our vision of the Sensor Web . 51 4.2 The SWAP Abstract Architecture . 52 4.2.1 Sensor Layer . 52 4.2.2 Knowledge Layer . 54 viii 4.2.3 Application Layer . 54 4.2.4 Incorporating OGC services . 55 4.3 Overview of the SWAP Ontological Infrastructure . 55 4.3.1 Rationale behind the SWAP ontology . 55 4.3.2 Swap rules . 57 4.4 The SWAP conceptual ontologies . 59 4.4.1 Thematic representation and reasoning .