National tibrary Bibliothèque nationale l*l of Canada du Canada Acquisitions and Acquisitions et Bibliographic Services services bibliographiques 395 Wellinglon Street 395,rue Wellington Ottawa ON KIAOW Onawa ON K1A ON4 Canada Canada Vour Ne Votre rdlemnco Our liki Noue reldienw The author has granted a non- L'auteur a accordé une licence non exclusive licence dowing the exclusive permettant à la National Library of Canada to Bibliothèque nationale du Canada de reproduce, loan, distribute or seil reproduire, prêter, distribuer ou copies of this thesis in microform, vendre des copies de cette thèse sous paper or elec~onicformats. la forme de microfiche/film, de reproduction sur papier ou sur format électronique. The author retains ownership of the L'auteur conserve la propriété du copyright in this thesis. Neither the droit d'auteur qui protège cette thèse. thesis nor substantial extracts fiom it Ni la thèse ni des extraits substantiels may be printed or othenvise de celle-ci ne doivent être imprimés reproduced without the author's ou autrement reproduits sans son permission. autorisation. Abstract We are overwhelmed by the growing availabiiity of information sources in this information age. It becomes harder for peopIe to extract relevant and useful infomation fiom information sources such as the Web. It also becornes harder for people to distribute their information to the relevant people who will find it usehl through the Internet. Information retrieval and information filtering are comrnonly used techniques to address the information overload problem. This thesis deals with a community-based rnulti-agent information retrieval and provision system. It focusses on the development of a keyphrase-based information sharing system for a commwiity of mobiie agents. Ln this thesis we first review the concept of software agents and their applications. Subsequently, we describe the information sharing activities in our daify life and the requirements that our proposed system should possess. The agents are classified into three categories and their data structures are given. The proposed infomation sharing systern is implemented using the Java programming language and its muitithreading technique. Finaliy, we incorporate the cosine measure method into the Agent-based Cornrnunity-Onented Routing Network system (ACORN). We test and evaluate our system by using actual data, which venfies that this system has fuIfilled the design requirements. We incorporate the cosine measure method into ACON and compare the test resuiis of ACORN before and after the incorporation of the cosine measure method. The results indicate that the ACORN . F .. , . ...--------A L-.A- :-1----4;-~ -$+ha C;-;~O~-I marnc~~teme+hnd lIlLO~TIlaUunsriaruiii; iS iiiipiuvcu uy uii; iiikurpuioiiuii U& uir JU~~~~~.~.ri--rri. Acknowledgments I would like to express my special thanks to my supervisors Dr. V.C. Bhavsar, Dr. A. Ghorbani, and Dr. S. Marsh for their guidance and assistance throughout this thesis research and writing. 1 would aiso like to thank my parents, and my daughter Angela Mengyang Yu for their constant encouragement, patience, understanding, and support. Table of Contents .. Abstract ......................................................................................................................................................11 .. Acknowledgrnent................................................................................................................................... 111 ... List of Tables ........................................................................................................................................VIII List of Figures .......................................................................................................................................ix Chapter 1 Introduction 1 . 1.1 Background and Motivation ,...............,+............... ........................ 1 . 1.2 Thesis Objectives ...................... ....... .................... ............................................... 4 1.3 Thesis Outline..................................................................................................... 5 Chapter 2 Software Agents 7 2.1 Definition............................................................................................................. 7 2.2 Classification ......................................... ...,...., ....... ...... ............................... .... ....S , . 2.3 Applications ............................................................................................... 10 2.3.1 Electronic Mail ..... ..............-.............. ...................................................... 1 O 2.3.2 Usenet Netnews ................................ ................................. ................. 1 1 2.3.3 Web Browsing ................................................. ..................................... 1 I 2.3.4 Electronic Commerce ............................................................................ 12 2.3.5 Entertainment ..... .*.. ... ...... .. .... ... .. .... ... ...... ... ....... ... ..... .... ... ..... .... ....... .. .. .. 1 3 2.3.6 Other Activities ...................................................................................14 2.4 Information RetrievaI and Information Filtering ...........,......... .......................15 2.4.1 Information Retrieval ....................,,..........~........,,,,...............................,, 15 . 2.4.2 Information Filtering ...............................................................................17 2.5 Community-based Agent Systems .....................................................................19 2.5.1 ACORN ..................................................................................................19 2 5 1 . 1 Architecture ...............................................................................20 . 2.5.1 2 Migration and Interactions .........................................................23 2.5.2 Yenta .......................................................................................................24 2.5.3 Kasbah ................................................................................................... 25 2.6 Concluding Remarks .......................................................................................... 27 Chapter 3 Keyphrase-bascd Information Sharing 2 8 3.1 Introduction ........................................................................................................28 3.2 Scenarios ............................................................................................................29 3.3 Concept of the Keyphrase-based Information Sharinç....................................... 32 3.4 System Architecture ......................................................................................... 32 3.1.1 Agent Categories .....................................................................................32 -! 9 3.4.2 The Café........................... .. ................................................................. JJ - . 3.3 Privacy .............. .... ....................................................................................36 3.6 Concluding Remarks .........................................................................................36 Chapter 4 Agents and the Café 38 4.1 Overview....................................................................................................................... 38 4.2 Agent Representation.................................................................................................... 39 4.2.1 Agent Data Structure.......................................................................................... 39 4.2.2 User Profile........................................................................................................ 44 4.2.3 Metadata ......................................................... :................................................... 47 4.3 The Cafe........................................................................................................................ 48 . 4.3.1 Similarity Measures ........................................................................................... 49 4.3.2 Information Sharing........................................................................................... 51 4.3 Surnmary ....................................................................................................................... 58 Chapter 5 ImpIementation. Test and Evaluation 60 5.1 Introduction ...................................................................................................................60 5.2 Implementation of Agents ............................................................................................. 60 5.2.1 Agent Class ........................................................................................................60 5.2.2 AgentCore Class................................................................................................ 62 5.2.3 KeyPhraseVector Class .................................................................................. 63 5.7.4 DublinCore Class.............................................................................................. 67 5.3 The Café 67 5.3.1 LetAgentin Thread ............................................................................................69 5.3.2 IntoSharing Thread ........................................................................................ 69 5.3.3 TimeChecker