THE SEMANTIC WEB CRAFTING INFRASTRUCTURE FOR AGENCY Bo Leuf Technology Analyst, Sweden THE SEMANTIC WEB THE SEMANTIC WEB CRAFTING INFRASTRUCTURE FOR AGENCY Bo Leuf Technology Analyst, Sweden Copyright#2006 JohnWiley&SonsLtd,TheAtrium,SouthernGate,Chichester, WestSussexPO198SQ,England Telephone (+44)1243779777 Email(forordersandcustomerserviceenquiries):[email protected] VisitourHomePageonwww.wiley.com AllRightsReserved.Nopartofthispublicationmaybereproduced,storedinaretrievalsystemortransmitted inanyformorbyanymeans,electronic,mechanical,photocopying,recording,scanningorotherwise, exceptunderthetermsoftheCopyright,DesignsandPatentsAct1988orunderthetermsofalicenceissued bytheCopyrightLicensingAgencyLtd,90TottenhamCourtRoad,LondonW1T4LP,UK,withoutthe permissioninwritingofthePublisher.RequeststothePublishershouldbeaddressedtothePermissions Department,JohnWiley&SonsLtd,TheAtrium,SouthernGate,Chichester,WestSussexPO198SQ, England,[email protected],orfaxedto(+44)1243770620. Thispublicationisdesignedtoprovideaccurateandauthoritativeinformationinregardtothesubjectmatter covered.ItissoldontheunderstandingthatthePublisherisnotengagedinrenderingprofessional services.Ifprofessionaladviceorotherexpertassistanceisrequired,theservicesofacompetent professionalshouldbesought. OtherWileyEditorialOffices JohnWiley&SonsInc.,111RiverStreet,Hoboken,NJ07030,USA Jossey-Bass,989MarketStreet,SanFrancisco,CA94103-1741,USA Wiley-VCHVerlagGmbH,Boschstr.12,D-69469Weinheim,Germany JohnWiley&SonsAustraliaLtd,42McDougallStreet,Milton,Queensland4064,Australia JohnWiley&Sons(Asia)PteLtd,2ClementiLoop#02-01,JinXingDistripark,Singapore129809 JohnWiley&SonsCanadaLtd,22WorcesterRoad,Etobicoke,Ontario,CanadaM9W1L1 Wileyalsopublishesitsbooksinavarietyofelectronicformats.Somecontentthatappearsin printmaynotbeavailableinelectronicbooks. LibraryofCongressCataloging-in-PublicationData Leuf,Bo,TechnologyAnalyst,Sweden. TheSemanticWeb:craftinginfrastructureforagency/BoLeuf. p.cm. Includesbibliographicalreferencesandindex. ISBN0-470-01522-5 1. SemanticWeb.I.Title. TK5105.88815.L482005 025.04–dc22 2005024855 BritishLibraryCataloguinginPublicationData AcataloguerecordforthisbookisavailablefromtheBritishLibrary ISBN-13978-0-470-01522-3(HB) ISBN-100-470-01522-5(HB) Typesetin10/12ptTimesRomanbyThomsonPress(India)Limited,NewDelhi PrintedandboundinGreatBritainbyAntonyRowe,Chippenham,Wilts Thisbookisprintedonacid-freepaperresponsiblymanufacturedfromsustainableforestry inwhichatleasttwotreesareplantedforeachoneusedforpaperproduction. I dedicate this book to the many visionaries, architects, and programmers, who all made the Internet an interesting place to ‘live’ and work in. And especially to Therese. Contents Foreword xiii Preface xv Part I Content Concepts 1 Enhancing the Web 3 Chapter 1 at a Glance 3 There and Back Again 4 Resource Identifiers 5 Extending Web Functionality 11 From Flat Hyperlink Model 17 To Richer Informational Structures 22 The Collaboration Aspect 23 Extending the Content Model 26 Mapping the Infosphere 27 Well-Defined Semantic Models 30 2 Defining the Semantic Web 31 Chapter 2 at a Glance 31 From Model to Reality 32 The Semantic Web Concept 33 Representational Models 43 The Road Map 46 Identity 46 Markup 49 Relationships 49 Reasoning 51 Agency on the Web 52 Semantic P2P 52 The Visual Tour 53 The Map 54 The Architectural Goals 55 The Implementation Levels 57