Linked Data: Evolving the Web into a Global Data Space (Synthesis Lectures on the Semanic Web)

The World Wide Web has enabled the creation of a global information space comprising linked documents. As the Web becomes ever more enmeshed with our daily lives, there is a growing desire for direct access to raw data not currently available on the Web or bound up in hypertext documents. Linked Data provides a publishing paradigm in which not only documents, but also data, can be a first class citizen of the Web, thereby enabling the extension of the Web with a global data space based on open standards - the Web of Data. In this Synthesis lecture we provide readers with a detailed technical introduction to Linked Data. We begin by outlining the basic principles of Linked Data, including coverage of relevant aspects of Web architecture. The remainder of the text is based around two main themes - the publication and consumption of Linked Data. Drawing on a practical Linked Data scenario, we provide guidance and best practices on: architectural approaches to publishing Linked Data; choosing URIs and vocabularies to identify and describe resources; deciding what data to return in a description of a resource on the Web; methods and frameworks for automated linking of data sets; and testing and debugging approaches for Linked Data deployments. We give an overview of existing Linked Data applications and then examine the architectures that are used to consume Linked Data from the Web, alongside existing tools and frameworks that enable these. Readers can expect to gain a rich technical understanding of Linked Data fundamentals, as the basis for application development, research or further study. Table of Contents: List of Figures / Introduction / Principles of Linked Data / The Web of Data / Linked Data Design Considerations / Recipes for Publishing Linked Data / Consuming Linked Data / Summary and Outlook The World Wide Web Has Enabled The Creation Of A Global Information Space Comprising Linked Documents. As The Web Becomes Ever More Enmeshed With Our Daily Lives, There Is A Growing Desire For Direct Access To Raw Data Not Currently Available On The Web Or Bound Up In Hypertext Documents. Linked Data Provides A Publishing Paradigm In Which Not Only Documents, But Also Data, Can Be A First Class Citizen Of The Web, Thereby Enabling The Extension Of The Web With A Global Data Space Based On Open Standards - The Web Of Data. In This Synthesis Lecture We Provide Readers With A Detailed Technical Introduction To Linked Data. We Begin By Outlining The Basic Principles Of Linked Data, Including Coverage Of Relevant Aspects Of Web Architecture. The Remainder Of The Text Is Based Around Two Main Themes - The Publication And Consumption Of Linked Data. Drawing On A Practical Linked Data Scenario, We Provide Guidance And Best Practices On: Architectural Approaches To Publishing Linked Data; Choosing Uris And Vocabularies To Identify And Describe Resources; Deciding What Data To Return In A Description Of A Resource On The Web; Methods And Frameworks For Automated Linking Of Data Sets; And Testing And Debugging Approaches For Linked Data Deployments. We Give An Overview Of Existing Linked Data Applications And Then Examine The Architectures That Are Used To Consume Linked Data From The Web, Alongside Existing Tools And Frameworks That Enable These. Readers Can Expect To Gain A Rich Technical Understanding Of Linked Data Fundamentals, As The Basis For Application Development, Research Or Further Study. 1. Introduction -- The Data Deluge -- The Rationale For Linked Data -- Structure Enables Sophisticated Processing -- Hyperlinks Connect Distributed Data -- From Data Islands To A Global Data Space -- Introducing Big Lynx Productions. 2. Principles Of Linked Data -- The Principles In A Nutshell -- Naming Things With Uris -- Making Uris Defererenceable -- 303 Uris -- Hash Uris -- Hash Versus 303 -- Providing Useful Rdf Information -- The Rdf Data Model -- Rdf Serialization Formats -- Including Links To Other Things -- Relationship Links -- Identity Links -- Vocabulary Links -- Conclusions. 3. The Web Of Data -- Bootstrapping The Web Of Data -- Topology Of The Web Of Data -- Cross-domain Data -- Geographic Data -- Media Data -- Government Data -- Libraries And Education -- Life Sciences Data -- Retail And Commerce -- User Generated Content And Social Media -- Conclusions. 4. Linked Data Design Considerations -- Using Uris As Names For Things -- Minting Http Uris -- Guidelines For Creating Cool Uris -- Example Uris -- Describing Things With Rdf -- Literal Triples And Outgoing Links -- Incoming Links -- Triples That Describe Related Resources -- Triples That Describe The Description -- Publishing Data About Data -- Describing A Data Set -- Provenance Metadata -- Licenses, Waivers And Norms For Data -- Choosing And Using Vocabularies To Describe Data -- Skos, Rdfs And Owl -- Rdfs Basics -- A Little Owl -- Reusing Existing Terms -- Selecting Vocabularies -- Defining Terms -- Making Links With Rdf -- Making Links Within A Data Set -- Making Links With External Data Sources -- Setting Rdf Links Manually -- Auto-generating Rdf Links. 5. Recipes For Publishing Linked Data -- Linked Data Publishing Patterns -- Patterns In A Nutshell -- Additional Considerations -- The Recipes -- Serving Linked Data As Static Rdf/xml Files -- Serving Linked Data As Rdf Embedded In Html Files -- Serving Rdf And Html With Custom Server-side Scripts -- Serving Linked Data From Relational Databases -- Serving Linked Data From Rdf Triple Stores -- Serving Linked Data By Wrapping Existing Application Or Web Apis -- Additional Approaches To Publishing Linked Data -- Testing And Debugging Linked Data -- Linked Data Publishing Checklist. 6. Consuming Linked Data -- Deployed Linked Data Applications -- Generic Applications -- Domain-specific Applications -- Developing A Linked Data Mashup -- Software Requirements -- Accessing Linked Data Uris -- Representing Data Locally Using Named Graphs -- Querying Local Data With Sparql -- Architecture Of Linked Data Applications -- Accessing The Web Of Data -- Vocabulary Mapping -- Identity Resolution -- Provenance Tracking -- Data Quality Assessment -- Caching Web Data Locally -- Using Web Data In The Application Context -- Effort Distribution Between Publishers, Consumers And Third Parties. 7. Summary And Outlook -- Bibliography -- Authors' Biographies. Tom Heath, Christian Bizer. Includes Bibliographical References (p. 111-120). List of Figures......Page 12 Preface......Page 14 The Data Deluge......Page 16 Structure Enables Sophisticated Processing......Page 17 Hyperlinks Connect Distributed Data......Page 18 From Data Islands to a Global Data Space......Page 19 Introducing Big Lynx Productions......Page 20 The Principles in a Nutshell......Page 22 Naming Things with URIs......Page 24 Making URIs Defererenceable......Page 25 303 URIs......Page 26 Hash URIs......Page 28 Hash versus 303......Page 29 The RDF Data Model......Page 30 RDF Serialization Formats......Page 33 Including Links to other Things......Page 35 Relationship Links......Page 36 Identity Links......Page 37 Vocabulary Links......Page 39 Conclusions......Page 40 The Web of Data......Page 44 Topology of the Web of Data......Page 45 Cross-Domain Data......Page 48 Media Data......Page 49 Government Data......Page 50 Libraries and Education......Page 51 Life Sciences Data......Page 52 User Generated Content and Social Media......Page 53 Conclusions......Page 54 Minting HTTP URIs......Page 56 Guidelines for Creating Cool URIs......Page 57 Example URIs......Page 58 Describing Things with RDF......Page 59 Literal Triples and Outgoing Links......Page 60 Triples that Describe Related Resources......Page 61 Triples that Describe the Description......Page 62 Describing a Data Set......Page 63 Licenses, Waivers and Norms for Data......Page 67 SKOS, RDFS and OWL......Page 71 RDFS Basics......Page 72 A Little OWL......Page 75 Reusing Existing Terms......Page 76 Selecting Vocabularies......Page 77 Defining Terms......Page 78 Making Links with External Data Sources......Page 79 Auto-generating RDF Links......Page 81 Patterns in a Nutshell......Page 84 Additional Considerations......Page 86 Serving Linked Data as Static RDF/XML Files......Page 87 Serving Linked Data as RDF Embedded in HTML Files......Page 89 Serving Linked Data from Relational Databases......Page 92 Serving Linked Data by Wrapping Existing Application or Web APIs......Page 94 Testing and Debugging Linked Data......Page 95 Linked Data Publishing Checklist......Page 97 Deployed Linked Data Applications......Page 100 Generic Applications......Page 101 Domain-specific Applications......Page 105 Developing a Linked Data Mashup......Page 108 Accessing Linked Data URIs......Page 109 Representing Data Locally using Named Graphs......Page 110 Querying Local Data with SPARQL......Page 111 Architecture of Linked Data Applications......Page 112 Accessing the Web of Data......Page 115 Vocabulary Mapping......Page 116 Identity Resolution......Page 117 Data Quality Assessment......Page 118 Effort Distribution between Publishers, Consumers and Third Parties......Page 120 Summary and Outlook......Page 124 Bibliography......Page 126 Authors' Biographies......Page 136