Foreword xxiii
Introduction xxv
Part One Introducing Semantic Web Programming 1
Chapter 1 Preparing to Program a Semantic Web of Data 3
Defining the Semantic Web 4
Identifying the Major Programming Components 10
Determining Impacts on Programming 13
Establishing a Web Data-Centric Perspective 13
Expressing Semantic Data 14
Sharing Data 16
Making Data Dynamic and Flexible 18
Avoiding the Roadblocks, Myths, and Hype 19
Semantic Web Roadblocks 19
Semantic Web Myths 21
Semantic Web Hype 22
Understanding Semantic Web Origins 23
Exploring Semantic Web Examples 26
Semantic Wikis (semantic-mediawiki.org) 26
Twine (www.twine.com) 27
The FOAF Project (www.foaf-project.org) 28
RDFa and Microformats 30
Semantic Query Endpoint (dbpedia.org/sparql) 32
Semantic Search (www.trueknowledge.com) 32
Summary and Onward 34
Notes 34
Chapter 2 Hello Semantic Web World 35
Setting Up Your Semantic Web Development Environment 36
Programming the Hello Semantic Web World Application 38
Summary 58
Part Two Foundations of Semantic Web Programming 61
Chapter 3 Modeling Information 63
Modeling Information in Software 64
Sharing Information: Syntax and Semantics 65
Serialized Objects 66
Relational Databases 66
Extensible Markup Language (XML) 66
Metadata and Data in Information Sharing 67
The Semantic Web Information Model: The Resource Description Framework (RDF) 68
Nodes: Resources and Literals 69
Edges: Predicates 71
Exchanging Information with RDF 72
Statements as Points 73
RDF Serializations 74
RDF/XML 74
Terse RDF Triple Language (Turtle) 78
N-Triples 81
Quick Hack 82
More RDF 84
Blank Nodes 84
Reification 88
RDF Organizational Constructs 88
Summary 91
Chapter 4 Incorporating Semantics 93
Semantics on the Web 94
Motivating Factors 94
Understanding the World WideWeb 95
Knowledge Domain Integration 97
Expressing Semantics in RDF 98
Vocabularies, Taxonomies, and Ontologies 99
A Vocabulary Language for RDF 100
An Ontology Language for the Web 101
Introduction to Ontologies 102
Distributed Knowledge 102
Open World Assumption 103
No Unique Names Assumption 104
Overview of Ontology Elements 104
Ontology Header 105
Classes and Individuals 105
Properties 106
Annotations 106
Data types 106
Elements of an Ontology 107
OWL 2 Typing 107
Ontology Header 108
Annotations 109
Basic Classification 110
Classes and Individuals 110
rdfs:SubClassOf 111
Instance versus Subclass 112
owl:Thing and owl:Nothing 113
Defining and Using Properties 113
Property Domain and Range 114
Describing Properties 115
rdfs:subPropertyOf 115
Top and Bottom Properties 116
Inverse Properties 116
Disjoint Properties 117
Property Chains 118
Symmetric, Reflexive, and Transitive Properties 119
Functional and Inverse Functional Properties 120
Keys 121
Datatypes 122
Data type Restrictions 122
Defining Datatypes in Terms of Other Datatypes 124
Negative Property Assertions 126
Property Restrictions 127
Value Restrictions 127
Cardinality Restrictions 130
Qualified Cardinality Restrictions 132
Advanced Class Description 134
Enumerating Class Membership 134
Set Operators 134
Disjoint Classes 136
Equivalence in OWL 137
Equivalence among Individuals 138
Equivalence among Classes and Properties 139
Summary 139
Chapter 5 Modeling Knowledge in the Real World 141
Exploring the Components of the Semantic Web 141
Semantic Web Frameworks 143
Storing and Retrieving RDF 144
RDF Store Implementations 144
Retrieving Information in a Knowledgebase 146
Realizing the Semantics of OWL 147
Understanding Forward Chaining Inference 148
Understanding Backward Chaining Inference 152
Choosing the Right Inference Method 153
Common Frameworks and Components 153
RDF Store Implementations 154
Retrieval Components 156
Reasoning Engines 156
Knowledgebase Performance 157
Exploring the Profiles of OWL 158
OWL Full and OWL DL 159
The Profiles of OWL 160
OWL EL 160
OWL QL 161
OWL RL 162
Demonstrating OWL Inference 163
The Ontology 163
The Example Application 165
The Results 169
Performing No Inference 169
Performing RDFS Inference 170
Performing OWL Inference 171
Working with Ontologies 172
Decoupling the Knowledge Model from the Application 173
Sharing across Domain and Application Boundaries 174
What Is a Foundational Ontology? 175
Common Foundational Ontologies 177
BFO 177
Cyc and OpenCyc 178
DOLCE 179
SUMO 179
Dublin Core Metadata Initiative 179
FOAF 180
GeoRSS and OWL-Time 180
Finding Ontologies to Reuse or Extend 181
Choosing the Right Foundational Ontologies 183
Summary 184
Chapter 6 Discovering Information 185
Navigating the Semantic Web 186
Searching the Semantic Web 190
Querying the Semantic Web 192
Quickstart with SPARQL 192
Four Foundational Query Forms 196
SELECT Essentials 197
RDF Datasets, FROM and FROM NAMED 202
Query Modifiers 208
DISTINCT 209
REDUCED 210
ORDER BY 210
Data Streaming with OFFSET and LIMIT 211
Flexible Querying with FILTER and OPTIONAL 213
FILTER 213
OPTIONAL 215
UNION 219
CONSTRUCT Essentials 222
DESCRIBE Essentials 224
ASK Essentials 225
SPARQL Entailment 226
Unsupported Functionality 228
Data Modification 228
Subqueries 228
Aggregation 228
Summary 229
Chapter 7 Adding Rules 231
What Are Rules? 232
Reasons for Rules 232
No Support for Property Composition 232
Use of Built-ins 232
Ontological Mediation 233
Limiting Assumptions 233
Rule Languages 233
SWRL Essentials 234
The Abstract Syntax 235
The XML Concrete Syntax 237
var 238
imp 239
_rlab 239
_body 239
_head 240
classAtom 240
datarangeAtom 241
individualPropertyAtom 241
datavaluedPropertyAtom 242
sameIndividualAtom 242
differentIndividualsAtom 243
builtinAtom 243
The RDF Concrete Syntax 243
Built-ins 244
Examples 244
DL-Safe Rules 245
Ontological Mediation 252
Mapping Friends without Upsetting Any of Them 253
The Power of Rules 256
Jena Rules 257
Rule Interchange Format 259
Delving into the Details 260
The Future of RIF 260
Summary 261
Part Three Building Semantic Web Applications 263
Chapter 8 Applying a Programming Framework 265
Framing the Semantic Web 266
The Jena SemanticWeb Framework 269
Defining Jena Programming Concepts 269
Programming with Jena 273
Establishing the Jena Development Environment 276
Establishing the Knowledgebase: Setting Up the Model 276
Populating the Model with Semantic Web Data 279
Combining Semantic Web Data 282
Interrogating Semantic Web Data 283
Reasoning across Semantic Web Data 285
Exporting Semantic Web Data 290
Deallocating Semantic Web Data Resources 290
Managing Semantic Web Data 291
Getting Information Regarding Your Semantic Web Data 291
Generating Events Based on Semantic Web Data 292
Dealing with Concurrency and Your Semantic Web Data 293
Customizing the Jena Framework 295
Serializing Semantic Web Data 297
Common App Overview: FriendTracker 298
Summary 299
Chapter 9 Combining Information 301
Combining Information 303
Representing Information 303
Translating between Representations 304
Addressing the Challenges of Translation 305
Maintaining Fidelity 305
Tracking Provenance Information 305
Reversing the Process 306
Handling Varying Data 306
Managing Data Volume 306
Introducing the FriendTracker Data Sources 307
Facebook XML Web Service 307
Jabber Java Client 308
Upcoming.org XML Web Service 308
WordPress Relational Database 308
Exposing XML-Based Web Services as RDF 309
Introducing the Weather.gov XML Feed 310
Exposing XML Using XSL Transformations 311
Traversing XML Documents with XPath 313
Applying XSLT to a Simple Example 315
Processing XML and XSLT Programmatically 319
Applying XSLT to the Facebook Data Source 322
Weighing the Benefits and the Costs of XSLT 326
Exposing XML Using XML Bindings and Velocity 328
Generating Java Bindings for XML Data 329
Unmarshalling XML Data into Java 331
Introducing the Velocity Template Engine 333
Generating RDF with Velocity 336
Weighing the Benefits and the Costs 336
Exposing Relational Databases as RDF 337
Exposing a WordPress Blog Using D2RQ 338
Creating D2RQ Mappings for the WordPress Database 339
Wrapping the D2RQ Instance in a Jena Model 341
Querying the D2RQ Exposed WordPress Database 342
Weighing the Benefits and the Costs of D2RQ 345
Exposing Other Sources of Data 346
Exposing Jabber with a Custom Streaming RDF Writer 346
Exposing Java Objects Using Reflection 352
Applying the RDF Generator to the Weather.gov XML Feed 356
Applying the RDF Generator to the Upcoming.org XML Feed 358
Summary 359
Chapter 10 Aligning Information 361
Data Source, Domain, and Application Ontologies 361
Aligning Ontologies 362
Ontology Constructs 363
Translation via Rules 365
Explicit Translation 365
Ad Hoc Approaches to Translation 366
FriendTracker 366
Aligning Ontologies with OWL and SWRL 372
Aligning Ontologies with XSLT 376
Aligning Ontologies with Code 381
Aligning Simple Ontologies with RDFS 382
Record Linkage 385
Summary 388
Chapter 11 Sharing Information 389
Microformats 390
eRDF 392
RDFa 395
Supported Attributes 396
xmlns 396
rel 396
rev 398
content 398
href 399
src 399
about 399
property 399
resource 400
datatype 401
typeof 401
Blank Nodes 402
Language Support 403
Tools and Frameworks 404
RDF Transformational Tools 404
SPARQL Endpoints 404
Joseki Installation and Operation 405
xOperator 408
Installation and Operation 409
Example Query 410
FriendTracker in RDFa 411
Summary 417
Part Four Expanding Semantic Web Programming 419
Chapter 12 Developing and Using Semantic Services 421
Background 422
Discovery 424
Invocation 424
Negotiation 425
Error Handling 425
Monitoring 425
Composition 425
Implementing Semantic Services 426
Semantic Markup for Web Services 427
ServiceProfile 428
ServiceModel 428
ServiceGrounding 428
Web Service Modeling Ontology 429
Semantic Annotations for WSDL 432
SAWSDL Example 433
SAWSDL Tools 434
Summary 435
Chapter 13 Managing Space and Time 437
Space and Time in Software 437
Spatial Information 438
Temporal Information 440
Representing Spatiotemporal Data on the SemanticWeb 441
Spatial and Temporal Software with Jena 450
Working with Spatial Data 452
Example: Spatial Queries 453
Framing the Problem 453
Approach and Rationale 454
Components 454
Example: Transaction Time-Bounded Queries 461
Framing the Problem 461
Approach and Rationale 462
Components 462
Summary 465
Notes 465
Chapter 14 Semantic Web Patterns and Best Practices 467
Aggregating Disparate Data Sources 468
Exposing Data Sources as RDF 469
Bringing Data into the Domain Knowledge Model 470
Storing Information in the Knowledgebase 472
Initiating the Flow of Data 472
Annotating Unstructured Data 472
Annotation Management 474
Ontology Management 475
Unstructured Data Sources and the Client Application 476
Coordinating Semantic Services 478
Applying SemanticWeb Best Practices 480
Creating URIs 480
Making URIs Unique 480
Making URIs Consistent 481
Making URIs Resolvable 483
Specifying Units of Measurement 483
Unit-Specific Properties and Datatypes 484
Statement Reification 485
Value Containers 485
Representing N-ary Relationships 486
Managing Bad Data 487
Summary 487
Chapter 15 Moving Forward 489
Advancing Ontologies 491
Ontology Repositories and Registries 491
Linked Data 492
Versioning 493
Ontology Metrics 495
Advancing Integration 497
Semantic Pipes 497
Distributed Queries 498
Alignment 500
Advancing Reasoning 506
Rule Interchange Format (RIF) 506
Probabilistic Reasoning 507
Trust: Proof Markup Language 510
LarKC: The Large Knowledge Collider 512
Advancing Visualization 513
Summary 516
Appendix A RDF 519
Appendix B The OWL Web Ontology Language 525
Appendix C SWRL 533
Appendix D SPARQL 555
Appendix E Jena Reference Guide 567
Appendix F Installation Reference Guide 577
Index 585
