reword ................................................................... xi
Preface .................................................................... xiii
Part I. Semantic Data
1.Why Semantics? ........................................................ 3
Data Integration Across the Web
4
Traditional Data-Modeling Methods
5
Tabular Data
6
Relational Data
7
Evolving and Refactoring Schemas
9
Very Complicated Schemas
11
Getting It Right the First Time
12
Semantic Relationships
14
Metadata Is Data
16
Building for the Unexpected
16
“Perpetual Beta”
17
2.Expressing Meaning .................................................... 19
An Example: Movie Data
21
Building a Simple Triplestore
23
Indexes
23
The add and remove Methods
24
Querying
25
Merging Graphs
26
Adding and Querying Movie Data
28
Other Examples
29
Places
29
Celebrities
31
Business
33
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3.Using Semantic Data ................................................... 37
A Simple Query Language
37
Variable Binding
38
Implementing a Query Language
40
Feed-Forward Inference
43
Inferring New Triples
43
Geocoding
45
Chains of Rules
47
A Word About “Artificial Intelligence”
50
Searching for Connections
50
Six Degrees of Kevin Bacon
51
Shared Keys and Overlapping Graphs
53
Example: Joining the Business and Places Graphs
53
Querying the Joined Graph
54
Basic Graph Visualization
55
Graphviz
55
Displaying Sets of Triples
56
Displaying Query Results
57
Semantic Data Is Flexible
59
Part II. Standards and Sources
4.Just Enough RDF ....................................................... 63
What Is RDF?
63
The RDF Data Model
64
URIs As Strong Keys
64
Resources
65
Blank Nodes
66
Literal Values
68
RDF Serialization Formats
68
A Graph of Friends
69
N-Triples
70
N3
72
RDF/XML
73
RDFa
76
Introducing RDFLib
80
Persistence with RDFLib
83
SPARQL
84
SELECT Query Form
86
OPTIONAL and FILTER Constraints
87
Multiple Graph Patterns
89
CONSTRUCT Query Form
91
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ASK and DESCRIBE Query Forms
91
SPARQL Queries in RDFLib
92
Useful Query Modifiers
94
5.Sources of Semantic Data ............................................... 97
Friend of a Friend (FOAF)
97
Graph Analysis of a Social Network
101
Linked Data
105
The Cloud of Data
106
Are You Your FOAF file?
107
Consuming Linked Data
110
Freebase
116
An Identity Database
117
RDF Interface
118
Freebase Schema
119
MQL Interface
121
Using the metaweb.py Library
123
Interacting with Humans
125
6.What Do You Mean, “Ontology”? ........................................ 127
What Is It Good For?
127
A Contract for Meaning
128
Models Are Data
128
An Introduction to Data Modeling
129
Classes and Properties
129
Modeling Films
132
Reifying Relationships
134
Just Enough OWL
135
Using Protégé
140
Creating a New Ontology
140
Editing an Ontology
141
Just a Bit More OWL
145
Functional and Inverse Functional Properties
146
Inverse Properties
146
Disjoint Classes
146
Keepin’ It Real
148
Some Other Ontologies
148
Describing FOAF
148
A Beer Ontology
149
This Is Not My Beautiful Relational Schema!
152
7.Publishing Semantic Data .............................................. 155
Embedding Semantics
155
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Microformats
156
RDFa
158
Yahoo! SearchMonkey
160
Google’s Rich Snippets
161
Dealing with Legacy Data
162
Internet Video Archive
162
Tables and Spreadsheets
167
Legacy Relational Data
169
RDFLib to Linked Data
172
Part III. Putting It into Practice
8.Overview of Toolkits ................................................... 183
Sesame
183
Using the Sesame Java API
184
RDFS Inferencing in Sesame
193
A Servlet Container for the Sesame Server
196
Installing the Sesame Web Application
196
The Workbench
197
Adding Data
199
SPARQL Queries
200
REST API
202
Other RDF Stores
203
Jena (Open Source)
204
Redland (Open Source)
204
Mulgara (Open Source)
204
OpenLink Virtuoso (Commercial and Open Source)
204
Franz AllegroGraph (Commercial)
205
Oracle (Commercial)
205
SIMILE/Exhibit
205
A Simple Exhibit Page
206
Searching, Filtering, and Prettier Views
209
Linking Up to Sesame
211
Timelines
212
9.Introspecting Objects from Data ......................................... 215
RDFObject Examples
215
RDFObject Framework
217
How RDFObject Works
225
10.Tying It All Together ................................................... 227
A Job Listing Application
227
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Application Requirements
228
Job Listing Data
228
Converting to RDF
228
Loading the Data into Sesame
231
Serving the Website
232
CherryPy
232
Mako Page Templates
233
A Generic Viewer
234
Getting Data from Sesame
236
The Generic Template
236
Getting Company Data
237
Crunchbase
238
Yahoo! Finance
241
Reconciling Freebase Connections
243
Specialized Views
244
Publishing for Others
248
RDFa
248
RDF/XML
250
Expanding the Data
251
Locations
251
Geography, Economy, Demography
252
Sophisticated Queries
253
Visualizing the Job Data
255
Further Expansion
258
Part IV. Epilogue
11.The Giant Global Graph ................................................ 261
Vision, Hype, and Reality
262
Participating in the Global Graph Community
264
Releasing Data into the Commons
265
License Considerations
266
The Data Cycle
267
Bracing for Continuous Change
268
Index ..................................................................... 271
