The Semantic Web & Meta Data
An overview of the semantic data formats
and standards in use during 2009.
by Charl van Niekerk
www.charlvn.com
Copyright 2009. Some rights reserved.
This presentation slide show is released under the Creative Commons
Attribution-Share Alike 2.5 South Africa License.
The Semantic Web
Semantics = Meaning
Machine understandability of data
Conceptualised by Tim-Berners Lee
Various initiatives by standards bodies
http://en.wikipedia.org/wiki/Semantic_Web
http://semanticweb.org/
The Semantic Web & Meta Data
2009
The W3C Semantic Web
RDF (Resource Description Framework)
OWL (Web Ontology Language)
SPARQL (SPARQL Protocol and RDF Query Language)
RDFa (Resource Description Framework attributes)
GRDDL (Gleaning Resource Descriptions from Dialects of
Languages)
http://www.w3.org/2001/sw/
The Semantic Web & Meta Data
2009
Resource Description Framework (RDF)
Triples
Subject (Who? What?)
Predicate (What's the relationship?)
Object (What do we know?)
Serialisation
XML
Notation 3
Turtle
N-Triples
Triplestore
http://esw.w3.org/topic/LargeTripleStores
http://www.w3.org/RDF/
The Semantic Web & Meta Data
2009
Resource Description Framework (RDF)
Resources
Identification
URI (Uniform Resource Identifier)
Blank node (bnode, anonymous resource)
Description (Ontologies)
Extensible
RDF Schema
OWL
Rule Interchange Format
Semantic Web Rule Language
Combination of OWL and RuleML
http://www.w3.org/RDF/
The Semantic Web & Meta Data
2009
RDF Schema
Classes
Inheritance (Subclasses)
Properties
Domain (Subject)
Range (Valid Object Values)
Inheritance (Subproperties)
Types
Literal
Datatype
Label (Name)
Comment (Description)
Utility
seeAlso
isDefinedBy
http://www.w3.org/TR/rdf-schema/
The Semantic Web & Meta Data
2009
Web Ontology Language (OWL)
Species
OWL Lite
Description logic
Classification hierarchy
Basic constraints
OWL DL
Description logic
Maximal expressiveness
Computational completeness
Decidability
OWL Full
Compatibility with RDF Schema
The full monty
http://www.w3.org/TR/owl-guide/
The Semantic Web & Meta Data
2009
Web Ontology Language (OWL)
Classes
"Inheritance" with subclasses and superclasses
Properties
Datatype Properties
Object Properties
Enumeration
Instance of classes (individual items)
Operations
Union
Intersection
Complement
http://www.w3.org/TR/owl-guide/
The Semantic Web & Meta Data
2009
SPARQL
Query Language
Variables
Filters
Regular Expressions
Union
Ordering
Limits
Protocol
Web Service
WSDL 2.0
Query Results XML Format
XML vocabulary
http://www.w3.org/2009/sparql/wiki/Main_Page
The Semantic Web & Meta Data
2009
RDFa
Embedded RDF triples
XHTML only
Namespace aware
eRDF (Embedded RDF)
http://rdfa.info/
The Semantic Web & Meta Data
2009
GRDDL
Gleaning Resource Descriptions from Dialects of Languages
Triple extraction
XML / XHTML documents (not HTML)
XSLT
http://www.w3.org/TR/grddl/
The Semantic Web & Meta Data
2009
SKOS
Simple Knowledge Organisation System
RDF / RDF Schema
Controlled vocabulary
Classifying, cataloguing, grouping
SKOS Core
Index terms
Synonyms
Notes
SKOS Mapping
SKOS Extensions
http://www.w3.org/2004/02/skos/
The Semantic Web & Meta Data
2009
Friend of a Friend (FOAF)
RDF / OWL
Social networking
Profile & contact information
http://www.foaf-project.org/
The Semantic Web & Meta Data
2009
SIOC
Semantically-Interlinked Online Communities
Interconnecting discussions
Blogs
Mailing Lists
Forums
RDF / RDF Schema
Author information via FOAF
Content information via RSS
Title, created, author, content, tags, replies
http://sioc-project.org/
The Semantic Web & Meta Data
2009
Dublin Core
DCMI (Dublin Core Metadata Initiative)
Level 1 (Shared term definitions)
Shared natural-language definitions
Level 2 (Formal semantic interoperability)
Linked Data
Interoperability
Level 3 (Description Set syntactic interoperability)
Validation
Level 4 (Description Set Profile interoperability)
Common set of constraints
Use the same vocabularies
http://dublincore.org/
The Semantic Web & Meta Data
2009
Dublin Core
DCMI Metadata Terms
DCMI Namespace Policy
DCMI term declarations represented in RDF schema language
The Dublin Core Metadata Registry
Dublin Core Metadata Element Set
http://dublincore.org/
The Semantic Web & Meta Data
2009
Dublin Core Metadata Element Set
Contributor
Coverage (spatial, temporal)
Creator
Date
Description
Format (file, physical medium, dimensions)
Identifier (within given context)
Language
Publisher
Relation
Rights (property rights)
Source (derived from another resource)
Subject (keywords, classification codes)
Title
Type (nature or genre)
The Semantic Web & Meta Data
2009
DCMI Metadata Terms
abstract, accessRights, accrualMethod, accrualPeriodicity,
accrualPolicy, alternative, audience, available,
bibliographicCitation, conformsTo, contributor, coverage,
created, creator, date, dateAccepted, dateCopyrighted,
dateSubmitted, description, educationLevel, extent, format,
hasFormat, hasPart, hasVersion, identifier,
instructionalMethod, isFormatOf, isPartOf, isReferencedBy,
isReplacedBy, isRequiredBy, issued, isVersionOf, language,
license, mediator, medium, modified, provenance, publisher,
references, relation, replaces, requires, rights, rightsHolder,
source, spatial, subject, tableOfContents, temporal, title, type,
valid
The Semantic Web & Meta Data
2009
Plain Old Semantic HTML (POSH)
Awareness & education campaign
Say no to semantics abuse!
No tables for layout!
CSS for style!
Meaningful class names
Round house kick the spacer gifs!
Validate your code... ;)
The Semantic Web & Meta Data
2009
Microformats
Used in HTML and XHTML
Uses common attributes such as class, rel
Relatively well adopted
Does not use namespaces
http://microformats.org/
The Semantic Web & Meta Data
2009
Microformats
Specifications
hCalendar
hCard
rel-license
rel-nofollow
rel-tag
VoteLinks
XFN (XHTML Friends Network)
XMDP (XHTML Meta Data Profiles)
XOXO (eXtensible Open XHTML Outlines)
http://microformats.org/
The Semantic Web & Meta Data
2009
Microformats
Drafts
adr (addressing information)
geo (geographical coordinates)
hAtom, hAudio, hListing
hMedia, hNews, hProduct
hRecipe, hResume, hReview
rel-directory, rel-home
rel-payment
Support by financial or other means
rel-enclosure (caching)
robots exclusion
Ranking, indexing, archiving, anchor text
xFolk (social bookmarking)
http://microformats.org/
The Semantic Web & Meta Data
2009
Microformats
Design patterns
abbr-design-pattern
class-design-pattern
date-design-pattern
datetime-design-patternda
include-pattern
value-class-pattern
rel-design-pattern
http://microformats.org/
The Semantic Web & Meta Data
2009
The DataPortability Project
Players
Google
Facebook
Plaxo
Drupal
Netvibes
Mystrands
LinkedIn
Flickr
Six Apart
Twitter
Digg
Microsoft
http://dataportability.org/
The Semantic Web & Meta Data
2009
The DataPortability Project
RDF
RDFa
Microformats
APML (Attention Profiling Mark-up Language)
FOAF
OAuth
OpenID
OPML (Outline Processor Markup Language)
RSS
SIOC
XFN (XHTML Friends Network)
XRI (Extensible Resource Identifier)
XDI (XRI Data Interchange)
http://dataportability.org/
The Semantic Web & Meta Data
2009