Semantic Web, RDFa & Microformats

Tim DennisResearch TechnologistData LabEmerging Tech Lightning TalksUC Berkeley Library

Current web has problem with data integration across the web. http & browsers separated data transport from web apps

Data stovepiped: integration, aggregation & reuse difficult

Tim Berners Lee In 2001 wrote about vision of the evolution of the existing Web to a Semantic Web. Recently TBL: "This simple idea, however, remains largely unrealized." The Semantic Web Revisited, Intelligent Systems IEEE, Lee, Shabolt, & Hall < http://ieeexplore.ieee.org/xpl/freeabs_all.jsp?arnumber=1637364 >

* rdf encodes the semantic web, vocabularies are written in it* Sparql RDF query language and RDF dbs (triple stores)* OWL is the WEB ontology language used for defining precise relationships b/t model elements (e.g. owl:sameAs)

The Semantic Web provides a common framework that allows data to be shared andreused across application, enterprise, and community boundaries(World Wide Web Consortium, 2008a)

RDF1. Resource Description Framework2. Presents relationships in a simple datastructure3. We can draw graphs of those relationships4. We can represent those relationships inmultiple formats for computers

--Tim Berners-Lee, Linked Data - Design Issues. http://www.w3.org/DesignIssues/LinkedData.html

The core technology is RDF.Resource Description FrameworkExpresses data in a Subject-Predicate-Object formSo, Tim love ice cream, Tim hates picklesIn a relational db world the relationship b/c tables might be semantic This is one of that but its not encoded into the actual data. RDF does that the relationship b/t the objects is spelled out within the code and subsequently machines can read and act on this. SemWeb often called Giant Global Graph

Design Principles1. Use URIs for names of things2. Use HTTP URIs so people can look upthose names3. Provide useful information in standardformats at those URIs4. Include links to other URIs so peoplecan discover more things

--Tim Berners-Lee, Linked Data - Design Issues. http://www.w3.org/DesignIssues/LinkedData.html

Another essential principle of semweb is that it use URIs for names of things (uniform resource identifier)

This disambiguates similar people/places/things based on the uniqueness of the uri. A uri for john smith on a berkeley domain would be different from john smith on a stanford domain.

FOAF

RDF Example: http://www.w3schools.com/rdf/rdf_example.asp

Example RDF Friend of a Friend file

Linked Data: http://linkeddata.org/

Organizations are not only publishing their data in RDF, but are exposing the data as linked data which interconnect the RDF with other RDF stores So Dbedia uses the wordnet links for defining words etc.Linking Open Data

http://id.loc.gov/authorities/

Recent example of exposing linked data as RDF is the Library of congress Subject headings. On this site you can download the RDF for the LCSH

It has a RESTful web service that you can program to.

And it has a human interface where you can search and exlpore.

http://id.loc.gov/authorities/

An example of a graph of the terms on LCSH. Provides a nice visualization of the concepts. This is a major step b/c it mean that the LCSH now has URIs associated with the concepts which can be used to link up previously unconnected data on the web.

RDFa & Micoformats

Embeds semantics into existing XHTML

Annotates XHTML web pages with RDF (RDFa)

Mix of human readable & machine readable

RFDa uses CURIE a way to prefix an inline namespace (amazonisbn: 0596153813)

More large services are publishing Microformats (been around longer) linkedin, digg

Microformats

Events information - hCalendar.

People or organisations - hCard.

Geocode - Geo.

Copyright license - rel=license.

Social networking data - XFN

Tagging - rel=tag or xFolk.

Lists - XOXO.

Reviews - hReview.

http://microformats.org/

RFDa Vocabularies

Geo

FOAF

Dublin core

RDF Calendar

Beer & Wine Ontology

Resume

Many many more at schemaweb.info

RDFa Primer: http://www.w3.org/TR/xhtml-rdfa-primer/

Google Rich Snippets

Microformats & RFDaReviews

People

Products

Businesses and organizations

Yahoo! SearchMonkey

Accepted RDFa Vocabulary (you can also define own)Dublin CoreDocument metadata

Friend-Of-A-FriendPersonal profiles and social networks

VCardPersonal and business addresses

VCalendarEvents and other calendar items

hReviewReviews

SIOCBlogs, discussion forums, Q&A sites

GoodRelationsProduct price specification, delivery and payment etc.

DBPediaGeneric vocabulary

FreebaseGeneric vocabulary

Yahoo! Search results

Google search results

RDFa & Microformat Enhanced Search Results

RDFa Review Markup

Microformat hReview Markup

MIT's Simile Exhibit Structured data web publishing tool. Can consume RDF. Example below is of the timeline widget. < http://www.simile-widgets.org/exhibit/ >

Music Composer Database: http://www.musicedmagic.com/Exhibit/composers.html

Simile Exhibit Faceted view of structured data. < http://simile-widgets.org/exhibit/examples/nobelists/nobelists.html>