The document discusses the Semantic Web and how it provides a common framework to share and reuse data across applications and organizations. It describes Resource Description Framework (RDF) and how it represents relationships in a simple data structure using graphs. It also discusses Linked Data design principles and standards like RDFa and Microformats that embed semantics into web pages. Finally, it provides examples of how search engines like Google and Yahoo utilize structured data from RDFa and Microformats to enhance search results.
1. Semantic Web, RDFa & Microformats Tim Dennis Research Technologist Data Lab Emerging Tech Lightning Talks UC Berkeley Library
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5. “The Semantic Web provides a common framework that allows data to be shared and reused across application, enterprise, and community boundaries” (World Wide Web Consortium, 2008a)
6. RDF 1. Resource Description Framework 2. Presents relationships in a simple data structure 3. We can draw graphs of those relationships 4. We can represent those relationships in multiple formats for computers --Tim Berners-Lee, Linked Data - Design Issues. http://www.w3.org/DesignIssues/LinkedData.html
7. Design Principles 1. Use URIs for names of things 2. Use HTTP URIs so people can look up those names 3. Provide useful information in standard formats at those URIs 4. Include links to other URIs so people can discover more things --Tim Berners-Lee, Linked Data - Design Issues. http://www.w3.org/DesignIssues/LinkedData.html
46. 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
47. Simile Exhibit – Faceted view of structured data. < http://simile-widgets.org/exhibit/examples/nobelists/nobelists.html>
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Notes de l'éditeur
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: &quot;This simple idea, however, remains largely unrealized.&quot; – 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 core technology is RDF. Resource Description Framework Expresses data in a Subject-Predicate-Object form So, Tim love ice cream, Tim hates pickles In 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
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.
Example RDF – Friend of a Friend file
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
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.
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.