RDFa From Theory to Practice
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Talk given at Institutional Web Management Workshop 2010, University of Sheffield
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RDFa From Theory to Practice
- 1. UKOLN is supported by: RDFa From Theory to Practice - Part 1 - A gentle introduction to Linked Data and the Semantic Web? 12th July 2010 Institutional Web Management Workshop 2010 University of Sheffield, UK Adrian Stevenson
- 8. So what’s happening now?
- 13. Data.gov.uk Officially launched 21 st January 2010
- 14. Data.gov.uk – search for ‘traffic’
- 15. Central Office of Information - http://coi.gov.uk/
- 16. BBC Music BETA http://www.bbc.co.uk/music/developers
- 20. Graphs house prices over time - combines house price data with information from Yahoo! Placemaker, Nestoria and OpenStreetMap
- 22. Postcode Paper - bus timetables, doctors surgeries, allotments http://blog.newspaperclub.co.uk/2009/10/16/data-gov-uk-newspaper/
- 23. Owls Near You - http://owlsnearyou.com/
- 24. 12 month project funded by JISC 2/10 jiscExpo call http://blogs.ukoln.ac.uk/locah/ http://www.twitter.com/projectlocah tag: #locah
- 26. A little bit of the techy stuff
- 37. Linked Data in Use
- 41. D2R server publishes Linked Data view of database and allows clients to query the database via SPARQL
- 56. Library of Congress Subject Headings
Notes de l'éditeur
- Screenscraping, Google algorithms, but still not ideal
- Context of openess – MPs expenses etc
- The Central Office of Information The Central Office of Information (COI) is the Government's centre of excellence for marketing and communications.
- data.gov site, which simply provides access to raw data (Excel spreadsheets, PDF files, and more), the UK is adhering closely to Berners- Lee’s Linked Data rules and making data available in formats such as RDF where feasible.
- Next few slides from demos at data.gov.uk launch Jan 21 st 2010
- Principles underpinning the technology
- Step back a bit to HTML HTML web of documents doesn’t encourage re-use, reduce redundancy. Are network effects but could be much better.
- Note this is a considerable simplification of the detail in danger of misleading. Linked data exploits semantically meaningful tagging to encourage re-use, reduce redundancy etc.
- Uses predicate logic. Goes back to Aristotle. Conceptualises things, and the relationships between things
- SparqPlug (Coetzee,HeathandMotta,2008) is a servicethatenables the extraction of Linked Data from legacy HTML documents on the Web that do not contain RDF data. The service operates by serialising the HTML DOM as RDF and allowing users to define SPARQL queries that transform elements of this into an RDF graph of their choice
- D2R - Using a declarative mapping language, the data publisher defines a mapping between the relational schema of the database and the target RDF vocabulary. Based on the mapping, D2R server publishes a Linked Data view over the database and allows clients to query the database via the SPARQL protocol.
- Just as traditional Web browsers allow users to navigate between HTML pages by following hypertext links, Linked Data browsers allow users to navigate between data sources by following links expressed as RDF triples. Linked Data search engines provide keyword-based search services oriented towards human users, and follow a similar interaction paradigm to existing market leaders such as Google and Yahoo.
- Dots indicate provenance The colour of the dots doesn’t seem to be of significance
- Falcons provide a more detailed interface to the user that exploits the underlying structure of the data. Both provide a summary of the entity the user selects from the results list, alongside additional structured data crawled from the Web and links to related entities. Falcons provides users with the option of searching for objects, concepts and documents, each of which leads to slightly different presentation of results.
- Sindice (Oren et al, 2008) and Watson () provide APIs through which Linked Data applications can discover RDF documents on the Web that reference a certain URI or contain certain keywords. The rationale for such services is that each new Linked Data application should not need to implement its own infrastructure for crawling and indexing all parts of the Web of Data of which it might wish to make use. Instead, applications can query these indexes to receive pointers to potentially relevant documents which can then be retrieved and processed by the application itself.
- Was covered at CETIS conference in 2009 I’d be interested to get any ideas on this