Semantic Web/ Future Developments

Caleb Derven,

UCD Systems Librarian

Caleb.derven@ucd.ie

IS 20090

Web 2.0 & Social Media: An Introduction

18 November 2009

What Will Be Covered

• Possible Future Directions of the Web

• The Semantic Web

• Role of Metadata and Ontologies

• Role of Semantic Modelling

• Data Models – RDF, OWL

• Issues under debate

Web 1.0

• Read Web

• Static Content

• Links

• Email/ Forms

Source: http://www.adobe.com/devnet/articles/ora_web20_architectures.html

Development of Web 2.0

• Source: http://www.frepa.org/wp/go.php?http://www.scill.de/content/2006/09/21/web-20-buzz-zeitstrahl/

What is Web 2.0

Source: http://oreilly.com/lpt/a/6228

What is Web 2.0, continued

• User-produced content

• Peer-production– Crowd-sourcing, tagging, open source

software

• Flickr, Social Software – many of the technologies and services covered in this class…

Drawbacks

• Mash-ups & Data Re-use - Recreating the Wheel?

• APIs vs. Data Models• Data Re-Usability

• Portability

• Data Migration

• Web pages/ Web services generally designed for human, not machine, consumption

Web 3.0 Characteristics

• Infrastructure for integrating (sometimes disparate) web data resources

• Use of languages developed by WC3 Semantic Activity group

• Linked & Open Data

• Formalises mashups/ joined up data

• Metadata, Metadata, Metadata

What is the Semantic Web?

• Adding machine processable meaning to World Wide Web documents

• Semantic web doesn’t replace, but extends, current web to a web of data

• Formalises what is done everyday by web users, but makes it possible for machines to do the work

What is the Semantic Web?, cont.

• “Most of the Web's content today is designed for humans to read, not for computer programs to manipulate meaningfully. Computers can adeptly parse Web pages for layout and routine processing-here a header, there a link to another page-but in general, computers have no reliable way to process the semantics”

• “The Semantic Web will bring structure to the meaningful content of Web pages, creating an environment where software agents roaming from page to page can readily carry out sophisticated tasks for users.”

• “The Semantic Web is not a separate Web but an extension of the current one, in which information is given well-defined meaning, better enabling computers and people to work in cooperation.”

Source: Berners-Lee, T., Hendler, J., & Lassila, O. (2001). THE SEMANTIC WEB. Scientific American, 284(5), 34.

Features of a Semantic Web

• Key Technologies include:• Explicit Metadata• Ontologies• Logic• Inference (rules-based systems)• Intelligent Agents

• Development of Semantic Web proceeds in layers or a stack

Semantic Web Stack

Source: http://www.w3.org/2005/Talks/1122-orf-sw/

Semantic Web – Long-Term Adoption

• Adoption of Technologies requires changes to current web

• Network Effect: Value of a service to a user arises from number of people using the service.

• Metcalfe’s Law: As the number of people in a network grows & connectivity increases, the value of the network grows; expressed as n(n-1) = O(n2)

Semantic Web – Long-Term Adoption. Cont.

Source: http://blogs.oracle.com/reynolds/2006/07/real_world_composite_services.html

Metadata and Ontologies

• Metadata refers to data about data

• Captures meaning about data

• Current Web content formulated for human rather than machine consumption– Keyword searching not great for retrieving

information– No way to distinguish between things and

between relationships in web documents

Metadata

• Knowledge Continuum

• Metadata enriches data

• Examples: tagging, library records, student records

Source: Pollock, J. T. (2009). Semantic Web For Dummies. For Dummies, 432.  

Metadata and Ontologies, cont.

• Some definitions of ontologies– “An ontology is an explicit and formal

specification of a conceptualization”– “Ontologies define the concepts and

relationships used to describe and represent an area of knowledge”

Sources: Antoniou, G., & Van Harmelen, F. (2004). A semantic web primer. The MIT Press. ; Introduction to the Semantic Web. (n.d.). . Retrieved November 16, 2009, from http://www.w3.org/2009/Talks/0829-Nanjing-IH/

Ontologies

Source: McGuinness, D. L. (2005). Ontologies come of age. Spinning the semantic web: bringing the World Wide Web to its full potential, 171.  

Ontologies

• Controlled vocabulary – catalogues

• Glossaries

• Thesauri: synonyms, narrower/ broader term relationships

• MESH: http://www.nlm.nih.gov/mesh/MBrowser.html

Semantic Modelling

• Hendler – Models assist in 3 essential ways:1. Models Help People Communicate

2. Models Explain and Make Predictions

3. Models Mediate Among Multiple View Points

Source: Allemang, D., & Hendler, J. (2008). Semantic Web for the Working Ontologist: Effective Modeling in RDFS and OWL. p. 27 Morgan Kaufmann Publishers Inc. San Francisco, CA, USA.  

Semantic Modelling

• Layers of Expressivity in Semantic Modelling

• Languages in the Semantic Web range from least expressive to most expressive: RDF, RDFS, RDFS-PLUS, OWL

Source: Allemang, D., & Hendler, J. (2008). Semantic Web for the Working Ontologist: Effective Modeling in RDFS and OWL. p. 27 Morgan Kaufmann Publishers Inc. San Francisco, CA, USA.  

Data Models for the Semantic Web - RDF

• RDF: Resource Description Framework

• Simple data model for linking and relating heterogeneous data

• Describes how object A relates to object B

• If the web is a web of data then RDF is the data format for the database

RDF

• Typical Database

• Rows represent things

• Columns represent properties

ISBN Title Author PublisherID

Pages

1439138311

Brooklyn Toibin, Colm

6543 262

1905785682

Ireland's Economic Crash: A Radical Agenda for Change

Allen, Kieran

8723 220

Source for slides 24 -31: http://www.slideshare.net/iandavis/30-minute-guide-to-rdf-and-linked-data

RDF, cont.

• The “triple” statement– basis/ building block of RDF model

• Triple consists of• Thing or subject statement describes• Properties of the thing described in the

statement• Values of the properties

Subject Value Property

RDF, cont.

• Possible to model and represent triples statements through a graph

Book Brooklyn Title

RDF, cont.

• Multiple Values

• Multiple Triples

Book Brooklyn Title

1439138311

ISBN

Author

Colm Toibin

RDF – Linked Data - URI

• URIs provide unique names in RDF

• Used to provide unique name

• Identify global address for things

• May, but aren’t required to be, addressable like URLs

• Same URI indicates identical thing

• RDF provides a model for merging data/ graphs based on URI

• Name & Identify Relations

http://example.comthing/BOOK

Brooklyn http://example.com/property/Title

1439138311

http://example.com/property/ISBN

http://example.com/property/Author

Colm Toibin

RDF – Merged Data

• Merge Data

http://example.comthing/BOOK

Brooklyn http://example.com/property/Title

1439138311 http://example.com/property/ISBN

http://example.comthing/PERSON

Colm Toibin http://example.com/property/Name

http://example.com/property/Wrote

http://example.comthing/BOOK

Ireland http://example.com/property/authored

2008 http://example.com/property/Date

http://example.comthing/BOOK

Brooklyn http://example.com/property/Title

1439138311 http://example.com/property/ISBN

http://example.comthing/PERSON

Colm Toibin http://example.com/property/Name

Ireland http://example.com/property/authored

2008

http://example.com/property/Date

RDF – Merge Data - XML<rdf: Description

rdf: about="http://example.com/thing/person">

<prop:author>Toibin, Colm</prop:name>

<prop:wrote

rdf:resource="http://example.com/thing/BOOK" />

</rdf:Resource>

<rdf: Description

rdf: about="http://example.com/thing/BOOK">

<prop:title>Brooklyn</prop:title>

<prop:date>2008</prop:date>

<prop:authored

rdf:resource="http://example.com/thing/Ireland" />

</rdf:Resource>

</rdf: Description>

RDF – Merged Data

• Retrieve data via URIs

• Query via SPARQL• SPARQL Protocol and RDF Query Language

• Merge additional data through links

Linking Open Data

• Link to Other Open Data Sets:

Source: http://linkeddata.org/images-and-posters

Linked Data – Some Examples• DBPedia: Converts Wikipedia to RDF • Creates query interfaces, ontologies,

services• http://wiki.dbpedia.org/Applications

Linked Data – Some Examples - GeoNames

• Links place names to unique URIs• http://www.geonames.org/

Data Models - OWL

• OWL – Web Ontology Language

• Builds on and extends RDF

• OWL combines European (OIL – Ontology Inference Layer) and American (DAML – DARPA Agent Markup Language) data models

OWL Encoding

• Like RDF, OWL is encoded in XML

Key OWL Functionality

• Key OWL functionality is the ability to model restrictions

• Football player playsFor specific team

• Assists in complex modelling and automated processing of data

OWL Example

• FOAF (Friend of a Friend)

• Vocabulary describing persons using RDF and OWL

• http://www.youtube.com/watch?v=LabCylbapuM&feature=player_embedded#

Current Issues

• Scale of changes required for implementation and adoption– Network effect, Metacalfe’s Law

• Trust/ Authority Layers– Verifying information, identities, etc.– Rating trustworthiness of data

• Linked/ Open Data– Who owns the data?

Semantic Web in the World

Linked Data: http://www4.wiwiss.fu-berlin.de/bizer/pub/lod-datasets_2009-03-05.html

Semantic Web Examples, cont.

• BBC Music: http://www.bbc.co.uk/music

Semantic Web Examples, cont.

• Pub Med: http://www.gopubmed.org/web/gopubmed/

Semantic Web Examples, cont.

• Talis Aspire: http://lists.lib.plymouth.ac.uk/lists/5F641268-358C-9C54-ABEB-EF372716CB6C.html

Summary

• Semantic Web is a $20 Billion Industry

• Significant uptake by industry: Oracle, IBM, SAP, Microsoft

• Significant Government Investment world-wide

Summary, Cont.

• Search Technologies (Yahoo SearchMonkey)

• Travel (TripIT)

• Social Networking (Twine) – connecting people to people vs. people to interests

Conclusions

• Semantic Web extends current web to a web of data

• This is achieved, in part, by Explicit Metadata, Ontologies, Logic, Inference (rules-based systems), Intelligent Agents

• RDF and OWL are two building blocks on the Semantic Web

Questions

Sources

• 30 Minute Guide to RDF and Linked Data. (n.d.). . Retrieved November 17, 2009, from http://www.slideshare.net/iandavis/30-minute-guide-to-rdf-and-linked-data

• Allemang, D., & Hendler, J. (2008). Semantic Web for the Working Ontologist: Effective Modeling in RDFS and OWL. Morgan Kaufmann Publishers Inc. San Francisco, CA, USA.  

• Antoniou, G., & Van Harmelen, F. (2004). A semantic web primer. The MIT Press.  • BBC - Music - Jimi Hendrix. (n.d.). . Retrieved November 16, 2009, from http://www.bbc.co

.uk/music/artists/06fb1c8b-566e-4cb2-985b-b467c90781d4• Berners-Lee, T., Hendler, J., & Lassila, O. (2001). THE SEMANTIC WEB. Scientific American, 284(5), 34. doi:

Article  • Case Study: A Linked Open Data Resource List Management Tool for Undergraduate Students. (n.d.). .

Retrieved November 16, 2009, from http://www.w3.org/2001/sw/sweo/public/UseCases/Talis/• Case Study: Improving Web Search Using Metadata. (n.d.). . Retrieved November 16, 2009, from http://www.w3

.org/2001/sw/sweo/public/UseCases/yahoo/• Data-gov Wiki. (n.d.). . Retrieved November 16, 2009, from http://data-gov.tw.rpi.edu/wiki/The_Data-gov_Wiki• Did You Know 4.0. (2009). . Retrieved September 17, 2009, from http://www.youtube.com/watch?

v=6ILQrUrEWe8&feature=youtube_gdata• Freebase - A wealth of free data. (n.d.). . Retrieved November 2, 2009, from http://www.freebase.com/• GoPubMed®. (n.d.). . Retrieved November 16, 2009, from http://www.gopubmed.org/web/gopubmed/• van Harmelen, F. (2006). Semantic Web Research Anno 2006: Main Streams, Popular Fallacies, Current Status

and Future Challenges. In Cooperative Information Agents X (pp. 1-7). Retrieved September 17, 2009, from http://dx.doi.org/10.1007/11839354_1  

• Hendler, J. (2008). Web 3.0: Chicken Farms on the Semantic Web. Computer, 41(1), 106-108.  • Hendler, J. (2009). Web 3.0 Emerging. Computer, 42(1), 111-113.  • wiki.dbpedia.org : About. (n.d.). . Retrieved November 2, 2009, from http://wiki.dbpedia.org/About

Sources

• Hendler, J., & Golbeck, J. (2008). Metcalfe's law, Web 2.0, and the Semantic Web. Web Semantics: Science, Services and Agents on the World Wide Web, 6(1), 14–20.  

• Horrocks, I., Parsia, B., Patel-Schneider, P., & Hendler, J. (2005). Semantic Web Architecture: Stack or Two Towers? In Principles and Practice of Semantic Web Reasoning (pp. 37-41). Retrieved September 17, 2009, from http://dx.doi.org/10.1007/11552222_4  

• Intro to the Semantic Web. (2007). . Retrieved September 17, 2009, from http://www.youtube.com/watch?v=OGg8A2zfWKg&feature=youtube_gdata

• Introduction to the Semantic Web. (n.d.). . Retrieved November 16, 2009, from http://www.w3.org/2009/Talks/0829-Nanjing-IH/

• Lassila, O., & Hendler, J. (2007). Embracing "Web 3.0". Internet Computing, IEEE, 11(3), 90-93.  • Linked Data | Linked Data - Connect Distributed Data across the Web. (n.d.). . Retrieved November 2, 2009, from

http://linkeddata.org/• Linked Data | Linked Data - Connect Distributed Data across the Web. (n.d.). . Retrieved November 2, 2009, from

http://linkeddata.org/• McGuinness, D. L. (2005). Ontologies come of age. Spinning the semantic web: bringing the World Wide Web to

its full potential, 171.  • OReilly, T. (n.d.). What is Web 2.0: Design patterns and business models for the next generation of software.  • OWL Web Ontology Language Guide. (n.d.). . Retrieved November 16, 2009, from http://www.w3.org/TR/owl-

guide/• Pollock, J. T. (2009). Semantic Web For Dummies. For Dummies, 432.  • RDF/XML Syntax Specification (Revised). (n.d.). . Retrieved November 16, 2009, from

http://www.w3.org/TR/REC-rdf-syntax/• RPI Map - RPI Map. (n.d.). . Retrieved November 16, 2009, from http://map.rpi.edu/index.php/RPI_Map• semanticweb.org. (n.d.). . Retrieved November 9, 2009, from http://semanticweb.org/wiki/Main_Page

Sources

• Shirky, Clay. (n.d.). Shirky: Ontology is Overrated -- Categories, Links, and Tags. Retrieved September 17, 2009, from http://www.shirky.com/writings/ontology_overrated.html

• The Ubiquitous Web (1). (n.d.). . Retrieved November 9, 2009, from http://www.w3.org/2005/Talks/0621-dsr-ubiweb/#(1)

• Thomas Gruber. (n.d.). Ontology of Folksonomy: A mash-up of apples and oranges. International Journal on Semantic Web and Information Systems, 3(2). Retrieved September 17, 2009, from http://tomgruber.org/writing/ontology-of-folksonomy.htm  

• TSO (The Stationery Office). (2007, May 16). Data Re-use. Retrieved November 16, 2009, from http://www.london-gazette.co.uk/reuse

• Web Squared: Web 2.0 Five Years On - by Tim O'Reilly and John Battelle. (n.d.). . Retrieved November 15, 2009, from http://www.web2summit.com/web2009/public/schedule/detail/10194