Multi Agent Semantics Web Systems: Overview
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Multi Agent Semantics Web Systems: Overview
Ewan Klein
School of Informatics
MASWS — 16 January 2012
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 1 / 40
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.. .1 Practical Issues
Topics
Exam and Assigments
Reading
.. .2 MASWS: Diving Into the Semantic Web
High-Level View
Semantics?
Linked Data
Mashups
Outlook
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 2 / 40
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Background
Platform-specific (Windows, Linux, MacOS, …) apps vs.
web/browser-as-platform/cloud + interoperability
Data deluge
Web 1.0, Web 2.0, …
Web as an unpredictable, risky and dynamic software environment
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 3 / 40
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Key Topics and Challenges
Weeks 1–5 [Ewan]
Infrastructure for connecting web-scale data at the semantic level
Representing and reasoning with semantics at web-scale
Weeks 7–11 [Michael]
Exposing applications and agents on the web as services
Using agent models to support communication and coordination for web
services
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 4 / 40
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Coverage
For the Semantic Web (SW), we’ll mainly focus on Resource Description
Framework (RDF) and associated technologies / tools.
Although OWL (Web Ontology Language) is an important part of SW, we
don’t have time to look at it properly.
emphasis on Semantic Web than Multi Agent Sytems — integration of the
two still an open research question.
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 5 / 40
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Assessment
Written exam, 70%
Coursework assignments, together worth 30%
▶ Two major assignments, plus one additional small assignment for MSc
students
Exam will only test material from lectures (including guest lectures), from
coursework and from required reading.
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 6 / 40
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Assessment
Written exam, 70%
Coursework assignments, together worth 30%
▶ Two major assignments, plus one additional small assignment for MSc
students
Exam will only test material from lectures (including guest lectures), from
coursework and from required reading.
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 6 / 40
. . . . . .
Assessment
Written exam, 70%
Coursework assignments, together worth 30%▶ Two major assignments, plus one additional small assignment for MSc
students
Exam will only test material from lectures (including guest lectures), from
coursework and from required reading.
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 6 / 40
. . . . . .
Assessment
Written exam, 70%
Coursework assignments, together worth 30%▶ Two major assignments, plus one additional small assignment for MSc
students
Exam will only test material from lectures (including guest lectures), from
coursework and from required reading.
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 6 / 40
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Coursework Assignments
Not just a way of tormenting you — crucial for really understanding the
material.
You will be expected to do some programming as part of the
assignments, but language is up to you.
New: the two major assignments will be carried out in teams.
By default, credit will be split equally amongst team members.
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 7 / 40
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Reading
The lecture slides are not a text book!
No single book covers the scope of the course, but two main texts:
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 8 / 40
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Other Books
Bob DuCharme.
Querying and Updating with SPARQL 1.1.
O’Reilly Media, 2011. In-depth guide to the standard semantic web query languagexs
Grigoris Antoniou and Frank van Harmelen.
A Semantic Web Primer, 2nd Edition.
MIT Press, 2008. Quite detailed presentations of XML, RDF and OWL.
Thomas B. Passin.
Explorer’s Guide to the Semantic Web.
Manning, 2004. Less technical than Antoniou & van Harmelen, but covers more topics.
Christopher Walton.
Agency and the Semantic Web.
Oxford University Press, 2007. Good coverage of MAS and their relevance to the Semantic
Web
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 9 / 40
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Lecture Schedule on Course Webpage
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 10 / 40
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Reading outside the box
There is lots of relevant literature available online — try to explore some
of it!
Also a lot of informal discussion in Twitter, portals, newsgroups, blogs,
etc.
Help create a dynamic resource on the MASWS Wiki:
http://sites.google.com/site/masws09/
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 11 / 40
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Let’s dive in!
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 12 / 40
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Document Web
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 13 / 40
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TBL: I have a dream
I have a dream for the Web [in which computers] become capable of
analyzing all the data on the Web –– the content, links, and
transactions between people and computers.
…the day-to-day mechanisms of trade, bureaucracy and our daily
lives will be handled by machines talking to machines.
Tim Berners-Lee (1999) Weaving the Web
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 14 / 40
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TBL: The Data Web
I don’t think [the Semantic Web is] a very good name but we’re stuck
with it now. The word semantics is used by different groups to mean
different things.
…I think we could have called it the Data Web. …it connects all
applications together or gives [people] access to data across the
company …
Tim Berners-Lee (2007), Interview in Business Week
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 15 / 40
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Semantic Web
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 16 / 40
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The ‘semantics’ in Semantic Web
Syntax / semantics distinction: long history in philosophy of language,
linguistics, formal logic
Simple view:▶ syntax concerned with arrangement of symbols▶ semantics concerned with relation between symbol strings and the world
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 17 / 40
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Dublin Core: Commonly understood semantics
Discovery of information across …the Internet is hindered by
differences in terminology and descriptive practices from one field of
knowledge to the next. The Dublin Core can help the ”digital tourist”
…by supporting a common set of elements, the semantics of which
are universally understood and supported. For example, scientists
concerned with locating articles by a particular author, and art
scholars interested in works by a particular artist, can agree on the
importance of a “creator” element. Such convergence on a common,
if slightly more generic, element set increases the visibility and
accessibility of all resources, both within a given discipline and
beyond.
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 18 / 40
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Dublin Core: Creator
URI: http://purl.org/dc/elements/1.1/creatorLabel: Creator
Definition: An entity primarily responsible for making the resource.
Comment: Examples of a Creator include a person, an organization, or
a service. Typically, the name of a Creator should be used
to indicate the entity.
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 19 / 40
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Scenario
What are you doing on Burns night?
⇒ Google “burns”
⇒ Wikipedia article on Robert Burns
⇒ Amazon listing of books by Burns
⇒ Google Maps to look at birthplace of Burns
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 20 / 40
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Scenario
What are you doing on Burns night?
⇒ Google “burns”
⇒ Wikipedia article on Robert Burns
⇒ Amazon listing of books by Burns
⇒ Google Maps to look at birthplace of Burns
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 20 / 40
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Scenario
What are you doing on Burns night?
⇒ Google “burns”
⇒ Wikipedia article on Robert Burns
⇒ Amazon listing of books by Burns
⇒ Google Maps to look at birthplace of Burns
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 20 / 40
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Scenario
What are you doing on Burns night?
⇒ Google “burns”
⇒ Wikipedia article on Robert Burns
⇒ Amazon listing of books by Burns
⇒ Google Maps to look at birthplace of Burns
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 20 / 40
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Scenario
What are you doing on Burns night?
⇒ Google “burns”
⇒ Wikipedia article on Robert Burns
⇒ Amazon listing of books by Burns
⇒ Google Maps to look at birthplace of Burns
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 20 / 40
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Google Query
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 21 / 40
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Wikipedia Article (Scotland::Culture)
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 22 / 40
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Amazon
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 23 / 40
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Google Maps
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 24 / 40
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Combining Information
Wikipedia Amazon Google Maps
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 25 / 40
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A Mashup
Wikipedia Amazon Google Earth
Web Page
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 26 / 40
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Web APIs
A large and growing number of web data sources provide
program-accessible interfaces (APIs).
The web site http://www.programmableweb.com currently lists 4,796
(2009: 1,556) APIs and 6,401 (2009: 4,506) Mashups.
Most popular Web APIs:
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 27 / 40
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Limitations of Web APIs
The interfaces are non-uniform — REST, RPC (e.g. SOAP) and hybrid
The results are returned in a variet of formats — XML, JSON, Atom
The data schemas tend to be provider-specific
Militates against the development of portable, generic methods of
accessing and using data
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 28 / 40
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Document Web
Provide globally unique addresses for web documents: URLs
Enable all web documents to be accessible over HTTP
Use a standard format for web documents: HTML
Link between documents: HREFs
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 29 / 40
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Semantic Web
Provide globally unique identifiers for things
Enable all data to be accessible over HTTP
Use a standard format for data
Use standardized schemas / vocabularies
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 30 / 40
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Semantic Web
Provide globally unique identifiers for things: URIs
Enable all data to be accessible over HTTP: HTTP URIs
Use a standard format for data: Resource Description Framework (RDF)
Use standardized schemas / vocabularies: FOAF, Dublin Core, SIOC, …
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 31 / 40
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Linked Open Data
As before, plus:
When a person or application looks up a URI, they get back some
informative RDF
Include statements that link one dataset to another
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 32 / 40
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RDF Graphs
books:1855349825
dbpedia:Robert_Burns
dc:creator
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 33 / 40
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RDF Graphs
books:1855349825
dbpedia:Robert_Burns
dc:creatorbooks:1855349825
http:www.amazon.com
bm:hasOffer
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 34 / 40
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RDF Graphs
books:1855349825
dbpedia:Robert_Burns
dc:creator
http:www.amazon.com
bm:hasOffer
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 35 / 40
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RDF Mashup
Wikipedia Amazon Google Earth
Web Page
SPARQL
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 36 / 40
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Linked Open Data Cloud
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 37 / 40
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Lee Feigenbaum: Commercial Arguments for Semantic Web
Targets of semantic web are familiar:▶ data integration,▶ data inference,▶ data classification,▶ data visualization
Traditional tools can be used, but process is often too hard /
time-consuming
RDF lets you build things fast because models can evolve incrementally
http://www.thefigtrees.net/lee/blog/2011/09/saving_months_not_milliseconds.html
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 38 / 40
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The Semantic Markup Bottleneck
How do we get enough data + schemas to obtain a ‘network effect’?▶ Open data, open government: data.gov.uk, data.gov.us, …▶ Text processing of unstructured data
Tim Berners-Lee LOD Example:
data on health care expenditures for a given geographical area
data about the health and lifestyle characteristics of the population of that
region
⇒ assess effectiveness of the government programme
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 39 / 40
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Reading for this Week
...1 Tim Berners-Lee, Jim Hendler and Ora Lassila (2001) ‘The Semantic Web.’
Scientific American, Vol. 284, pp. 34–43.
...2 Nigel Shadbolt, Wendy Hall, Tim Berners-Lee (2006). ‘The Semantic Web
Revisited.’ IEEE Intelligent Systems.
PDF versions available from course web page.
Ewan Klein (School of Informatics) Multi Agent Semantics Web Systems: Overview MASWS — 16 January 2012 40 / 40
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