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


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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


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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


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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.


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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.


. . . . . .

Assessment

Written exam, 70%

Coursework assignments, together worth 30%

▶ Two major assignments, plus one additional small assignment for MSc

students




. . . . . .

Assessment

Written exam, 70%

Coursework assignments, together worth 30%▶ Two major assignments, plus one additional small assignment for MSc

students




. . . . . .

Assessment

Written exam, 70%

Coursework assignments, together worth 30%▶ Two major assignments, plus one additional small assignment for MSc

students




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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.


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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:


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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


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Lecture Schedule on Course Webpage


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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/


http://sites.google.com/site/masws09/

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Let’s dive in!


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Document Web


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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


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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


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Semantic Web


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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


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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.


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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.


http://purl.org/dc/elements/1.1/creator

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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


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Scenario







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Scenario







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Scenario







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Scenario







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Google Query


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Wikipedia Article (Scotland::Culture)


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Amazon


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Google Maps


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Combining Information

Wikipedia Amazon Google Maps


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A Mashup

Wikipedia Amazon Google Earth

Web Page


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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:


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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


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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


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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


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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, …


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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


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RDF Graphs

books:1855349825

dbpedia:Robert_Burns

dc:creator


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RDF Graphs

books:1855349825


dc:creatorbooks:1855349825

http:www.amazon.com

bm:hasOffer


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RDF Graphs

books:1855349825


dc:creator

http:www.amazon.com

bm:hasOffer


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RDF Mashup

Wikipedia Amazon Google Earth

Web Page

SPARQL


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Linked Open Data Cloud


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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


http://www.thefigtrees.net/lee/blog/2011/09/saving_months_not_milliseconds.html

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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


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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.


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