Cover page images (keys)

Introduction to the Semantic Web

Harry Halpin, University of Edinburgh
Danny Weitzner, MIT/W3C
Oxford Internet Institute
Oxford, United Kingdom
July 2008

Overview

What is the Web?

Technical Foundations

  1. hypertext (html)
  2. hypertect protocol (http)
  3. link identifiers (uri)

The Internet vs. the Web

Message vs. Links

The Web could be implemented on top of another kind of message-routing system beside the Internet.

A Document With Links

A Links to a Mail Message

The Linked Message

A Link Back to Data (issue tracking)

And back again to report on status of issue (email as data input)

Data integrated back into issue tracking system

I want my data back

walled garden

Much of Web 2.0 is based on walled gardens, otherwise known as data warehouses

Users create content, and possibly value, often for free, but they lose control of their data and where even their data is.

Virtual Schizophrenia

ClaimID: Your data is spread throughout the online world...and mostly not under your control

claimid

Opening the Social Graph

(Some) users and developers want to stop having to re-invite their friends and to control their own data. facebook pic

Users are increasingly wanting more and more powerful applications to access their social data - and having that data behind a firewall just won't do in 2008.

The DataPortability.org to the rescue.. Danny Ayer's Video

Two Stories

Moving Data requires:
  1. The Social Graph Story: How do we actually get the social graph, merge social graphs from different services, and query graphs. RDF has the best story, so far.
  2. The Authentication Story: How can you use a single login to securely access multiple services, both to download, modify, and upload social data? OpenID is the best story with a tremendous upswing in implementation

data portability

Myspace, Facebook, and OpenSocial

Similar to "browser wars," there now are competing ways to share social graph data on the Internet.

  1. OpenSocial Alliance: Started by Google and Myspace, and endorsed by Yahoo! and virtually all the minor players in the social networking world. Open Source implementation: Shindig
  2. Facebook: The dominant player in the social networking world, has mysterious plans to offer "Facebook" connect.

The State of Play

claimid

Our Friendships Cross Social Networking Sites

worldmap of socnets

Data is Trapped Within HTML!

Applications are only as good as the data they can access.

Unfortunately, most data is trapped in idiosyncratic HTML!

or in databases behind firewalls...

Liberate the data and put it in a common universal format for accessing by our Web 2.0 applications?

The Semantic Web

... is an open world and universal space for machine-readable data.

things in documents
To a computer, then, the web is a flat, boring world devoid of meaning...This is a pity, as in fact documents on the web describe real objects and imaginary concepts, and give particular relationships between them...Adding semantics to the web involves two things: allowing documents which have information in machine-readable forms, and allowing links to be created with relationship values.
TimBL, WWW1994

URIs

The Web as a Totalizing System

Increasingly all data is on the Web: a universal information space

TimBL
This specification does not limit the scope of what might be a resource; rather, the term "resource" is used in a general sense for whatever might be identified by a URI. Familiar examples include an electronic document, an image, a source of information with a consistent purpose (e.g., "today's weather report for Los Angeles"), a service (e.g., an HTTP-to-SMS gateway), and a collection of other resources. A resource is not necessarily accessible via the Internet; e.g., human beings, corporations, and bound books in a library can also be resources. Likewise, abstract concepts can be resources, such as the operators and operands of a mathematical equation, the types of a relationship (e.g., "parent" or "employee"), or numeric values (e.g., zero, one, and infinity).
IETF RFC 3986, URI Generic Syntax,January 2005 by Berners-Lee et. al.

The Return of the Link

Hypertext links web-pages via the use of a URI at the target.

The Semantic Web just allows us to link anything that has two URIs

arrow tail, body and head are l are subject, property and value.

<http://www.example.org/Harry#> foaf:name "Harry Halpin";
<http://www.example.org/Harry#> foaf:homepage <http://www.ibiblio.org/hhalpin>.

Note the relationship to HTML links, especially with the re-discovery of the rel attribute.

Semantic web includes tables, trees...

Arrows can make a table, an arrow from each row to each value

Arrows can make a table, an arrow from each row to each value

... and tangly messes

Arrows can make a table, an arrow from each row to each value

RDF data...

a set of circles and arrows

...merges just like that.

more circles and arrows superim

Subject and object node using same URIs

Links Join Across Different Sources of Information

 Links between column headings

Verb/predicate/Property using same URIs

The Semantic Web Does Social Networks: FOAF

FOAF: Friend of a Friend - see FOAF Project

One of the earliest and most popular Semantic Web vocabularies.

FOAF RDF markup for Person, mbox, homepage, workplaceHomepage, schoolHomepage, knows and also for things that we are in or make, like primaryTopicOf and depicts. Linked in a (semantic) Web to other FOAF files and arbitrary RDF Data. Designed to be independently extended without breaking due to using RDF technologies.

Data Portability Using FOAF

FOAF

Getting Started with FOAF

You can create a FOAF file with FOAF-o-matic. There are already great tools out there, like foafnaut.

Check out Alexander Passant's foafmap.net mash-up of FOAF and Google Maps - here's me.

You can generate FOAF from Facebook profiles automatically using Matthew Rowe's FOAF Generator Facebook Application

foafnaut

We need to integrate privacy and trust issues with FOAF

You (Likely) Already Have a URI

Log-in once. No more "I forgot more password and username"! openid

OpenID is a way of a user "logging-in once" to a service provider and then having their log-in details be verified by a trusted identity provider.

Your new OpenID username is a globally-unique URI:
 href="http://openid.claimid.com/hhalpin">http://openid.claimid.com/hhalpin
ClaimID gave me an OpenID...so can many others...

Sound familiar?

Tim Berners-Lee: "The Architecture of the World Wide Web says that everything of importance deserves a URI. Go ahead and give yourself a URI. You deserve it!"

OpenID in a Picture

openid

OpenID is taking off!

See this great OpenID tutorial, from which we took this list and other details: Just the start - AOL.com now has an OpenID for everyone of their users, and Mozilla has announced OpenID support.. estimated 120 million OpenID users

Go use your OpenID (list from LifeWiki

Linked Data

linked data

The Semantic Web in Yahoo!'s Search

From Yahoo's Open Search Strategy: Without a killer semantic web app for consumers, site owners have been reluctant to support standards like RDF, or even microformats. We believe that app can be web search...we plan to support vocabulary from Dublin Core, Creative Commons, FOAF, GeoRSS, MediaRSS, and others. ... we will support RDFa and eRDF markup to embed these into existing HTML pages. yahoo semsearch

The Future

semantic web There is no technical reason why the social data in your e-mail account is kept artificially separated in your mobile phone, your social networking site, blog ...

The two questions are:

  • What will the technical solution be? (OpenID, FOAF, OpenSocial...),
  • Can the major vendors commit to one web of social data? (Can W3C help?)
  • W3C Social Web XG

    w3c

    Allows a much-looser and quicker moving form than a Working Group for exploratory purposes, allows creation of a Working Group in a year to be sped up!

    Can be a forum inside the W3C to get the diverse bodies interested in social networking communicating.

    Harmonize and stabilize relevant standards and think through privacy and identity issues with the Semantic Web.

    Anyone can join as an Invited Expert and completely open - contact me or Dan Brickley.

    If a W3C Member - interested in joining or co-sponsoring group?

    We need social scientists and social networking experts!

    Starting around October - help us create the charter on a wiki

    Parting Thoughts

    gutenberg

    I pondered all these things, and how men fight and lose the battle, and the thing that they fought for comes about in spite of their defeat, and when it comes turns out not to be what they meant, and other men have to fight for what they meant under another name.

    William Morris. A Dream of John Ball