Joining the Semantic Web: a Practical Guide.

1
Joining the Semantic Web a Practical Guide.
n

• Pasqualino Titto Assini
• Nesstar Ltd - UK

2
NESSTAR The Data Web
n
nesstar

• The Data Web is the application of Semantic Web
  techniques and principles to the problem of
  statistical data and metadata (surveys, opinions
  polls) dissemination and processing.

Nesstar - Networked Social Science Tools and
Resources
3
Joining the Semantic Web in A Few Easy(?) Steps
n
nesstar

• Know What You Want To Say ? Modelling
• Then Say It -gt Map the Model to a Semantic Web
  Language
• Think of the Future ? Managing Change
• Let Everybody Know ? Publishing on the Semantic
  Web
• Make Your Entities Behave ? Specifying
  Operations/Services

Nesstar - Networked Social Science Tools and
Resources
4
Additional Considerations
n
nesstar

• Keep it Simple Or Else ? Why Being Too Clever
  Doesnt Work on the Internet.
• XML Friend or Foe of the Semantic Web?

Nesstar - Networked Social Science Tools and
Resources
5
Know What You Want To Say
n
nesstar

• The Semantic Web is no silver bullet. It wont
  help you in modelling your data.
• Use your existing modelling language (and
  models).
• You can also use RDF/RDF Schema but
• Not many (graphical tools) tools
• Not much expressive power (example no
  relationships)
• Tip Use standard UML design tools (in most cases
  a UML Class Diagram is all you need)

Nesstar - Networked Social Science Tools and
Resources
6
Now Say It
n
nesstar

• Once you have you model you need to translate it
  to a Semantic Web Language
• Choose the target language RDF, WOL
• Define the mapping rules (might be already
  defined, UML ? RDF)
• What about using a specialised XML syntax?
• Advantage More compact/simpler syntax
• Disadvantage Difficult to design properly, need
  to define an additional mapping to RDF.
• Tip Stick to standard RDF syntax.

Nesstar - Networked Social Science Tools and
Resources
7
Managing Change
n
nesstar

• Fact of Life things change, models do as well.
• Specific Application/Clients will need to extend
  your core model.
• Good News RDF was custom made to be extensible
  (class/property inheritance, additional
  properties, reification)
• Tip Make sure that your applications can handle
  model extensions.

Nesstar - Networked Social Science Tools and
Resources
8
Publishing on the Semantic Web
n
nesstar

• Wrong assumption You need something special, a
  Registry maybe (e.g, UDDI)
• This can be real easy, just do it the WWW way.
• Self-description principle objects and types
  self-describe themselves by making accessible,
  via HTTP, their RDF description at their URL.

Nesstar - Networked Social Science Tools and
Resources
9
Specifying Behaviour
n

• Example Bank Account operations to pay in or
  draw money.
• The Semantic Web is silent on this point.
• Major oversight ? Web Services come to the
  rescue.
• Problem Web Services and the Semantic Web are
  not well integrated (but we might soon have an
  RDF model of WSDL).
• Cant wait? Use what is available DAML-S, NEOOM
  (simple RDF model of methods plus method
  invocation via HTML FORMs).

nesstar
Nesstar - Networked Social Science Tools and
Resources
10
Keep It Simple or Else
n
nesstar

• Fact The value of an information dissemination
  system depends on the quantity of information it
  contains and the number of eyeballs looking at
  it.
• Therefore initially the system is worthless (the
  Web was, the Semantic Web still is).
• But, if it starts growing it can grow real fast.
• So how do you get the snowball going? KISS to
  lure early adopters.

Nesstar - Networked Social Science Tools and
Resources
11
XML - Friend of Foe ?
n
nesstar

• (RDF/)XML is very hard to write by hand and not
  particularly pleasant to read.
• It would be very useful if people (early
  adopters) could jot down semantic web
  descriptions without tools (think of HTML).
• TBL has lately engaged in an unofficial and very
  politically incorrect activity defining a
  non-XML syntax for RDF N3.
• What about an official W3C initiative to create a
  semantic web language that is not only machine
  understandable but also easy for an human to read
  and write?

Nesstar - Networked Social Science Tools and
Resources