Getting started with RDF

So you have seen Kevin Kelly's presentation on the next 5000 days of the web? You don't believe in magic, and you want to see how it can really work? This used to be quite difficult, but it has become a lot easier recently. Here are some pointers I will try to keep up to date.

Introductory Material

Read Dean Allemang and Jim Hendler's Book "The Semantic Web for the Working Ontologist". While you are waiting for that book to arrive you can already view and listen to Dean Allemang's excellent presentation at JavaOne 2008. If you are interested in Social Networking, then you could follow that up also with my JavaOne presentation that same year which goes more into the RESTful, self describing web, hyperdata side of things, ie the Web in the Semantic Web.

One should also remember that one does not need to trust everything one finds on the web. A good semantic web engine will allow you to merge different graphs depending on which ones you trust, which will indeed be something partly subjective, but which can also evolve. The semantic web allows you to change your mind. Good reasoning engines to help make that fast are only just appearing though.

References

A lot of the references on the W3C use the original RDF XML syntax, which happens to be somewhat unintuitive to use and leads people to think too syntactically about the semantic web. XML developers may feel tempted to take out their XML tools, which may not get them what they were looking for. Recently a non official Semantic Web primer was put together that uses the much easier to use Turtle notation, the one the SPARQL query language is inspired from.

Tools

It is good to use different tools, as each have their own advantages. There are too many ( see the sweet tools listing ) for anyone to try them all out. Here are the one's I use regularly:

  • the cwm python script, does a lot of useful things. Just downloading RDF/XML , following redirects, etc, and transforming it to your preferred format (Turtle) can be extremely useful. It also has a resoning engine, has rules, and can be set up and queried with SPARQL.
  • For my programming tasks, as I am a Java developer, I use Sesame 2. It is a Java framework that has a large following. It's competitor in the Java space is the HP backed Jena, which has better out of the box inferencing support.
  • If you want to quickly view your SQL database as an RDF store I recommend D2RQ. It has not been evolving much recently though.
  • The Tabulator Firefox plugin, turns Firefox into a generic RDF browser. It is a prototype, but is very useful.

Comments:

First of all - thanks this is a very useful article for many of us...

Although this is a shameless plug for our admittedly commercial product - if you do want to add a semantic web to Oracle and/or any other structured data sources including Excel Spreadsheets and Web Services - please consider taking a look at http://www.semanticbusinessintelligence.com - which is a "trailer" site for The Semantic Discovery System - which goes way beyond D2RQ - and is being implemented at large corporate sites, and is in ongoing development...

Ian Goldsmid

Posted by Ian Goldsmid on September 02, 2008 at 03:03 PM CEST #

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