Wednesday, May 30, 2007

Default Namespaces considered harmful

In RDF, default namespaces are typically used to minimize the length of resource names. For example, if you have a resource and define everything up to the # as your default namespace, then you can abbreviate the whole URI with "Haferflocken" only.

While this is very convenient in simple ontologies, things become quickly very confusing if you are building modular ontologies that span multiple namespaces and files. For our NASA work, we are dealing with ontologies that consist of 80 or more modules, all of which have their own namespaces. In such settings, using default namespaces is problematic because the same resources will be called under different names when you switch between files. For example if you are working in SPARQL and store your queries as part of a string-based query library, then the queries may reference resources sometimes as :Haferflocken and sometimes as aldi:Haferflocken, depending on whether a namespace is used or not. Depending on which is the main file, the queries may not work. Another problem is that if only a default namespace exists, and another file imports your ontology, then it is unclear what prefix to use for the external namespace. This leads to situations in which the same namespace is sometimes abbreviated "aldi" and sometimes "products".

Our recommended practice is to not use any default namespaces, but instead explicitly declare a prefix for that namespace inside of the file so that when someone wants to import your model you all have consistent namespaces. This prepares your models to be imported in a modular fashion down the road.

Semantic Technology Conference Photos

Back to normal life after last week's busy Semantic Technology Conference. For those who could not attend, Keefe has kindly uploaded some photos from the various TopQuadrant-related events:

Wednesday, May 23, 2007

TopBraid Suite presented at SemTech 2007

Yesterday we presented the new TopBraid Live and TopBraid Ensemble products at the Semantic Technology conference. The room was packed full (and, more importantly, nobody left during the talk), so I guess we are going in the right direction. There were also excellent networking opportunities at the exhibition, which continues today.

Here are the slides of my presentation - thanks to all who attended:

Some more information on the new TopBraid Suite products is available from the TopQuadrant web site. I'll write more about it over the next couple of weeks.

Thursday, May 10, 2007

TopQuadrant is hiring!

Most people at TopQuadrant are currently busy preparing for the upcoming Semantic Technology Conference in San Jose. This will be a great event for us, since we will introduce a new family of products under the umbrella of the TopBraid Suite. After we have quite successfully established TopBraid Composer as the leading professional semantic application development tool, we now take the next step.

We will introduce TopBraid Live as a client-server platform and library of reusable building blocks for all kinds of Semantic Web applications. This includes typical mash-up components (such as maps and calendars) but also more complex widgets such as trees, forms, reports and charts. Support for semantic search and other standard tasks will be integrated as well. We also introduce TopBraid Ensemble as an out-of-the-box solution for viewing and editing RDF/OWL instances with a thin AJAX-based Web client. Needless to say, all these Web applications are seamlessly integrated with each other. For example, you can use TopBraid Composer to define form layouts and get exactly the same layout in TopBraid Ensemble. Be sure to visit us at our booth to find out more.

In order to nurture and support all these new products and other customer projects, we are now looking for new developers. In addition to a good command of the underlying RDF-based technologies, candidates need to have excellent Java and Web development skills. If you are able to relocate, then sunny California is the place to be. TopQuadrant is in the middle of a solid phase of growth, and I think we are very well-positioned to become an important player in the semantic technology field. If you are interested in joining us (or know someone who might have a matching profile), please drop me a line.