Friday, January 05, 2007

TopBraid is now also an RDFa Editor

A few month back I wrote about RDFa support in our ontology editor TopBraid Composer. RDFa is a set of simple XHTML attributes being proposed by W3C, allowing web developers to add RDF/OWL metadata to existing web pages. For example, RDFa can be used to state that a certain string on a page actually is the first name of a person, and that another section on that page contains the person's date of birth. Such RDFa annotations are one way of shrinking the Meaningless Web.

Although RDFa only consists of little more than a handful of attributes, it is not always simple to combine conventional HTML content with semantic markup. RDF as well as its embedding into HTML with RDFa requires some training and should be supported by tools comparable to professional IDEs. We have been thinking about how to provide tool support to help Web page designers to work with RDFa in conjunction with HTML and JSP. Our first result is the new RDFa editing support in TopBraid. This support currently includes
  • Syntax highlighting of the RDFa keywords
  • Auto-completion of property and resource names (with CTRL-space)
  • Mouse-driven navigation from an RDFa element to the corresponding resource in the ontology (CTRL-mouse over)
  • A button to quickly extract and view the triples encoded inside the RDFa document
  • Error checking at edit-time so that unknown resource names are marked as warnings
  • A library of typical RDFa source pattern snippets
  • Drag and drop from TopBraid's ontology windows into the RDFa text area

The following image shows auto completion with geographical markup.

One mode of working with this support is to open an ontology that imports the relevant namespaces (such as FOAF or SIOC) and also includes the RDFa data source. Users can then switch between editing and browse the ontology, the HTML/RDFa source code and the resulting HTML page (click on the image for a larger version):

Needless to say that people editing RDFa this way can at any time use the TopBraid infrastructure to run reasoners, query engines or all kinds of visualizations and mashups to test how other RDFa-aware applications may work with the page. For example, if an RDFa page defines an entity with geographical coordinates, then these coordinates can be directly displayed on an embedded Google map.

This integrated development environment for RDFa is enabled by the power of the Eclipse platform. Eclipse does not only provide a windowing framework for TopBraid Composer's windows, but it also comes with many reusable components. In the case of the RDFa editor, we stand on the shoulder of giants and exploit the infrastructure of the Eclipse Web Standard Tools subproject that provides editing support for HTML, and the Eclipse J2EE Standard Tools project that adds Java Server Pages support. We have layered our RDFa support on these plugins, allowing Web developers to do incremental steps into the RDFa world from the tools they are familiar with.


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