About the Website

About the Website

LOD2 Project Website

The LOD2 project website is built using components of the LOD2 stack, namely OntoWiki and OpenLink Virtuoso. OntoWiki already provides features like Linked Data and SPARQL endpoint support that are exposed by the site. By leveraging OntoWiki's plug-in architecture, a site extension was built that takes over requests pertaining to the given site. Thus, OntoWiki functions as a backend where content is added, removed and linked. The front-end has been styled completely independent of OntoWiki's styling.

Data Modelling

The website data basically consists of projects, partners, persons, testimonials, demos and wiki articles modelled using a combination of items from the SIOC, FOAF, and DOAP vocabularies together with a few self-defined properties. Depending on the HTTP header sent by the user agent used to access a particular resource, the information about that resource is rendered into an HTML page or returned as raw RDF data. Before doing so, the user agent is redirected to a document describing the requested resource whose address is made by adding ".html", ".rdf" or ".n3", respectively. By doing so, this behaviour is transparent to the user; he even can force a certain format being delivered by typing the respective extension into his browser's address line.

Navigation Structure

Articles describing a topic of the whole website (as opposed to a single item) are modelled as top concepts of a SKOS navigation scheme. A navigation hierarchy is formed by connecting each item to its ancestor through the SKOS broader property. A special view helper component extracts this concept hierarchy and renders it as a conventional website menu.

Content Syndication

External Web content is added to an item's description page by fetching data from news feeds or Twitter streams that are linked via the SIOC feed property. This is done on the server side in order to be able to merge more than one feed into a single stream of information. As requested by consortium members, a Wordpress blogging system has been integrated into the project website.

LOD2 website article as displayed in OntoWiki

Creating/Editing Content

Each content item's properties can be edited through OntoWiki's editing system—RDFauthor—which is developed as a separate project. Being based on Semantic Web standards like RDFa and SPARQL/Update, it is able to automatically adapt its user interface to any content being edited. By presenting editing widgets that have been created specifically for certain types of content, the user can focus on the editing task at hand and is not distracted by the complexity of the underlying data model. Below is shown a screenshot of this very article being edited in OntoWiki using the content-agnostic overlay mode. Eventually, the front-end will use RDFa as well, enabling content to be edited right in place. To this end, an in-place editing mode is currently being added to the RDFauthor system.

LOD2 website article edited in OntoWiki

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