Using Semantic Web technologies for building Web Information Systems (Hera)

Background:

The primary focus of the Hera project [Hera] is to support the design and implementation of Web Information Systems (WIS). It is a model-driven methodology that distinguishes three different steps: the integration/retrieval of the data that needs to be presented, the wrapping of the integrated/retrieved data in the application logic, and the data presentation on different displays for different types of users.

Semantic Web [SemWeb] technologies like RDF(S) [RDF] proved to be very useful in the specification of the different Hera models. Lacking a transformation language for the Semantic Web, an XSLT [XSLT] processor/Java-based [Java] software were used to process different model instances.

A characteristic aspect of modern WIS is their ability to support presentation adaptation based on user preferences and device capabilities (adaptability). Besides this static adaptation, the presentation can be modified dynamically according to the user's state of mind while browsing the presentation (adaptivity).

Problem:

The Hera Presentation Generator [HPG] is a tool that illustrates how one can build WIS using the Hera methodology. It shows the usefulness of the RDF(S)-based models Conceptual Model (CM), Application Model (AM), and Presentation Model (PM) in the automatic generation of hypermedia presentations from high-level presentation specifications. There are two versions of the HPG: 1.0 in which a hypermedia presentation is pre-computed outside a Web server, and 2.0 in which hypermedia pages are computed on demand on a Web server.

The Hera methodology needs to be extended in order to support adaptivity (changing the presentation while the user is browsing it) and to treat a larger set of media types (like video and audio). While the static adaptation of the presentation is captured in visibility conditions attached to CM/AM/PM elements, the ability to generate adaptive hypermedia presentations is not yet explored.

Advanced Semantic Web specification and transformation languages should be considered in developing a newer version of the HPG which implements the above requirements.

Task:

In the first phase the HPG 2.0 should be adapted in order to be able to generate adaptive hypermedia presentations. Special attention will be given to the specification of adaptivity aspects in the Hera models. As inspiration, the previous work done with AHA! [AHA!] (which generates adaptive hypermedia presentations from a given set of resources; in Hera these resources are not known in advance) can be used. The adaptivity rules can be specified with Web rule languages like RuleML [RuleML] or SWRL [SWRL]. Also the HPG should be extended (at this moment it supports links and only two media items: text and image) with different media items (video and audio).

In the second phase, the HPG should be upgraded to use OWL [OWL] instead of RDF(S) as the different models: CM, AM, and PM can benefit from a Web ontology representation. The Jena framework [Jena] can be used in dealing with OWL representations. In case that an OWL query language is not yet available, the RQL query language [Sesame] can be used (maybe in conjunction with XSLT [XSLT]) in the different Hera transformations to better exploit the available knowledge.

In the fourth phase the HPG should be extended to make use of Web services [WS] for providing input data to the system as well as decomposing the HPG in different Web services, each providing a specific WIS functionality (getting the right data, structuring the data in a presentation abstraction, performing presentation adaptation, building

the presentation in a browser specific format etc.).

If time permits, the results obtained in the second phase should be generalized by defining a declarative transformation language for RDF/OWL representations.

The programming language to be used is Java [Java], Jena and Sesame are available as Java libraries.

Information: Flavius (F.) Frasincar

References:

[AHA!]

http://aha.win.tue.nl/

[Hera]

http://wwwis.win.tue.nl/~hera/

[HPG]

http://www2004.org/proceedings/docs/2p242.pdf

[Java]

http://java.sun.com/

[Jena]

http://www.hpl.hp.com/semweb/jena.htm

[RDF]

http://www.w3.org/RDF/

[SemWeb]

http://www.w3.org/2001/sw/

[Sesame]

http://sesame.aidministrator.nl

[OWL]

http://www.w3.org/2001/sw/WebOnt/

[RuleML]

http://www.ruleml.org/

[SWRL]

http://www.w3.org/Submission/2004/SUBM-SWRL-20040521/

[WS]

http://www.w3.org/2002/ws/

[XSLT]

http://www.w3.org/TR/xslt