Design and Development of Component-based Adaptive Web Applications

Dissertation

zur Erlangung des akademischen Grades Doktoringenieur (Dr.-Ing.)

vorgelegt an der
Technischen Universität Dresden
Fakultät Informatik

eingereicht von
M.Sc. Zoltán Fiala
geboren am 19. März 1977 in Budapest

Abstract

The WWW is rapidly evolving to a ubiquitous information and application medium. Formerly a collection of static HTML pages, today’s Web sites are complex Web Information Systems offering large amounts of content and functionality. Their growing audience is characterized by heterogeneous goals, preferences, and capabilities. Furthermore, people access the Web from a diversity of locations and devices. These trends necessitate adaptive Web sites that automatically adjust their content, navigation, and presentation to their usage context.
This need for adaptation implies additional requirements for the already complex development process of Web applications. Still, even though current Web design methods already address limited adaptation issues at design time, existing Web document formats do not provide a sufficient implementation base for structured adaptation engineering. The missing support for a clear separation of different application and adaptation concerns prevents the efficient reuse of configurable implementation artefacts for different platforms and contexts.
This dissertation addresses the aforementioned shortcomings by combining the benefits of model-based Web design methods with the advantages of component-based implementation techniques for efficiently engineering adaptive Web sites. The main goal is the intuitive compositionofcontext-dependentWebapplicationsfromdeclarative, reusable, andadaptable components, aided by a systematic development process and appropriate tool support.
After a thorough review of related Web engineering approaches, a novel, concern-oriented component model is presented for adaptive Web applications. It is based on the notion of declarative document components that encapsulate separate application and adaptation aspects (e.g. content, structure, navigation, semantics, presentation) on different abstraction levels. Document components contain inherent adaptation rules, allowing to realize numerous hypermedia adaptation techniques. Composed to complex document structures, they can be automatically published to different output formats and client platforms, adapted to the current usage context. For the systematic development of component-based adaptive Web applications a multi-stage, model-based authoring process and a visual authoring tool are presented. The resulting engineering process supports different kinds of static and dynamic adaptation at both design and implementation level. Its practical applicability for the systematic development of dynamic multimedia Web Information Systems is demonstrated and thus constructively validated by number of application prototypes. Finally, it is investigated how the lessons learned from authoring component-based adaptive Web applications can be applied to adapt already existing legacy Web-based systems. As a generalization of the proposed component-based approach, the Generic Adaptation Component is presented for decoupling and adding selected adaptation concerns to XML-based Web applications.

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