Integración de patrones en el proceso de diseño de sistemas hipermedia mediante el uso de ontologías

Abstract

Los métodos de diseño hipermedia asisten al diseñador a través de una serie de fases y productos. Sin embargo, un diseñador, tanto si es experto como no, puede llegar a tomar una solución inadecuada a un determinado problema de diseño que puede ser perjudicial para el usuario. Los patrones de diseño son ese mecanismo que puede ayudar a aliviar tanto el acometido de nuevos desarrollos como la dificultad en la toma de decisiones para la mejora de sistemas ya existentes, en tanto en cuanto puedan integrarse de forma eficiente con los métodos de diseño y sean accesibles de manera efectiva a los diferentes integrantes del equipo de desarrollo. Para resolver estas carencias, el primer objetivo de esta tesis ha sido organizar el conocimiento de los pdh, proporcionando unos criterios de clasificación, un catálogo de patrones, un lenguaje de patrones y un marco de integración con los métodos de diseño, en el cual un conjunto de pasos guían una aproximación basada en patrones que permite transformar la especificación de requisitos en entidades de diseño en el modelado conceptual, gracias a las soluciones capturadas por los patrones. Además para poder automatizar este conjunto de herramientas se ha propuesto un modelo de representación semántico basado en ontologías que permite mantener enlazada la representación textual del patrón mediante anotaciones, haciendo a los patrones mutuamente comprensibles a diseñadores y a programas.

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The development of large-scale hypermedia and web systems must be carried out following a well defined systematic process, that is, applying hypermedia and web engineering methods and techniques. In addition, considering that the development process of web systems is characterized by obtaining an operative product in a short period of time, designers can alleviate decision making resorting to design patterns. A design pattern records the knowledge and the experience of domain experts on how to make a software system more reusable and flexible as a result of many efforts on the design and codification of systems. Currently, if a designer or a developer of hypermedia applications wants to solve or to communicate a specific design problem by means of hypermedia design patterns (hdp), as starting point, she would have to search across multiple existing publications or some of web repositories available in order to identify the pattern or patterns that best fit her needs. To date, the necessary mechanisms to help the designer to find the appropriate pattern or patterns and to integrate them into hypermedia design methods do not exist. Therefore, the success of this activity will depend only on the designer knowledge about the existing resources and her experience in the use of patterns. In order to solve these lacks, the first aim of this thesis has been to organize the knowledge of hdp, providing a set of classification criteria which takes into account as much hypermedia application modeling needs as the different levels of abstraction used in the pdh literature. From these criteria, a pattern catalogue has been elaborated to facilitate the search of patterns during the resolution of particular design problems as well as a pattern language as a step-by-step guide that advises designers how to accomplish the design process from different levels of abstraction, whereas it proposes alternative problems to resolve. Finally, from the pattern language, an integration framework with design methods has been specified, in which a set of steps guides a pattern based approach to transform requirements specifications to design entities into the conceptual modeling, thanks to the solutions captured by patterns. This process has been evaluated in an empirical way to verify its validity and utility. Once the space and the knowledge of patterns are organized, new challenges and realities should be faced up to. In particular, the great amount of patterns and its different sources, even counting on the mechanisms before mentioned, lead a non-experienced des- igner in the use of patterns to the necessity to explore most of them, in addition to the effort to understand when and how the pattern must be applied. At this stage, it is worth counting on software tools that allow for the organization, recovery and exploration of patterns with searches dedicated to finding appropiate patterns to generic design problems as well as their application in other software systems, such as CASE tools. However, firstly it is necessary to share a formal specification of patterns in order to preserve compatibility among software tools. To date, the hypermedia engineering field does not have its own formalization that allows the development of software tools for patterns, and the formalizations proposed in the software engineering field only take into account the pattern solution and leave aside the textual pattern description, so important to understand the foundation that underlies pattern’s problem and solution. All elements of a pattern are required to develop effective tools for patterns organization, recovery and exploration. For example, to include the intention of pattern would allow for indexing patterns according to the problem that solve, helping users to find the appropiate pattern for a design problem. For that reason, a semantic representation model based on ontologies that combines the domain knowledge about hypermedia used for the pattern description with the pattern format has been proposed. Afterwards, this representation provides the underlying framework to complement the textual pattern representation by means of semantic annotations, which is supported by a tool that helps both users and authors of patterns to formalize their own repositories. This combination of the formal representation linked to the textual pattern representation by means of annotations allows to patterns to be mutually comprehensible by designers and programs. An example of this is the development of a semantic web repository and the automatization of the integration process of hdp in a tool support for the design of hypermedia applications, using both developments the pattern language formalized by means of the annotation tool proposed. The development of these tools have proven the technical feasibility of the solution here proposed.