Component Based Integration of Presentation, Data Access and Application Logic

The maturity of Web enabled architectures together with the rapid advances of XML has lead to the separation of: (i) presentation; (ii) data access; and (iii) application logic. This has greatly streamlined the specifications, design, implementation, maintenance and life cycle support of applications. Indeed the cornerstone of this approach is the earliest and maximal separation between (i)-(iii). The present paper promotes the view that the experience gathered and the maturity of current solutions and products can indeed allow us to reconsider this trend and rejoin well defined generic functions of (i), (ii) and (iii) into self-contained reusable components. The final application will then consist of a tool assisted instantiation of such components. A rich parameterization of these components will meet most of the requirements of the application logic. Integrating the presentation, data access and (a large part of) the application logic, is not directly opposed to the separation principle mentioned above. The integration suggested entails only the generic elements of a GUI, of the data base access operations as well as well commonplace application logic structures. Standard transformation technologies (e.g. XSLT) and ways of conglomeration resources (e.g. XLink) ensure their deployment in different processing, data base and display environments. The choice of the component level communication environment determines the character, technology and business prospective of the solution. With that being the http level, we obtain a wholly Web enabled distribution at components level. The paper examines this proposition from the methodological point of view and presents some examples