Towards an Mda-based Approach for Development of a Structural Scope of the Presentation Layer

KRYŠTOF, J.: Towards an MDA-based approach for development of a structural scope of the presentation layer. Acta univ. agric. et silvic. Mendel. Brun., 2009, LVII, No. 6, pp. 123–132 This paper presents an approach for developing the presentation layer of so ware applications. The approach is based on the concept of the Model Driven Architecture (MDA) and uses a UML – based model of graphical user interfaces, which is created according to rules defi ned in a meta – model. The meta – model is not oriented to a particular platform, thus all designed models can be created independently of the programming language and widget library. This platform independent UML based model can be transformed into source – code for an arbitrary programming language and can be used in a so ware development process. The meta – model of our approach is an extension of the common UML and provides support for modeling the presentation layer. The meta – model thus fi lls a gap that exists in modeling three – layered so ware applications, beside the application and the data layer. By providing this possibility for modeling the presentation layer, we can crucially impact current approaches to the development of three layered so ware applications. All model artifacts contain essential information about the graphi cal user interface and can be used for a code generation. Since the UML is widely used by analysts, they can produce models which de-facto represent source code and thus they reduce the workload for programmers, who create source code by some traditional approaches. Our model – based approach also strictly separates the appearance and the structure of graphical user – interfaces and both of them are developed separately, which brings higher modularity of so ware. In this paper, we demonstrate our development approach by focusing on the structure of graphical user interfaces. Our approach is infl uenced by the concept of Model Driven Architecture and we deal with all related issues, such as meta – model, user models, model transformations and source – code generation. For evaluating our approach, we designed and developed a so ware framework, we integrated it into a generic modeling tool, and used approach principles during the development of a module of an information system. MDA, UML, modeling, presentation layer, structure, source code generation The presentation layer is not a simple homogeneous structure and it’s complexity reaches out of frame of this paper. In spite of the complexity of the presentation layer, we can defi ne it as (MYERS, ROSSON; 1992) a so ware component, that translates a user action into one or more requests for application functionality, and that provides to the user feedback about the consequences of his or her action. The defi nition refers to all visible components of a so ware application such as a window, a button or a text section and also refers to an application logic, which accesses controlling units. The application logic can determine all users’ actions with their parameters. When developing the presentation layer, we can follow two traditional approaches (RYDER, SOFFA, BURNETT; 2005): The source code for the visible component can be obtained by hard – coding, or a specialized tool can be used enabling us to get the source code by visual programming. We can