UML-based web engineering: An Approach Based on Standards

Abstract

7.1 OVERVIEW UML-based Web Engineering (UWE; www.pst.ifi.lmu.de/projekte/uwe) came up at the end of the 1990s (Baumeister et al., 1999; Wirsing et al., 1999) with the idea to find a standard way for building analysis and design models of Web systems based on the then-current methods of OOHDM (Schwabe and Rossi, 1995), RMM (Isakowitz et al., 1995), and WSDM (de Troyer and Leune, 1998). The aim, which is still being pursued, was to use a common language or at least to define meta-model-based mappings among the existing approaches (Koch and Kraus, 2003; Escalona and Koch, 2006). At that time the Unified Modeling Language (UML), which evolved from the integration of the three different modeling techniques of Booch, OOSE, and OMT, seemed to be a promising approach for system modeling. Since those early integration efforts, UML became the " lingua franca " of (object-oriented) software engineering (Object Management Group, 2005). A prominent feature of UML is that it provides a set of aids for the definition of domain-specific modeling languages (DSL)—so-called extension mechanisms. Moreover, the newly defined DSLs remain UML-compliant, which allows the use of all UML features supplemented, e.g., with Web-specific extensions. Both the acceptance of the UML as a standard in the development of software systems and the flexibility provided by the extension mechanisms 158 N. Koch et al. are the reasons for the choice of the Unified Modeling Language instead of the use of proprietary modeling techniques. The idea followed by UWE to adhere to standards is not limited to UML. UWE also uses XMI as a model exchange format (in the hopes of future tool interoperability enabled by a truly portable XMI), MOF for meta-modeling, the model-driven principles given by OMG's Model-Driven Architecture (MDA) approach, the transformation language QVT, and XML. UWE is continuously adapting, on the one hand, to new features of Web systems, such as more transaction-based, personalized, context-dependent, and asynchronous applications. On the other hand, UWE evolves to incorporate the state of the art of software engineering techniques, such as aspect-oriented modeling, integration of model checking using Hugo/RT (Knapp et al., 2002; www.pst.ifi.lmu.de/projekte/hugo), and new model transformation languages to improve design quality. The remainder of this chapter is structured as follows: The features distinguishing UWE's development process, visual notation, and tool support are briefly outlined below. UWE's modeling techniques are discussed step by step in Section 7.2 by means of the online movie data-base case study. The UWE extensions of the UML meta-model are outlined in Section 7.3. UWE's model-driven process and, in particular, the model transformations integrated into the process are described in Section 7.4. The CASE tool ArgoUWE, which supports the UWE notation and method, is described in Section 7.5. Finally, we give an outlook on future steps in the development of UWE.