Uml-Based Web Engineering - An Approach Based on Standards

7.1 Overview UML-based Web Engineering (UWE, www.pst.ifi.lmu.de/ projekte/uwe) came up by the end of the nineties (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 The aim, which is still pursued, was to use a common language or at least to define metamodel-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 approaches of Booch, OOSE and OMT seemed to be a promising approach for system modeling. Since the early integration efforts, the 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. 144 Both the acceptance of the UML as a standard in the development of software systems and the flexibility provided by the extension mechanisms 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 uses also XMI as model exchange format (in the hope of future tool interoperability enabled by a truly portable XMI), MOF for metamodeling, 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 Sect. 7.2 by means of a simple online movie database case study. The UWE extensions of the UML metamodel are outlined in Sect. 7.3. UWE's model-driven …