UML to XML-Schema Transformation: a Case Study in Managing Alternative Model Transformations in MDA

In a Model Driven Architecture (MDA) software development process, models are\ud repeatedly transformed to other models in order to finally achieve a set of models with enough details to implement a system. Generally, there are multiple ways to transform one model into another model. Alternative target models differ in their quality properties and the selection of a particular model is determined on the basis of specific requirements. Software engineers must be able to identify, compare and select the appropriate transformations within the given set of requirements. The current transformation languages used for describing and executing model transformations only provide means to specify the transformations but do not help to identify and select from the alternative transformations. In this paper we propose a process and a set of techniques for constructing a transformation space for a given transformation problem. The process uses a source model, its meta-model and the meta-model of the target as input and generates a transformation space. Every element in that space represents a transformation that produces a result that is an instance of the target meta-model. The requirements that must be fulfilled by the result are captured and represented in a quality model. We explain our approach using an illustrative example for transforming a platform independent model expressed in UML into platform specific models that represent XML schemas. A particular quality model of extensibility is presented in the paper

Modeling views in the layered view model for XML using UML

In data engineering, view formalisms are used to provide flexibility to users and user applications by allowing them to extract and elaborate data from the stored data sources. Conversely, since the introduction of Extensible Markup Language (XML), it is fast emerging as the dominant standard for storing, describing, and interchanging data among various web and heterogeneous data sources. In combination with XML Schema, XML provides rich facilities for defining and constraining user-defined data semantics and properties, a feature that is unique to XML. In this context, it is interesting to investigate traditional database features, such as view models and view design techniques for XML. However, traditional view formalisms are strongly coupled to the data language and its syntax, thus it proves to be a difficult task to support views in the case of semi-structured data models. Therefore, in this paper we propose a Layered View Model (LVM) for XML with conceptual and schemata extensions. Here our work is three-fold; first we propose an approach to separate the implementation and conceptual aspects of the views that provides a clear separation of concerns, thus, allowing analysis and design of views to be separated from their implementation. Secondly, we define representations to express and construct these views at the conceptual level. Thirdly, we define a view transformation methodology for XML views in the LVM, which carries out automated transformation to a view schema and a view query expression in an appropriate query language. Also, to validate and apply the LVM concepts, methods and transformations developed, we propose a view-driven application development framework with the flexibility to develop web and database applications for XML, at varying levels of abstraction

Subjects, Models, Languages, Transformations

Discussions about model-driven approaches tend to be hampered by terminological confusion. This is at least partially caused by a lack of formal precision in defining the basic concepts, including that of "model" and "thing being modelled" - which we call subject in this paper. We propose a minimal criterion that a model should fulfill: essentially, it should come equipped with a clear and unambiguous membership test; in other words, a notion of which subjects it models. We then go on to discuss a certain class of models of models that we call languages, which apart from defining their own membership test also determine membership of their members. Finally, we introduce transformations on each of these layers: a subject transformation is essentially a pair of subjects, a model transformation is both a pair of models and a model of pairs (namely, subject transformations), and a language transformation is both a pair of languages and a language of model transformations. We argue that our framework has the benefits of formal precision (there can be no doubt about whether something satifies our criteria for being a model, a language or a transformation) and minimality (it is hard to imagine a case of modelling or transformation not having the characterstics that we propose)

An OCL-Based approach to derive constraint test cases for database applications

The development of database applications in most CASE tools has been insufficient because most of these tools do not provide the software necessary to validate these appli-cations. Validation means ensuring whether a given application fulfils the user require-ments. We suggest validation of database applications by using the functional testing technique, which is a fundamental black-box testing technique for checking the software without being concerned about its implementation and structure. Our main contribu-tion to this work is in providing a MDA approach for deriving testing software from the OCL specification of the integrity constraints. This testing software is used to validate the database applications, which are used to enforce these constraints. The generated testing software includes three components: validation queries, test cases and initial data inserted before the testing process. Our approach is implemented as an add-in tool in Rational Rose called OCL2TestSW.This work has been partially supported by the project Thuban: Natural Interaction Platform for Virtual Attending in Real Environments (TIN2008-02711), and also by the Spanish research projects: MA2VICMR: Improving the access, analysis and visibility of the multilingual and multimedia information in web for the Region of Madrid (S2009/TIC-1542).Publicad

A MDA-BASED DEVELOPMENT APPROACH FOR 3-TIERS APPLICATIONS

This study presents a MDA transformation approach for 3-tiers applications. CIM-to-PIM and PIM-to-PSM transformation rules are developed. This approach is demonstrated using an on-line bookshop application. With this approach, the weak link of MDA, CIM-to-PIM transformation, can be tackled, and 3-tiers applications can more systematically be analysed, designed, and generated and, thereby, increase system development productivity