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International Journal of Computer Science & Information Technology (IJCSIT) Vol 3, No 4, August 2011 MDA-BASED ATL TRANSFORMATION TO GENERATE MVC 2 WEB MODELS M'hamed Rahmouni1 and Samir Mbarki1 1Departement of Computer Science, Faculty of Science, Ibn Tofail University, BP 133, Morocco md.rahmouni@yahoo.fr mbarkisamir@hotmail.com ABSTRACT Development and maintenance of Web application is still a complex and error-prone process. We need integrated techniques and tool support for automated generation of Web systems and a ready prescription for easy maintenance. The MDA approach proposes an architecture taking into account the development and maintenance of large and complex software. In this paper, we apply MDA approach for generating PSM from UML design to MVC 2Web implementation. That is why we have developed two meta-models handling UML class diagrams and MVC 2 Web applications, then we have to set up transformation rules. These last are expressed in ATL language. To specify the transformation rules (especially CRUD methods) we used a UML profiles. To clearly illustrate the result generated by this transformation, we converted the XMI file generated in an EMF (Eclipse Modeling Framework) model. KEYWORDS MDA, Meta-models, Transformation rules, ATL, MVC 2 Web, UML Profiles 1. INTRODUCTION Nowadays, it is well recognized that model transformation is at the heart of model driven architecture (MDA) approaches and represents as a consequence one of the most important operation in MDA. The goal of this transformation is to come to a technical solution on a chosen platform from independent business models of any platform [1]. Indeed, the MDA is a new discipline of software engineering that has emerged to ensure the development of productive models [2][3]. MDA brings an important change in the conception of applications taking in account the durability of savoir-faire and of gains of productivity, and taking profits of platforms advantages without suffering of secondary effects[4][5]. Hence, a considerable number of tools supporting the MDA has been developed. On the other hand, many implementations of the MVC 2 pattern, in the field of Web applications, have been carried out. At this level, we cite the following frameworks: Struts [6], Spring MVC [7], php.MVC [8], Zend [9], PureMVC [10]. Among these frameworks, Struts has attained maturity and so has gained the confidence of developers. This paper presents a tool that transforms a class diagram, which contains CRUD operations, to a model target (especially struts). The result of this transformation is an XMI file that will be subsequently used as a model to generate the source code of a MVC2 Web application. This tool allows to retrieve, delete, update and create the different objects of the information system. The emphasis is placed on the associations between classes. The process of transformation which consists in producing the XMI file is realized using the ATL language (Atlas Transformation Language) [11][12][13]. The remainder of this paper is organized as follows: Section 2 introduces MDA architecture, languages of metamodeling and transformation. Section 3 is devoted to the UML meta-model DOI : 10.5121/ijcsit.2011.3405 57

International Journal of Computer Science & Information Technology (IJCSIT) Vol 3, No 4, August 2011 and MVC 2 Web meta-model. Section 4 presents the specification of CRUD operations by UML profiles. Section 5 describes the process of development, implementation and execution of transformation rules. Section 6 is dedicated to the related work. Finally, section 7 concludes the work and gives hints about future work. 2. MODEL-DRIVEN ARCHITECTURE (MDA): The architecture of MDA is divided into four layers. In the first layer, there are the standard UML (Unified Modeling Language), MOF (Meta-Object Facility) and CWM (Common Warehouse Meta-model). In the next layer, there is the standard XMI (XML Metadata Interchange) which facilitates the exchange of models and their storage. The third layer contains the services that manage events, security and transactions. The final layer provides frameworks adaptable to different types of applications (Finance, Telecom, Transportation, Medical, etc..) [2][3]. The key principle of MDA is the use of models at different phases of application development. Specifically, MDA supports the development of requirements model (CIM), analysis and design (PIM) and code (PSM). The major objective of MDA is to develop perennial models, independent of the technical details of implementation to enable the automatic generation of the entire application code and obtain a significant gain in productivity. In the remainder of this section, we present the main artifacts of the engineering of models, languages expressing the meta-models and the transformation of models: MOF (Meta Object Facility) has been adopted by the OMG in 1997. The MOF specification defines an abstract language and a framework for the specification, construction and management of the generic meta-models. In addition, MOF defines a platform for the implementation of models described by the meta-models [14]. ECORE is a meta-modeling language that is part of EMF (Eclipse Modeling Framework) and is the result of ETP project efforts (Eclipse Tools Project). EMF is a modeling framework and code generation to support the creation of tools and model driven applications. ECORE defines key elements as: EnamedElement, eClassifier, ETypedElement, EPackage, eClass, EDataType, EAttribute, eReference, EOperation. The model transformation plays a role in the model driven engineering. To this end, several studies have been conducted to define transformation languages effectively and to ensure traceability between the different types of MDA models. ATL (Atlas Transformation Language) is a model transformation language developed in the framework of the ATLAS project [12]. ATL is developed by the team of Jean Bézivin at LINA in Nantes. It is part of the Eclipse M2M (Model-to-Model). conforms to transformation MOF MMa ATL MMb mma2mmb.atl Ma Mb Figure 1. Operational framework of ATL. 58

International Journal of Computer Science & Information Technology (IJCSIT) Vol 3, No 4, August 2011 3. UML AND MVC 2 WEB META-MODELS: According to the diagram shown in Figure 1, we present in this section the different meta- classes that constitute the PIM and PSM meta-models. Figure 2 illustrates the source meta- model that is a simplified representation of a UML class diagram. UMLPackage corresponds to the concept of UML package, this meta-class is related to the Classifier meta-class. This represents both the concept of UML class and the concept of data type. The Property meta-class expresses the concept of properties of an UML class or references to other classes (uni and bidirectional associations). Figure 3 corresponds to the PSM meta-model. In this meta-model, we show more interest in the tier controller. The ActionMapping meta-class contains the information deployment for a particular Action class. The ActionForm meta-class is a Bean encapsulating the parameters of a form from the view part. The execute() method of Action class performs its processing and then calls the findforward() method on the mapping object . The return value is an object of an ActionForward type. The Action meta-class represents the concept of secondary controller. The Action classes contain the specific processing of the application. Consequently, they must be related to business classes. The complete target meta- model is detailed in [15]. Figure 2.UML meta-model source. Figure 3.Struts meta-model. 59

International Journal of Computer Science & Information Technology (IJCSIT) Vol 3, No 4, August 2011 4. SPECIFYING CRUD OPERATIONS BY UML PROFILES: When the UML can not represent a system or application in a practical way, a UML profile can provide extra features to do [16][17]. A UML profile is an adaptation of UML to a particular area [2][18]. It consists of stereotypes, constraints and values marked [19]. A stereotype defines a subclass of one or more elements of the UML meta-model. This subclass has the same structure as its basic elements, but the stereotype specifies constraints and additional properties. In the next section we will specify the operations Create, Retrieve, Update and Delete (CRUD) by UML profiles to predict and specify the outcome of the ATL transformation. The operating algorithm of these operations is based on the principle and architecture of MVC2 Web: Struts [6]. Figure 4 describes this principle. Controller Figure 4. MVC 2 Web Architecture 4.1. RetrieveCi Operation The aim of the RetrieveCi operation is to display all Ci entities registered in the database already created. This operation is described as follows: Figure 5. Specifying RetrieveCi operation 4.2. The CreateCi Operation This operation aims at the creation or addition of a new Ci entity in the database. It is described below. 60

International Journal of Computer Science & Information Technology (IJCSIT) Vol 3, No 4, August 2011 Figure 6. Specifying the CreateCi operation. 2.3. UpdateCi Operation The Ci entity data recorded in the database may be incorrect or false, to correct or change it, we apply the UpdateCi operation detailed as follows by the UML profiles: Figure 7. Specifying CreateCi operation. <> Error Figure 7. Specifying the CreateCi operation 2.4. DeleteCi Operation The data recorded in the database and which are useless, must be removed. The DeleteCi operation was designed for this role: 61

International Journal of Computer Science & Information Technology (IJCSIT) Vol 3, No 4, August 2011 Figure 8. Specifying DeleteCi operation The specification of other CRUD operations that correspond to Cj and Ck classes will be the same way as that of the Ci class. 5. IMPLEMENTATION AND EXECUTION OF TRANSFORMATION RULES In this section, we present the transformation rules allowing to generate a MVC 2 web model from UML class diagram specified by UML profiles and the implementation of these rules then its results after the execution. In this article we consider only the operations CRUD that Create, Retrieve, Update and Delete, each generates an element of an ActionForm type. The Retrieve operation relating the root class does not generate an ActionForm. The "Create" and "Delete" operations that already performed in [20]. Before proceeding to the execution of the transformation rules, we first created ECORE models corresponding to our two source and target meta-models. In second step, we have implemented the rules of ATL transformation language. The result of XMI file, generated by this transformation, is converted to an EMF model. To validate our transformation rules, we applied more tests. The validation of these rules is also based on the specification of CRUD operations shown above. As an illustration, we consider the UML diagram composed by the classes Ci, Cj and Ck. We get the following XMI model. The target model contains all CRUD operations that: Create, Retrieve, Update and Delete. For the "Retrieve" operation, the Ci root class has no ActionForm. For the "Delete" operation, the input attribute of the "DeleteCiAction" action tag is "/RetrieveCi.jsp" because it is deleting a line from the list of its properties. Figure 9. Source Model UML 62

International Journal of Computer Science & Information Technology (IJCSIT) Vol 3, No 4, August 2011 5.1. Rule That Generates the JSP Pages Figure 10. Rule That Generates the JSP Pages Figure 11. The Generated result: Package of JSP pages Figure 12. Equivalent result in EMF: Package of JSP Pages 63

International Journal of Computer Science & Information Technology (IJCSIT) Vol 3, No 4, August 2011 5.2. Rule that Generates the Action Classes Figure 13. Rule that Generates the Action Classes 64

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