Model – Driven Content Management in Web Applications

Model – Driven Content Management in Web Applications

Ms. Amruta Pawar

Department of Computer Science & Engineering Solapur University, Solapur,

Solapur,India.

Dr. R. B. Kulkarni,

Department of Computer Science & Engineering Solapur University, Solapur,

Solapur,India.

AbstractIt is a complex and error-prone process to develop and maintain Web Applications. We need integrated techniques and tool support for automated generation of Web systems and a ready prescription for easy maintenance. The MDA (Model Driven Architecture) approach proposes an idea taking into account the development and maintenance of large and complex software. In this paper, we propose to apply MDA approach for generating PSM (Platform Independent Model), MVC 2 Web implementation from UML design. For this it is needful to develop two meta-models handling UML class diagrams and MVC 2 Web applications separately and use transformation rules. These last can be expressed in ATL (Atlas Transformation Language) language.

Keywords MDA, Meta-models, Transformation rules, ATL, MVC 2 Web, UML Profiles.

1. INTRODUCTION

   Model Driven methodology helps assure modularized existence of a web application. A Web Application is a software program that is stored on a remote server and delivered to the end user over the Internet, through a web browser. It is an application that uses web browser as a client and is made up of logical units called tiers namely; presentation, application and storage. Web browser is the first tier, dynamic web content determines middle tier and database or storage is the third tier.

   With increased complexity of web applications it becomes necessary to provide quick and easy access to the desired content. If the entire application is modularized and modeled according to the functionalities the dynamical feature of it can be preserved. Various technical areas like software engineering, hypertext engineering, data design, graphic design and presentation modeling merge in to achieve the need of complex web applications.

   Model-View-controller (MVC) is a software architecture that helps separate information and its representation from its resulting interaction with the user. Thus the primary task of the project to which this design document belongs is converting conventional web application into MVC architecture.Web applications today are using this concept for reusability and modularity. Model, view and controller are the three aspects of the MVC architecture that deal with data definition, navigation, presentation and so on. Together they are responsible to generate the final code for the user access.

   Atlas Transformation Language, an Atlas INRIA & LINA research group product is a model transformation language specified both as metamodel and as a textual concrete syntax. It is a declarative style of transformation generally concerning simple mappings whereas complex mappings are handled by imperative constructs. ATL programs contain rules that define how target models elements are obtained from source model elements.

2. IDEA OF PAPER

   1. Problem Statement

      The paper proposes an idea of implementing model- driven methodology to transforms a class diagram to a target model which takes an XMI format. This XMI file can be subsequently used to generate the source code of a MVC based web application. The idea is to reuse common aspects across different applications as rules and reduce repetitive tasks.

   2. Objective and Scope

   Model driven methodology is to be used to transform a class diagram to a target model. This is going to ease the task of repetitive design along with the task of testing the application. The idea intends to ease the testing and maintenance of an application. Making it model driven, this project aims at reliving the task of repetitive programming and tedious testing procedure. The idea is to begin with UML representation of classes and then using the concept of Atlas Transformation Language, generate a target model and use it to develop source code of MVC web application.

3. LITERATURE REVIEW

The evolution of web applications is marked by Web Engineering methodologies which help develop them systematically merging various areas of technology like, software engineering, human computer interaction, graphic design etc., [1]. The impact of purpose on user preferences is very large. The content orientation as well attracts users and needs a lot of work behind [2].

Model-driven approach imports a number of models into real web application. The method separates various aspects of web design i.e., process view, content view, navigation view and presentation view [3]. This approach has been

saving a lot of repetitive work. An example approach is MVC architecture.

Using MVC architecture allows the creation of large and complex, but flexible and easy to maintain web applications. These applications are easy to develop and maintain because the user interface code is separate from the database access code. This makes the code much easier to write, test, and debug. Model driven architecture is higher version of MVC itself. With regards to web application development, study so far has been accompanied with MVC architecture. Model driven method may prove to be a better approach towards the same because of all the abstract models used. These help in separating varied tasks. [7].

A study of model driven architecture with MVC presents a work of model-driven approach to developing web applications based on Ubiquitous Web Application conceptual design methodology and MVC architecture. The UWA design framework along with its methodology and models is particularly suited for designing web applications which are intended to be accessible by different user types in different usage contexts and with different goals [11].

The MVC design pattern divides a web application into three parts; handling the user-interactions, computations and output display. This separation favors architectural reusability to great extent. The designers need to decide which of the components of the architecture are to be partitioned between the server and client. For a designer is very difficult to incorporate future changes in policies related to partitioning in application. A solution to this problem is to duplicate the Model and controller components at both server and client respectively. This too may add problems like delay in fetching data, security and scalability issues, etc. Hence to overcome this drawback, a new architecture SPIM has been proposed that deals with the partitioning problem in an alternative way. Third party mash up technique is applied to client views hence reducing the task of the server or storage. This approach shows tremendous improvements in performance when compared with a similar architecture. Hence it can also be considered to be an improvisation with MVC. Certainly model driven methodology can reduce the task further by simply modularizing the application itself. In literature the problem of automatic display layout is applied for fields like computation of graph based diagrams, layout of graphs, document presentation and so on [5] and [8]. The problem is realized by means of constraint specification or a set of rules, fixed or customizable.

Research presents a solution to web based system evolution which consists of components like understanding, representation and evolvable framework development. Everything here thence can be modeled. Displace of the content of applications is made easy because of model- driven approach It also helps compose and reuse components. But development and maintenance of Web application is still a complex and error-prone process for which we need integrated techniques and tool support for automated generation of Web systems and methods for easy maintenance. The MDA approach proposes an architecture taking into account the development and maintenance of large and complex software. Model transformation then

becomes a necessity. Hence a model transformation language like ATL is widely used [14] and [15]. ATL i.e. Atlas Transformation Language helps overcome the gap between two distinct models. In model engineering all handled items are to be considered as models. The model transformation itself therefore has to be defined as a model and this transformation model has to conform to a transformation metamodel that defines the model transformation semantics. As other metamodels, the transformation metamodel has, in turn, to conform to the considered metamodel. The entire procedure gives you a target model from which further automation depends.

The quality of any web application depends on the GUI, the content, different entity structure wealth and challenges associated with them are navigability, visual presentation etc. This takes time to achieve. Idea has thus emerged to invest in reducing time required for doing repetitive tasks like create, remove, update and display of the different objects. This work is very useful for users called to manipulate some information linked to each other in an arborescent structure where the display of information depends on another (display, as part of a web application, employees of a service, of a division, of a direction, etc.). Therefore, the idea is to apply MDA approach for generating PSM form UML class diagram. This can take form of an MVC web application. We can start with UML class diagram itself which has information about its attributes and operations. The UML class diagram is the source model. Target model is MVC. The transformation is to be carried out by using ATL rules. Both source and target meta models are created. Transformation by ATL results in an XMI file which can be further used to generate MVC implementation code. Any application requires some repetitive, non-changing code for implementation. This idea helps for the provision of the same. It can greatly reduce development time.

IV PROJECT DETAILS

1. BASIC ARCHITCTURE

   Fig. 1. Basic Architecture

   The figure 1 above is the basic architecture of the proposed system. The idea is to begin with a platform independent model, use ATL and convert it later into a platform specific model thus generating implementation code.

2. TECHNOLOGY

   • A conventional web application is studied to determine its functional differences. These different functional models actually depict functional independency of the entire web application.

   • Business logic, static data and navigational information individually form MVC modules.

   • The goal is to achieve easy code generation of the business logic; entities that are not much modified.

   • ATL is used to convert source model to a target model using rules.The XMI file generated further helps develop code of the application.

3. MODEL VIEW CONTROL ARCHITECTURE

   MVC (Model-View-Controller) is a software design pattern for developing web applications. This pattern consists of three parts namely, Model, View and Controller. Model is at lowest level dealing with business logic or data. View concerns user accessible part. Controller acts as the interface between the above two. This is accomplished as follows:

   • Various static views and UI elements shown to the user be identified as views

   • Identify the navigational pattern present in views which let the views transition from one to another as controller

   • The final server side code, handling Business Logic will be identified as model

     In this way a conventional web application is converted into an MVC patterned web application.

4. MODEL DRIVEN APPROACH

   Model-driven engineering approach defines web development as set of models and their inter transformations. Three models related to web development are data model, hypertext model and presentation model.

   • Data Model: The data model consists of the data objects, their attributes, methods and inters relationships as described by ER diagrams. Data model relates to the model part of MVC i.e., business logic and server side code from conventional web applications becomes data model in MDA.

   • Hypertext Model: The hypertext model consists of the pages that comprise the web application, along with user navigation depicted in terms of links. Hypertext model may be considered as a site view which a particular set of users can access. It takes care of various data units and their interrelations that form the actual content. Hypertext model relates to controller part of MVC i.e., navigation pattern and view transition logic from conventional web application becomes Hypertext Model in MDA.

   • Presentation Model: Presentation model renders the logical view of the hypertext for a particular platform. Presentation model relates to view part of the MVC i.e., static views and UI elements that are shown to the user becomes Presentation Model in MDA.

5. ATLAS TRANSFORMATION LANGUAGE

   Atlas transformation language is a model transformation language released under the terms of the Eclipse Public License and Eclipse component used inside of the Eclipse Modelling Project (EMP). It is developed by OBEO and INRIA.

   Fig. 2. ATL Architecture

   Here Ma is the source model which conforms to source meta model MMa. Mb is the target model which conforms to meta model MMb. MMa2MMb.atl is the ATL transformation file that contains rules which help transform Ma to Mb using meta models. This file is also a model and so it conforms to ATL meta model. All meta models conform to MOF (Meta Object Facility) which framework for specification, construction and management of meta models. ECORE is a meta-modelling language that is part of EMF (Eclipse Modelling Framework) and is the result of ETP project efforts (Eclipse Tools Project). EMF is a modelling framework and code generation to support the creation of tools and model driven applications.

   • UML And MVC 2 Web Meta-Models:

   According to the diagram shown in Figure 2, the different metaclasses that constitute the PIM and PSM meta- models. Figure 3 illustrates the source metamodel that is a simplified representation of a UML class diagram. UML Package 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. Figure 4 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.

   Fig. 3. UML meta-model, source.

   Fig. 4. Struts meta-model, target

   V. CONCLUSION

   Model driven approach and model transformation technology can help to achieve a more automated process for developing Web applications. We can generate ingredients of a web application based on UML class diagrams. These ingredients are to form model, view and controller entities of an MVC web application The XMI file which can be obtained as a result of ATL transformation can be used to generate necessary partial code of a target web application. The developers of web applications can use such tools and reduce implementation time to a great extent. Using model transformation language like ATL we can transform PIM to PSM which is platform specific model. Technology can avail us with the possibility of generating Java classes as snippets of an entire application thus reducing the task of a developer.

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