外文翻译--基于Java技术的Web应用设计模型的比较研究

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1、3690 单词， 19100 英文字符， 5763 汉字 出处： Kurniawan B, Xue J. A Comparative Study of Web Application Design Models Using the Java Technologies.J. Lecture Notes in Computer Science, 2004, 3007:711-721. 外文文献资料 A Comparative Study of Web Application Design Models Using the Java Technologies Kurniawan B, Xue J A

2、bstract. The Servlet technology has been the most widely used technology for building scalable Web applications. In the events, there are four design models for developing Web applications using the Java technologies: Model 1, Model2, Struts, and JavaServer Faces (JSF). Model 1 employs a series of J

3、SP pages； Model 2 adopts the Model-View-Controller pattern； Struts is a framework employing the Model 2 design model； and JSF is a new technology that supports ready-to-use components for rapid Web application development. Model 1 is not recommended for medium-sized and large applications as it intr

4、oduces maintenance nightmare. This paper compares and evaluates the ease of application development and the performance of the three design models (Model 2, Struts, and JSF) by building three versions of an online store application using each of the three design models, respectively. 1 Introduction

5、Today, Web applications are the most common applications for presenting dynamic contents. There are a number of technologies for building Web applications, the most popular of which is the Servlet technology . This technology gains its popularity from its superiority over other technologies such as

6、CGI and PHP .Servlets are cumbersome to develop, however, because sending HTML tags requires the programmer to compose them into a String object and send this object to the browser. Also, a minor change to the output requires the servlet to be recompiled. To address this issue, Sun Microsystems inve

7、nted JavaServer Pages (JSP) . JSP allows HTML tags to be intertwined with Java code and each page is translated into a servlet. A JSP page is a servlet. However, compilation occurs automatically when the page is first requested. As a result, changing the output does not need recompilation. In additi

8、on, JSP enables the separation of presentation from the business logic through the use of JavaBeans and custom tag libraries. The norm now in developing Javabased Web applications is to use servlets along with JavaServer Pages. In the later development, there are a number of design models for buildi

9、ng servlet/JSP applications: Model 1, Model 2, Struts , and JSF . Model 1 and Model 2 were first mentioned in the early specifications of JSP. Model 1 strictly uses JSP pages, with no servlets, and Model 2 uses the combination of both servlets and JSP pages. The terms of Model 1 and Model 2 have bee

10、n used ever since. Model 1 is suitable for prototypes and very small applications, and Model 2 is the recommended design model for medium sized and large applications. As Model 2 gained more acceptances in the industry, an open source initiative to build the Struts Framework was initiated. Struts pe

11、rfects Model 2 by providing the controller part of the Model-View-Controller of Model 2. In addition, Struts provides better page navigation management and several custom tag libraries for more rapid development. Despite its steep learning curve and the fact that it was never defined in any specific

12、ation, Struts has been gaining popularity as the alternative to Model 2. JavaServer Faces is built under the Java Community Process under JSR-127.Sun Microsystems proposed this technology in the hope that JSF will be the ultimate model for building Java Web applications. The most important feature o

13、f JSF is the availability of ready-to-use components such as extensible UI components, easy page navigation, input validators, data converters and JavaBeans management. The problem facing servlet/JSP programmers are to choose the most appropriate design model. Clearly, JSF provides a better solution

14、 in regard to development time. However, some people are not sanguine to adopt this technology for fear of performance penalty due to the overhead of the JSF implementation. We build three versions of an online store application named BuyDirect using Model 2, Struts and JSF. The parameters compared

15、are the number of lines of code, the number of classes, and the performance measurement results. We investigate which of the design models allows the most rapid development process. We evaluate the performances of the applications built upon these models. We provide some suggestions to perfect the e

16、xisting design models to make development more rapid. The rest of the paper is organised as follows. Section 2 discusses the issues in Web development. Section 3 explains how the three design models address these development issues. Section 4 provides the details of the hardware and software used in

17、 these experiments. Section 5 presents the experiment results and analysis. Section 6 reviews the related work. Section 7 concludes by offering some suggestions to improve the existing design models. 2 Java Web Development Issues All Java Web development uses the Servlet technology as the underlying

18、 technology. As such, all Java Web applications have certain issues that need to be addressed: User Interface. The user interface is what the client browser renders as HTML tags. Any server-side component used in the application must be encoded into the corresponding HTML elements. Besides for displ

19、aying the content and data, the user interface is also responsible in receiving input from the user. Input Validation. User input needs to be validated. There are two types of input validation, server-side and client-side. As the name implies, the server-side input validation is performed on the ser

20、ver after the input reaches the server. Client-side input validation is done on the browser, usually by using JavaScript or other scripting languages. The advantages of using client-side input validation are prompt response and reducing the server workload. The server-side input validation should al

21、ways be performed regardless the presence of client-side validation because there is no guarantee the user browsers scripting feature is being on and malicious users can easily work around client-side validation. Model Objects. Model objects in Java-based Web applications are in the forms of JavaBeans. Model objects make up the Model part of the MVC based design