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1、精品文档，仅供学习与交流，如有侵权请联系网站删除 计算机专业英语大作业Patterns Instruction in Software EngineeringAbstract:The paper deals with a training system with a client-server architecture created forstudents who are learning to design and implement object-oriented software systemswith reusable components, and also targeting t
2、hose users who wish becomeaccustomed with (or improve their skills related to) software design. The paper brieflypresents the design patterns which are to be found in the software library, as well asthe manner of applying them. The user of such a system has five types of patterns athis/her disposal
3、(Factory Method, Builder, Command, Mediator, Observer), out ofwhich will be able to chose one/more than one, depending on the requirements of thesystem proposed for design.1.IntroductionMotto: “The software design patterns help you learn more from other peoples successes than from your own failures”
4、 Mark Johnson .A software system is a dynamic entity that undergoes multiple changes during its life-cycle, under the influence of factors such as: new user requirements, adding new functionalities, environment adjustment, etc. Therefore, apart from fulfilling those functions which it was designed t
5、o fulfill, a software application must be easily changeable, with some of its modules eventually re-used. Having this goal, the application must fulfill certain requirements regarding robustness, mobility, flexibility, scalability, etc. The software design principles are regarded as ways of obtainin
6、g the right and re-usable design. By applying abstractization and OOP languages polymorphic techniques, the open-shut principle and the substitution principle (Liskov) upon classes of problems, common solutions were reached solutions which make up the so-called design patterns. The software patterns
7、 facilitate re-using design and architecture. If the design and/or architecture of a system were built with design patterns (techniques which have proven efficient), then they will be more accessible and easier to understand by those software developers who build new systems based on old design. The
8、 patterns help the software specialist chose that design that makes the system re-usable. In software engineering, “design pattern” (DP) means a solution applicable to a certain type of problems. A design pattern is a description model of how a problem should be solved. A pattern cannot be directly
9、transformed in source code. The purpose of design patterns is to enable a “good” object-oriented design, and more than that to make it reusable (which is more important than reusing the code, regardless of the fact that reusing the design often implies reusing the code). The quality of software desi
10、gn is proportional to the experience and previous knowledge of the one performing it. An expert applies solutions previously used and proven efficient for similar problems. When the expert finds a solution considered acceptable, he/she uses it again. Design patterns solve specific design problems, m
11、aking the OO more flexible, elegant and reusable. DP help beginners with software design, proposing patterns based on previous experience. A user who is familiar with the DP-s can apply them instantly in order to solve specific problems, without having to rediscover them. By using the software desig
12、n patterns while designing an object-oriented architecture, one is guaranteed to obtain system compliance to software engineering principles, while also preserving the qualities of “good design”: reusable, flexible, robust .2. Design PatternsDepending on the DP purpose, the authors of GoF 4 proposed
13、 three main categories of patterns: creational patterns, structural patterns and behavioral patterns. These are the most well-known DP, but not the only ones. Other types of patterns emerged more or less popular as well as variations of the GoF patterns.A pattern has four essential components:1. Nam
14、e: the name of the DP must describe in a few words a design pattern problem, its solutions and the solutions effects.2. Problem: describes the situations when the pattern is applicable, explaining theproblem as well as its context.3. Solution: describes the components of the design, the relationship
15、s between them, the responsibilities of each component and the way they interact. The solution does not describe a specific design for a certain situation or a correct implementation, because a pattern has a general character, referring to a plethora of contexts. The DP presents an abstract descript
16、ion of a problem and a general arrangement of the components (classes and objects) that solve the described problem.4. Effects: refer to the results of applying the pattern, which are very important when we evaluate the alternatives and we estimate the costs and benefits of applying the pattern. The
17、 effects of a pattern are also to be perceived in the flexibility, extensibility and portability of a system. DP identifies the classes and instances which participate, their role, collaboration and responsibility sharing between them.The design patterns that the user of the proposed system has at h
18、and are: Factory Method and Builder (from the Creational Patterns category), Command, Mediator and Observer, (from the Behavioral Patterns category).3. The Architecture of the SystemThe platform is designed as a distributed application, providing the option of distancelearning/tutoring by means of a
19、 computer network or the Internet. The application can be classified as having “three - tier architecture, the Client part being represented by the configuration module and the tutoring material presentation module. The user connects to the system by means of a Login module, monitored by an Administ
20、rator agent (CerberusAgent). After authentication the user may have access to a configuring instrument (if the user connected to the system is the tutor) or to the user interface by means of which the learning material will be presented (if the user is a student). This part of the application will b
21、e monitored by an interface agent (InterfaceAgent).The application server contains the agent platform that monitors the student activity, and a web server responsible for delivering the learning material to the user interface (Apache Tomcat).The third level consists of a xml database (Apache Xindice
22、), which stores information about the structure of the course, student models, etc. The MTS training system is designed for students which learn to design and implement object-oriented software systems, with re-usable components, but also for those users who wish to become familiar with (or improve)
23、 software design. We present the approach of a multi-agent intelligent platform for tutoring student which provides a Student Model. The “modeling student process” used the overlay architecture (common for many tutoring systems) combined with the Bayesian Theory of Probability . The systems tasks ar
24、e distributed among the intelligent agents (software agents), each having clearly specified individual roles as following: administrator (Cerberus Agent); interface (InterfaceAgent); tutor (Tutor Agent); student (Student Agent). Moreover, the system has “three-tier” architecture and was implemented
25、in Java language. We may well imagine software agents attached to every application or tutoring environment, each having an explicit representation of the users objectives, of their plans and resources. These agents communicate and negotiate with each other in order to fulfill their individual or gr
26、oup objectives. The multi-agent tutoring system (MTS) was designed and implemented within the Computer Science Department, in which research focused upon “modeling” the student with a view to identifying the most suitable methods and tutoring strategies by taking into account individual knowledge an
27、d abilities.The user of this kind of system has all five types of previously described patterns at his/her disposal (Factory Method, Builder, Command, Mediator, Observer), out of which will be able to use one or more, depending on the requirements of the system that needs to be designed.Depending on
28、 the needs of the user that must fulfill the requirements of the system, one selects from Tutor Agent the design patterns best suited for those functions. The patterns help build the menus of the application and the user interface. Then the database is built, as the user has permanent access to an e
29、xample of application as similar as possible to the one which needs to be carried out. In order to develop an application, the student must know the Java programming language, must be familiar with MySql data servers and must be able to use the Eclipse platform. The Eclipse platform is an open sourc
30、e framework from IBM which aims to provide a variety of basic services for software developers 6.4. ConclusionsThe system wishes to be a useful working instrument for software application development training, for both students and other types of users. A design pattern together with an example of u
31、sing that pattern may become a way of working in software design. Moreover, in this case applying design patterns therefore design principles - in carrying out an object-oriented application results into a reusable design and reusable modules / components.Also, the resulting code enjoys more robustn
32、ess and flexibility, these two characteristics being essential for developing new modules that would add new functionalities and operations to the application; the design/code of the application is open to extension and closed for changes, according to OCP.Another important aspect relates to the mai
33、ntenance activities which the designedapplication will undergo along its life-cycle: they will more cost effective, as no change will disseminate through the entire system, the application code being built so that it isolates the volatile classes (according to the principle of reversing dependencies
34、), the dependencies being in the way”details depend upon abstractization” and not the other way around. The software patterns ensure compliance to design principles, as they contribute to obtaining a steady and efficient system, and they provide design discipline for students. Last but not least, us
35、ing such a system in software engineering learning makes the process much more attractive and efficient. The design patterns approach in software engineering training fits thepedagogical Schemas Theory (created by Bartlett at the beginning of the 20th century) . A brief representation of the particu
36、lar knowledge of the training domain can help the trainee to easier absorb the new information, while the organization and structuring of the knowledge as patterns will guide him/her in finding (remembering) the necessary information in a certain context. We believe that within such an approach one
37、can create a training ontology from Software Engineering.软件工程模式教学摘要：本页处理一个C/S架构的训练系统，为学习设计和实施一个面向对象的用可重用组件的软件系统的学生而设计，也将目标瞄准那些用户谁希望成为（或提高他们的相关技能）软件设计习惯。 本文简要提出的设计模式，将被发现的软件库中，以及运用的方式。 这样一个系统的用户有五种类型的模式，在他/她的处置（工厂方法，生成器，命令，调解员，观察员），因为他们能够能够选择一个/一个以上，根据要求的系统的设计提出。1.介绍座右铭 :软件设计模式，帮助你从别人的成功中比从自己的失败中学到的更
38、多。Mark Johnson 软件系统是一个动态的实体，在其生命周期中经历了多次更改，的影响下的因素，例如：新的用户需求，增加新的功能，环境调整等，因此，它是除了履行这些职能设计，以满足必须的软件应用程序是很容易改变的，与一些模块最终重新使用。 有了这个目标，应用程序必须满足一定的要求健壮性，流动性，灵活性，可扩展性，软件设计原则视为获得的权利和可重复使用的设计方法。 通过施加抽象化和OOP语言多态技术，开闭原则，替代原则(Liskov)类的问题时，常见的解决方案达成了-解决方案组成了所谓的设计模式。 软件模式便于再利用的设计和架构。 如果一个系统的设计和/或体系结构设计模式构建（这已被证明是
39、高效的技术），那么他们就会更方便和更容易了解这些软件开发商建立新的系统，基于旧的设计。 该模式帮助软件专家选择，设计，使系统可重复使用的。 在软件工程，“设计模式”（DP, Design Pattern）表示的解决方案适用于特定类型的的问题。 设计模式是应解决的一个问题是如何描述/型号。 一个模式不能直接在源代码转化。设计模式的目的是使能以及超过一个“好”面向对象的设计，使可重复使用的（这是更重要的重复使用的代码，而不管事实上，重用的设计往往意味着重用代码）。 软件设计质量正比于先前的经验和知识，以及设计软件的人。 一位专家运用与以前使用过的方法和已经证明有效的解决类似问题的问题。 当专家发现
40、一个解决方案考虑到可以接受，他/她会再用一次。设计模式解决特定设计问题，使得面向对象更灵活，优雅和可重复使用的。 DP帮助初学者软件设计，根据以往的经验提出的模式。 一个熟悉DP-s的用户可以立即运用它以解决复杂问题，而无须重新发现它们。当设计面向对象架构时候通过设计软件模式，一个是保证获得系统符合软件工程原则，同时也保留了“好设计”的素质：可重复使用的，灵活的，健壮的。2.设计模式基于DP的目的，GoF的作者提出了3种主要的模式类型：创建型模式，结构模式和行为模式。 这些是最有名的DP，但不是唯一的。出现其他类型的模式（或多或少有点受欢迎）以及GoF模式的变化。一个模式有四个基本要素：1 名
41、称 ：DP的名称必须用几句话描述设计模式的问题，其解决方案和解决方案的效果。2 问题 ：描述模式是适用的情况下，解释的问题，以及它的上下文。3 解决方案 ：描述了部件的设计，它们之间的关系，每个组件和互动的方式，他们的职责。 该溶液不描述一个特定的设计某种情况或正确实施，因为图案具有共性，指过多的上下文。 DP提供了一个一个问题，一般布置的组件的抽象描述（类和对象），解决上述问题。4 效果：是指应用的模式，这是非常重要的结果，我们评估替代品和我们估计的成本和效益的应用模式。的图案的影响也被感知的灵活性，可扩展性和一个系统的可移植性。DP标识类和参与的情况下，它们的作用，协作和它们之间的责任分担
42、。的用户所提出的系统具有设计模式：工厂方法命令，调解员和观察员，（从生成器（从创建模式类别），行为模式类）。3.系统的体系结构该平台被设计成一个分布式应用程序提供的选项的距离学习/辅导通过计算机网络或互联网。该应用程序可以被归类为具有“三层”架构，客户端部分表示由配置模块和辅导材料上介绍模块。 该用户连接到系统通过一个登录模块，由管理员监控剂（CerberusAgent）。经过认证的用户可以访问配置工具（如果用户连接到系统的导师）或用户界面，通过该学习材料将存在（如果用户是一个学生）。 这部分的应用将是监控接口主体（InterfaceAgent）。应用程序服务器包含的代理平台，监控学生活动，并
43、负责到用户界面提供的学习材料的web服务器（Apache的Tomcat）中。第三个层次，由一个XML数据库（Apache的Xindice的），其中存储的信息的结构的过程中，学生模型，等等。MTS培训系统是专为学生学习设计和实施面向对象的软件系统，具有可重用的组件，同时也为这些用户谁希望成为熟悉软件设计（或改善）。 我们提出的方法多代理的智能辅导平台，为学生提供学生模型。 该“学生过程建模”使用覆盖架构（常见于许多辅导系统）结合贝叶斯概率理论。分布在系统的任务的智能代理软件代理，每个都具有个别的角色，明确规定以下内容：管理员接口（Cerberus代理）;（InterfaceAgent）;导师（导
44、师代理），学生（学生代理）。 此外，该系统具有“三层”体系结构和实现Java语言中的。我们可能想象的软件代理连接到每一个应用程序或辅导环境，每个都具有显式的表示的用户的目标，他们的计划和资源。这些代理商的沟通，并与对方进行谈判，以满足他们的个人或组目标。设计并实现了计算机内多代理辅导系统（MTS）研究集中在“建模”的学生，以科学系确定最适合的方法和辅导策略应考虑到个人知识和能力。这种系统的用户提供所有五种类型的先前描述的模式在他/她处置（工厂方法，生成器，命令，中保，观察员），其中将可以使用一个或多个，根据该系统的要求，需要加以设计。根据不同用户的需求，必须满足的要求的系统，其中选择来自老师的
45、代理设计模式最适合那些功能。 该模式可以帮助建立菜单的应用程序和用户接口。 然后，数据库建立，因为用户具有永久访问应用程序的一个例子，尽可能相似的一个，需要被执行。 为了开发一个应用程序，学生必须了解Java编程语言，必须熟悉与MySQL数据服务器必须能够使用Eclipse平台。 Eclipse平台是一个开源框架，旨在从IBM为软件开发人员提供了各种基本服务。4. 结论该系统希望是一个有用的应用软件开发工具培训，为学生和其他类型的用户。 并附上一个例子设计模式使用该模式有可能成为在软件设计中的一种方式工作。 此外，在这种情况下，申请开展一个面向对象的设计模式-因此设计原则-到一个可重用 的设计
46、和可重用的模块/组件的 应用效果 。另外，生成的代码享受更健壮性和灵活性 ，这两个特性开发新的模块，将增加新的功能和操作是必不可少的应用的设计/应用程序代码是开放的扩展和关闭的变化，根据OCP。另一个重要的方面涉及的 维护活动设计应用程序将发生沿其生命周期：它们会 更符合成本效益 ，没有变化在整个系统中传播，被内置的应用程序代码，以便它隔离挥发性类（根据扭转依赖性的原则）的依赖关系，即在路上“的细节取决于抽象化”周围而不是其他方式。软件模式确保符合设计原则，因为它们有助于获得一个稳定，高效的系统，并为学生提供设计学科。 最后，但并非至少使用这样的系统软件工程中的学习使得该过程更有吸引力的和高效
47、的。 设计模式的方法在软件工程培训适合教学架构理论（在开始的20创建的巴特利特日世纪）。 一培训领域的特定知识的简要表示可以帮助学员更容易吸收新的信息，而知识的组织和结构模式将引导他/她找到（记忆）在一定的必要的信息的上下文。 我们相信，在这样的做法，你可以创建一个培训本体软件工程。英文求职信Dear Sir or Madam,I would like to express my interest in applying for the summer positions with your company. Throughout my internship search and convers
48、ation with the recruiter, I have come to respect the professionalism that characterizes your firm and its employees. I am confident that the company teams values and objectives would complement my own strengths and enthusiasm. I would like to be considered for an information technology, computer sys
49、tem, software, electrical, or similar position that requires refined analytical and problem solving skills.As an Engineering student, competent leader and effective team builder with a lengthy experience; I possess a diverse background in assisting, planning, scheduling, developing, supporting, and management of various projects and activities, not limited to working with Verizon, Vgo, Samsung, Novatel, Alcatel-Lucent, Eric