系统的分析与设计外文翻译

1、i 1 引 言如今的世界，已经是步入了信息化的时代，特别是互联网的迅猛发展，带动了信息进入我们生活的各个领域，也使得信息化建设成为各行业、各领域增强自身管理效率和核心竞争力的重要手段。出版业作为我国社会主义文化产业的一部分，在信息化建设方面相对于其他领域，有成绩是肯定的，但仍然显得滞后，建设水平不够高，离市场需求还有一定距离，还有很大的发展潜力，在我国信息化建设中应该发挥更大的作用。同时要充分利用先进的电子信息技术改造出版业，来加快出版业信息化建设的步伐。出版社信息化建设是用一种全新的、先进的管理理念，一种全新的机制，一种全新的企业文化来改变以前的管理模式，是一种管理模式的变革。它充分利用信息

2、技术与出版社管理模式的结合，来推动管理水平的提升。面对日益激烈的竞争，出版社必须转变思路，确立全新的经营理念，确立以读者需求为中心，提供专业化的一流服务。信息化建设更是一场管理体制的革命，它要用先进的思想模式和技术手段改变以前的管理模式，用数字化、规范化、程序化、标准化来进行管理，用量化的指标支持奖惩与分配政策，体现激励机制。通过这场改革和革命，最终实现出版社的办公自动化、管理网络化、资源数字化、商务电子化。而在整个的出版过程中，编务管理是出版行业信息管理系统的重要部分,它将编务人员及图书管理人员从繁重的事务性工作中解放出来,并使管理工作更透明、更科学,此次的系统如果有了良好的分析与设计,不但

3、对编务管理,而且对整个出版行业的管理信息系统的建设都具有十分重要的意义。本文将以北京科学技术出版社为例，为出版企业编务管理部门的信息化建设提出一个可行性方案，为将来的出版社进行信息化建设打下良好的基础。附录1 外文翻译(原文)systems analysis and design working under control of a stored program, a computer processes data into information. think about that definition for a minute. any given computer application

4、 involves at least three components: hardware, software, and data. merely writing a program isnt enough; because the program is but one component in a system.a system is a group of components that work together to accomplish an objective. for example, consider a payroll system. its objective is payi

5、ng employees. what components are involved? each day，employees record their hours worked on time cards. at the end of each week, the time cards are collected and delivered to the computer center, where they are read into a payroll program. as it runs, the program accesses data files. finally, the pa

6、ychecks are printed and distributed. for the system to work, people, procedures, input and output media, files, hardware, and software must be carefully coordinated. note that the program is but one component in a system.computer-based systems are developed because people need information. those peo

7、ple, called users, generally know what is required, but may lack the expertise to obtain it. technical professionals, such as programmers, have the expertise, but may lack training in the users field. to complicate matters, users and programmers often seem to speak different languages, leading to co

8、mmunication problems. a systems analyst is a professional who translates user needs into technical terms, thus serving as a bridge between users and technical professionals.like an engineer or an architect, a systems analyst solves problems by combining solid technical skills with insight, imaginati

9、on, and a touch of art. generally, the analyst follows a well-defined, methodical process that includes at least the following steps;1. problem definition2. analysis3. design4. implementation 5. maintenanceat the end of each step, results are documented and shared with both the user and the programm

10、ers. the idea is to catch and correct errors and misunderstandings as early as possible. perhaps the best way to illustrate the process is through example.picture a small clothing store that purchases merchandise at wholesale, displays this stock, and sells it to customers at retail. on the one hand

11、, too much stock represents an unnecessary expense. on the other hand, a poor selection discourages shoppers. ideally, a balance can be achieved: enough, but not too much.complicating matters is the fact that inventory is constantly changing, with customer purchases depleting stock, and returns and

12、reorders adding to it. 1 the owner would like to track inventory levels and reorder and given item just before the store runs out. for a single item, the task is easy-just count the stock-on-hand. unfortunately, the store has hundreds of different items, and keeping track of each one is impractical.

13、 perhaps a computer might help.2-1 problem definitionthe first step in the systems analysis and design process is problem definition. the analysts objective is determining what the user (in this case, the stores owner) needs. note that, as the process begins, the user possesses the critical informat

14、ion, and the analyst must listen and learn. few users are technical experts. most see the computer as a magic box, and are not concerned with how it works. at this stage, the analyst has no business even thinking about programs, files, and computer hardware, but must communicate with the user on his

15、 or her own term.the idea is to ensure that both the user and the analyst are thinking about the same thing-thus, a clear, written statement expressing the analysts understanding of the problem is essential. the user should review and correct this written statement. the time to catch misunderstandin

16、gs and oversights is now, before time, money and effort are wasted.often, following a preliminary problem definition, the analyst performs a feasibility study. the study a brief capsule version of the entire systems analysis and design process, attempts to answer three questions:1. can the problem b

17、e solved?2. can it be salved in the users environment?3. can it be solved at a reasonable cost?if the answer to any one of these questions is no, the system should not be developed. given a good problem definition and a positive feasibility study, the analyst can turn to planning and developing a pr

18、oblem solution.2- 2 analysisas analysis begins, the analyst understands the problem. the next step is determining what must be done to solve it. the user knows what must be done 1 during analysis; this knowledge is extracted and formally documented. most users think in terms of the functions to be p

19、erformed and the data elements to be manipulated. the objective is to identify and link these key functions and data elements, yielding a logical system design.start with the systems basic functions. the key is keeping track of the stock-on-hand for each product in inventory. inventory changes becau

20、se customers purchase, exchange, and return products, so the system will have to process customer transactions. the stores owner wants to selectively look at the inventory level for any product in short supply and, if appropriate, order replacement stock, so the system must be able to communicate wi

21、th management. finally, following management authorization, the system should generate a reorder ready to send to a supplier.fig 1given the systems basic functions, the analysts next task is gaining a sense of their logical relationship. a good way to start is by describing how data flow between the

22、 functions. as the name implies, data flow diagrams are particularly useful for graphically describing these data flows. four symbols are used (fig. 1). data sources and destinations are represented by squares; input data enter the system from a source, and output data flow to a destination. once in

23、 the system, the data are manipulated or change by processes, represented by round-corner rectangles. a process might be a program, a procedure, or anything else that changes or moves data. data can be held for later processing in data stores, symbolized by open-ended rectangles. a data store might

24、be a disk file, a tape file, a database, written notes, or even a persons memory. finally, data flow between sources, destinations, processes, end data stores over data flows, which are represented by arrows.fig 2figure 2 shows a preliminary data flow diagram for the inventory system. start with cus

25、tomer. transactions flow from a customer f into the system, where they are handled by process transaction. a data store, stock, holds data on each item in inventory. process transaction changes the data to reflect the new transaction. meanwhile, management accesses the system through communicate, ev

26、aluating the data in stock and, if necessary, requesting a reorder. once, a reorder is authorized. generate reorder sends necessary data to the supplier, who ships the items to the store. note that, because the reorder represents a change in the inventory level of a particular product or products it

27、 is handled as a transaction.the data flow diagram describes the logical system. the next step is tracing the data flows. start with the destination supplier. reorders flow to suppliers; for example, the store might want 25 pairs of jeans. to fill the order, the supplier needs the product descriptio

28、n and the reorder quantity. where do these data elements come from? since they are output by generate reorder, they must either be input to or generated by this process. data flow into generate reorder for stock; thus, product descriptions and reorder quantities must be stored in stock.other data el

29、ements, such as the item purchased and the purchase quantity are generated by customer. still others, for example selling price and reorder point, are generated by or needed by management. the current stock-on-hand for a given item is an example of a data element generated by an algorithm in one of

30、the procedures. step by step, methodically, the analyst identifies the data elements to be input to .stored by, manipulated by, generated by, or output by the system.to keep track of the data elements, the analyst might list each one in a data dictionary. a simple data dictionary can be set up on in

31、dex cards, but computerized data dictionaries have become increasingly popular. the data dictionary, a collection of data describing and defining the data, is useful throughout the systems analysis and design process, and is often used to build a database during the implementation stage.the idea of

32、analysis is to define the systems major functions and data elements methodically. remember that the objective is translating user needs into technical terms. since the system starts with the user, the first step is defining the users needs. users think in terms of functions and data. they do not vis

33、ualize programs, or files, or hardware .and during this initial, crucial analysis stage it is essential that the analyst think like a user, not like a programmer.data flow diagrams and data dictionaries are useful tools. they provide a format for recording key information about the proposed system.

34、also, they jog the analysts memory) for example, if the analyst doesnt have sufficient information to complete a data dictionary entry, he or she has probably missed something. perhaps most importantly, the data flow diagram and the data dictionary document the analysts understanding of the system r

35、equirements. by reviewing these documents, the user can correct misunderstandings or oversights. finally, they represent an excellent starting point the next step, design.2-3 designas we enter the design stage, we know what the system must do, and thus can begin thinking about how to do it. the obje

36、ctive is to develop a strategy for solving the problem. at this stage, we are not interested in writing code or in defining precise data structures; instead, we want to identify, at a black box level, necessary programs, files, procedures, and other components.the data flow diagram defines the syste

37、ms necessary functions; how might they be implemented? one possibility is writing one program for each process. another is combining two or more processes in a single program; there are dozens of alternative solutions. lets focus on one option and document it.a system flowchart uses symbols to repre

38、sent programs, procedures, hardware devices, and the other components of a physical system (fig. 3). our flowchart (.fig. 4) shows that transaction data enter the system through a terminal, are processed by a data collection program, and then are stored on an inventory file. eventually, the inventor

39、y file is processed by a report and reorder program. through it, management manipulates the data and authorizes reorders.fig. 4 on a system flowchart, symbols represent programs, procedures, hardware devices, and the other components of a physical system.fig 3look at the system flowchart. it identif

40、ies several hardware components, including a computer, a disk drive, a data entry terminal, a printer, and a display terminal. two programs are needed; process transaction and report and reorder. in addition to the hardware and the programs, well need data structures for the inventory file and for d

41、ata flaws between the i/o devices and the software. note that this system flowchart illustrates one possible solution; a good analyst will develop several feasible alternatives before choosing one.fig 4the flowchart maps the system, highlighting its major physical components. since the data link the

42、 components, the next task is defining the data structures. consider, for example, the inventory file. it contains all the data elements from the data store stock. the data elements are listed in the data dictionary. using them, the files data structure can be planned,how should the file be organize

43、d? that depends on how it will be accessed. for example, in some applications, data are processed at regular, predictable intervals. typically, the data are collected over time and processed together, as a batch. if batch processing is acceptable, a sequential file organization is probably best.it i

44、s not always possible to wait until a batch of transactions is collected, however. for example, consider an air defense early warning system. if an unidentified aircraft is spotted it must be identified immediately the idea of waiting until 5 _ 00 p.m. because thats when the air defense program is r

45、un is absurd. instead, because of the need for quick response, each transaction must be processed as it occurs. generally such transaction processing systems call for direct access file.our inventory system has two programs. one processes transactions. a direct access inventory file seems a reasonab

46、le choice. the other allows management to study inventory data occasionally; batch processing would certainly do. should the inventory file be organized sequentially or directly? faced with such a choice a good analyst considers both options. one possible system might accept transactions and process

47、 them as they occur. as an alternative, sales slips might be collected throughout the day and processed as a batch after the store closes. in the first system, the two programs would deal with direct access files; in the second system, they would be linked to sequential files. a program to process d

48、irect access data is different from a program to process sequential data. the data drive the system. the choice of a data structure determines the programs structure. note that the program is defined and planned in the context of the system.2- 4 implementationonce the systems major components have b

49、een identified .we can begin to develop them. our system includes two programs, several pieces of equipment, and a number of data structures. during implementation, each program is planned and written using the techniques described in chapter 7. files are created, and their contents checked. new har

50、dware is purchased, installed, and tested. additionally, operating procedures are written and evaluated. once all the component parts are ready, the system is tested. assuming the user is satisfied, the finished system is released.2- 5 maintenancemaintenance begins after the system is released. as p

51、eople use it, they will suggest minor improvements and enhancements. occasionally, bugs slip through debug and testing, and removing them is another maintenance task. finally, conditions change, and a program must be updated; for example, if the government passes a low changing the procedure for col

52、lecting income taxes, the payroll program must be modified. maintenance continues for the life of a system, and its cost can easily match or exceed the original development cost. good planning, solid documentation, and well-structured programs can help to minimize maintenance cost.附录2 外文翻译(译文)系统的分析与

53、设计 在存储程序的控制下，计算机把数据处理成信息。对系统的定义略加思考，任何一个已知的计算机应用至少包含三个部分，硬件、软件和数据。仅仅编写一个程序是不够的，因为程序只是系统中的一部分。 系统就是为实现一个目标而共同工作的一组部件。例如，考虑一个工资系统，它的目标是为雇员付工资，应包含哪几部分呢？每天雇员们把他们工作的时数记录在计时卡片上，每周末把计时卡片收集起来，送给计算中心，在计算中心把计时卡片上的数据读给工资程序。当工资程序执行时，程序存取数据文件。最后，打印出工资单，用来分发。为使系统工作，人、处理过程、输入和输出介质、文件、硬件和软件都必须认真地协调。注意，程序只是系统中的一部分。

54、因为人们需要信息，所以要开发基于计算机的系统。被称为用户的那些人常常知道需求什么信息，但是他们可能缺乏得到这些信息的计算机的专门知识。计算机技术方面的专业人员，例如程序设计员有这方面的专门知识，但是可能在用户的专业领域内缺少训练。麻烦的是。用户和程序员似乎常常讲不同的语言，导致了两者之间的联系障碍。系统分析员是一个专业人员，他能把用户的需求转换成计算机技术术语。因此他是用户和技术专业人员之间的桥梁。 像工程师或建筑师一样，系统分析员把他扎实的技术技能与知识、想象力和一点艺术结合起来去解决问题通常，分析员遵循一个意义明确的有条理的过程，至少应包括以下几个步骤： 1问题的定义 2分析 3设计 4实

55、现 5维护 在每一步骤的结尾，研究的结果都要形成文件，提供给用户和程序设计员。基本的思想是要尽早地抓住和修正错误以及一些未理解之处。也许通过一个例子来说明该过程是最好的方法。 设想一个小服装店，成批地购买货物，把货物摆在货架上，零售给顾客。一方面库存太多会造成不必要的开销；另一方面可供挑选的商品太少会使顾客失去购买的信心。理想上，希望达到一个平衡，货物即充足但又不太多。麻烦的是，随着顾客的购买库存减少了，还有退货以及追加订货等情况，所以货物的清单经常地发生变化店主喜欢按货物清单购销，刚好在商店售完某种货物之前，再订购这种货。对一项商品，该任务是容易完成的，只要计算一下手头现存的货物数量就行了。

56、遗憾的是商店要经管几百种不同的货物，始终跟踪每一种货物的销售情况是不实际的，也许计算机可以帮这个忙吧！2.1问题定义 在系统分析和设计过程中的第一步，是问题的定义。分析员的目标是确定用户需求什么（本例中就是店主需求什么）。注意，当这个过程开始时，用户拥有很重要的资料，分析员必须认真地听和学。用户几乎都不是计算机方面的专家，他们大多数人把计算机看成魔术盒，并不关心它是如何工作的。在该阶段上，分析员不必考虑程序、文件或计算机硬件，但他们必须用自己的专业术语与用户对话。 目的是确保用户和分析员两者都思考同一件事。因此，一份能表达分析员对问题理解程度的清晰的书面报告是必要的。用户应该反复地阅读和修改这

57、份书面报告。此时是在时间、金钱和精力被浪费之前抓出错误和疏漏的好时机。 通常，接着初步的问题定义，分析员要进行可行性研究。该研究是整个系统分析和设计的一个简略的方案，应力图回答以下三个问题： 1问题能解决吗？ 2在用户的环境下问题能解决吗？ 3在一个合适的花费上问题能解决吗？如果这些问题中的任何一个得到的是否定回答，那么该系统就不应开发。有了好的问题定义和肯定的可行性研究，分析员就能着手计划和研究问题的解了。2.2分析 分析开始时，分析员要理解问题，下一步要决定的是为了解决问题必须做什么。用户清楚必须做什么。在分析阶段碍到了这方面知识，并正式地形成文件。大多数用户是按着所要完成的功能和所要处理

58、的数据元素去思考的，目的是要区分并联接这些关键的功能和数据元素，随之产生逻辑系统设计。 从系统的基本功能入手，关键是始终监视货单中每种商品的现存量。因为顾客购买、换货和退货，所以货单要改变，因此系统必须处理顾客办理的手续。店主希望有选择地查看供应中任意一种短缺商品的清单，如果合理的话，定货补充库存，因此系统必须能和经营管理部门对话。最后，经过经营管理部门的核准，系统应该产生一个重新订货单，准备发送给供应商。图 1 已知了系统的基本功能，分析员的下一个任务是分析理解这些功能之间逻辑关系的知识。启动这项工作的一个好方法是描述功能之间的数据如何流动顾名思义，为了用图解方法描述这些数据流，那么数据流程图就是特别有用的图1中用到四种符号数据的像和目的地用方框表示，输入的数据从源进入系统，而输出的数据流到目的地。数据一进入系统，就被若干进程加工或改变，用圆角的矩形表示这些过程。进程可以是程序、过程以及能够改变或传送数