新编-面向对象系统分析与设计-精品课件.ppt

1、面向对象系统分析与设计面向对象系统分析与设计 Object-Oriented Systems Analysis and Design河北农业大学信息科学与技术学院滕桂法 教授主要内容主要内容1、系统分析与设计概论、系统分析与设计概论2、面向对象概念与术语、面向对象概念与术语3、面向对象分析与设计、面向对象分析与设计4、面向对象编程、面向对象编程5、UML面向对象设计基础面向对象设计基础6、UML面向对象开发第一章第一章 系统分析与设计概论系统分析与设计概论(System Analysis and Design)Chapter Objectives(You should be able to)1

2、.Define a system,information system,and automated information system.2.Define the basic components and the basic characteristics of an automated information system.3.Define system analysis and design and discuss why it is a difficult human endeavor.4.Describe the skills and activities of a system an

3、alyst.系统分析与设计概论系统分析与设计概论(System Analysis and Design)5.Describe a general model of the analysis,design,and implementation process.6.Discuss systems analysis and design as a career.7.Discuss what a system analyst does.8.Discuss systems analysis and design projects and where they come from.9.Discuss th

4、e need for creating information systems requirements specifications.系统分析与设计概论系统分析与设计概论(System Analysis and Design)10.Define and describe the information systems life cycle.11.Define and describe the information system development life cycle.12.Discuss the principles used to guide system analysis and

5、 design.系统分析与设计概论系统分析与设计概论(System Analysis and Design)Development Process Systems planning Systems analysis System design Systems implementation Systems evolution系统分析与设计概论系统分析与设计概论(System Analysis and Design)2.Concept of System Analysis and Design What is a system?A system is a set of interrelated c

6、omponents,working together for a common purpose.There are two types of systems:natural and fabricated.系统分析与设计概论系统分析与设计概论(System Analysis and Design)System Model with Six Components:systemboundarycontrolsprocessinginputsfeedbackoutputs系统分析与设计概论系统分析与设计概论(System Analysis and Design)What is an informati

7、on system?An information system is a type of fabricated system that is used by one or more persons to help accomplish a task or assignment.系统分析与设计概论系统分析与设计概论(System Analysis and Design)What is an information system?datapeopleprocedures系统分析与设计概论系统分析与设计概论(System Analysis and Design)What is an automate

8、d information system?A automated information system is an information system that incorporates the use of computer hardware and software as part of the system.系统分析与设计概论系统分析与设计概论(System Analysis and Design)What is an automated information system?datapeoplesoftwareprocedureshardware系统分析与设计概论系统分析与设计概论(

9、System Analysis and Design)What are the basic characteristics of an information system?The basic characteristics that exist within an information system are data,functions,and behavior,as illustrated in the following figure.DataFunctionsBehavior系统分析与设计概论系统分析与设计概论(System Analysis and Design)What are

10、the basic characteristics of an information system?Data:input,stored,or output Function:business activity performed Behavior:the observable effects of a request 系统分析与设计概论系统分析与设计概论(System Analysis and Design)What is systems analysis and design?System analysis and design is about developing software,b

11、ut it is more about developing a complete automated information system,which includes hardware,software,people,procedures,and data.These five components exist in virtually all automated information systems,although the amount of each will vary with respect to the specific system being developed.All

12、of these components must be considered and addressed during system analysis and design.系统分析与设计概论系统分析与设计概论(System Analysis and Design)Actors of systems analysis and design?System Analyst;System Engineer;Programmer;Architect;系统系统分析分析与设与设计过计过程程系统系统分析分析与设与设计过计过程程系统分析与设计概论系统分析与设计概论(System Analysis and De

13、sign)What makes systems analysis and design such a difficult human endeavor?Seven reasons:1.Analysis problems,at their inception,have ill-defined boundaries and structure(users are not certain of what they want),and have a sufficient degree of uncertainty about the nature of the solution.系统分析与设计概论系统

14、分析与设计概论(System Analysis and Design)What makes systems analysis and design such a difficult human endeavor?2.The solutions systems analysts come up with to solve the problems are artificial,and since they are designed by humans with different backgrounds,experiences,biases,and so on,there exists an e

15、ndless variety of potential solutions.That means that there is no single correct solution to a problem.Many needs and Many solutions.系统分析与设计概论系统分析与设计概论(System Analysis and Design)What makes systems analysis and design such a difficult human endeavor?3.Analysis problems are dynamic.No business is sta

16、nding still.Change!4.The solutions to analysis problems require interdisciplinary knowledge and skills,hence,the need for a team approach to IS development.Emphasis on the partnership concept between the user community and the IS developers.系统分析与设计概论系统分析与设计概论(System Analysis and Design)What makes sy

17、stems analysis and design such a difficult human endeavor?5.The knowledge base of the systems analysis is continually evolving.As the apprentice systems analyst progresses through the junior,associate,and senior systems analyst ranks over time,he or she continues to learn more about business problem

18、 domains as well as improving his or her analytical skills and software development tool and technique skills.系统分析与设计概论系统分析与设计概论(System Analysis and Design)What makes systems analysis and design such a difficult human endeavor?6.The process of analysis is primarily a cognitive activity in that we ar

19、e asked to(1)put structure to an abstract problem domain,(2)process diverse information from a variety of users,and(3)develop a logical and consistent specification that will lead to the creation of a successful information system.7.The People!Study human and org.behavior.Stakeholders:Players in the

20、 Systems Development Team A stakeholder is any person who has an interest in an existing or new information system.Stakeholders can be technical or nontechnical workers.For information systems,the stakeholders can be classified as(six groups of information workers):System owners System users Systems

21、 analysts System designers System builders IT vendors and consultantsInformation versus Knowledge WorkersInformation workers are those workers whose jobs involve the creation,collection,processing,distribution,and use of information.(In USA they are so called)Knowledge workers are a subset of inform

22、ation workers whose responsibilities are based on a specialized body of knowledge.(College educated;Depending on information and ability to properly use and react to information)System OwnersSystem owners are the information systems sponsors and chief advocates.They are usually responsible for fundi

23、ng the project to develop,operate,and maintain the information system.System UsersSystem users are the people who use or are affected by the information system on a regular basiscapturing,validating,entering,responding to,storing,and exchanging data and information.A common synonym is client.Types i

24、nclude:Internal users Clerical and service workers Technical and professional staff Supervisors,middle managers,and executive managers Remote and mobile users(internal but disconnected)External users(customer and other system users)System Designers and System BuildersSystem designers translate syste

25、m users business requirements and constraints into technical solutions.They design the computer files,databases,inputs,outputs,screens,networks,and programs that will meet the system users requirements.System builders construct the information system components based on the design specifications fro

26、m the system designers.In many cases,the system designer and builder for a component are one and the same.Systems AnalystsA systems analyst studies the problems and needs of an organization to determine how people,data,processes,communications,and information technology can best accomplish improveme

27、nts for the business.When information technology is used,the analyst is responsible for:The efficient capture of data from its business source,The flow of that data to the computer,The processing and storage of that data by the computer,and The flow of useful and timely information back to the busin

28、ess and its people.Variations on the Systems Analysts Title A business analyst is a systems analyst that specializes in business problem analysis and technology-independent requirements analysis.A programmer/analyst(or analyst/programmer)includes the responsibilities of both the computer programmer

29、and the systems analyst.Other synonyms for systems analyst include:Systems consultant Systems architect Systems engineer Information engineer Systems integratorProblem-Solving Scenarios True problem situations,either real or anticipated,that require corrective action Opportunities to improve a situa

30、tion despite the absence of complaints Directives to change a situation regardless of whether anyone has complained about the current situationGeneral Problem-Solving Approach1.Identify the problem.2.Analyze and understand the problem.3.Identify solution requirements or expectations.4.Identify alter

31、native solutions and decide a course of action.5.Design and implement the“best”solution.6.Evaluate the results.If the problem is not solved,return to step 1 or 2 as appropriate.Where Systems Analysts Work In traditional businesses Working in traditional information services organizations(permanent p

32、roject teams)Working in contemporary information services organizations(dynamic project teams)In outsourcing businesses Contracted to traditional businesses In consulting businesses Contracted to traditional businesses In application software businesses Building software products for traditional bus

33、inessesTraditional IS Services OrganizationContemporary IS Services OrganizationBusiness Trends and Drivers Total quality management(TQM)Continuous process improvement(CPI)Globalization of the economy Information technology problems and opportunities Year 2000 problem(Y2K)Euro currency directive Ent

34、erprise resource planning(ERP)Electronic commerce(EC or E-commerce)Total Quality Management Total quality management(TQM)is a comprehensive approach to facilitating quality improvements and management within a business.Information systems quality standards:ISO 9001,Quality systems Model for quality

35、assurance in design/development,production,installation,and servicing.Capability Maturity Model(CMM)is a framework to assess the maturity level of an organizations information systems development and management processes and products.It consists of five levels of maturity as measured by a set of gui

36、delines called the key process areas.The CMM Process Management ModelThe Capability Maturity Model(CMM)is a framework to assess the maturity level of an organizations information system development and management processes and products.It consists of five levels of maturity as measured by a set of g

37、uidelines called the key process areas.Level 1Initial:System development projects follow no prescribed process.Level 2Repeatable:Project management processes and practices are established to track project costs,schedules,and functionality.Level 3Defined:A standard system development process(sometime

38、s called a“methodology”)is purchased or developed,and integrated throughout the information systems/services unit of the organization.Level 4Managed:Measurable goals for quality and productivity are established.Level 5Optimizing:The standardized system development process is continuously monitored a

39、nd improved based on measures and data analysis established in Level 4.The CMM Process Management ModelLevel5OPTIMIZEDLevel4MANAGEDLevel3DEFINEDLevel2REPEATABLERISKCOMPETITIVENESSLevel1INITIALBusiness Process RedesignBusiness process redesign(BPR)is the study,analysis,and redesign of fundamental bus

40、iness processes to reduce costs and/or improve value added to the business.Usually complemented by continuous process improvementContinuous Process ImprovementContinuous process improvement(CPI)is the continuous monitoring of business processes to effect small but measurable improvements to cost red

41、uction and value added.Essentially the opposite of business process redesign;however,CPI can and frequently does complement BPR.Legacy SystemsLegacy systems are older information system applications that have become crucial to the day-to-day operation of a business and that may use technologies cons

42、idered old or outdated by current standards.Can be adversely affected by technology and economic forces:Year 2000 Euro Can be replaced by alternative solutions:ERP E-CommerceEnterprise Resource PlanningAn Enterprise resource planning(ERP)software product is a fully integrated information system that

43、 spans most basic business functions required by a major corporation.An ERP product is built around a common database shared these business functions.Examples of ERP software vendors include.Baan J.D.Edwards Oracle Peoplesoft SAPElectronic CommerceElectronic commerce(e-commerce or EC)involves conduc

44、ting both internal and external business over the Internet,intranets,and extranets.Electronic commerce includes the buying and selling of goods and services,the transfer of funds,and the simplification of day-to-day business processes all through digital communications.Three basic types of electroni

45、c commerce applications include:Marketing Business-to-consumer(B2C)Business-to-business(B2B)The Systems Analyst as a FacilitatorSkills Required by Systems Analysts Working knowledge of information technology Computer programming experience and expertise General business knowledge Problem-solving ski

46、lls Interpersonal communication skills Interpersonal relations skills Flexibility and adaptability Character and ethics Systems analysis and design skillsThe Ten Commandments of Computer Ethics1.Thou shalt not use a computer to harm other people.2.Thou shalt not interfere with other peoples computer

47、 work.3.Thou shalt not snoop around in other peoples computer files.4.Thou shalt not use a computer to steal.5.Thou shalt not use a computer to bear false witness.6.Thou shalt not copy or use proprietary software for which you have not paid.7.Thou shalt not use other peoples computer resources witho

48、ut authorization or proper compensation.8.Thou shalt not appropriate other peoples intellectual output.9.Thou shalt think about the social consequences of the program you are writing or the system you are designing.10.Thou shalt always use a computer in ways that insure consideration and respect for

49、 your fellow humanComputer Ethics Source:Computer Ethics Institute Source:Computer Ethics InstituteInformation System Building BlocksInformation System Building BlocksWhat are information systems,and who are the stakeholders in the information systems game?Describe the difference between data and in

50、formation.Define the product called an information system,and describe the role of information technology in information systems.Differentiate between front-and back-office information systems.Describe five classes of information system applications(transaction processing,management information,deci