Analysis and design of information system (CSE 302)

1. Analysis and design of information system (CSE 302) Chapter 1

2. Introduction to Information System Defining a system: A system is simply a set of component that interact to accomplish some task. Information system are those system that process information.

3. Role of Information system • Information system through their central role in the information economy(or IT) changes in four central ways: • People are working smarter. • The idea of industry is changed globally.(e.g. bank, brokers, insurance, real estate etc.) • Idea and information are taking precedence over money. • People who work for information are dominating the work force.

4. System Analysis and Design • System Design is the process of planning a new business system or to replace the existing system. • System Analysis is the process of gathering and interpreting facts, diagnosing problems, and using the information to recommend improvement to the system. • Analysis specifies what the system should do. Design states how to accomplish the objective.

5. System Analyst Work • Work depends on organization. Following are most common sets of responsibility assigned to system analyst. • System Analyst only. • System Analyst and Design. • System Analyst, Design and Programming. • The best qualified and most valuable system analyst know how to write program.

6. Type of End Users • Hand on end user: Operate the system. • Indirect end-user: Uses report or information produce by the system. • User manager: Have management responsibility for the application system. • Senior Manager: It consider the possible impact and benefit of information system.

7. System characteristics • Types of system: • Open system-Interact with environments. • Closed system-Does not interact with surrounding. • System work best in control when the operate in tolerable level. • All system have acceptable level of performance call standards.

8. System characteristics • Control system consist of: • A standard for acceptable performance. • A method of measuring actual performance. • A means of comparing actual performance against the standard. • A method of feed back.

9. Business system • Organization consist of many business system. • For example Manufacturing system. • To keep functioning Manufacturing system must meet performance standard. • Manufacturing system are self regulating and self adjusting. • The general feature of all the system are identical.

10. Business Information System • Like any other system information system take input, process the input and produce output. • Information system consist of sub system, including hardware, software and data storage. • Particular set of subsystem that uses specific equipment, program, file and procedure constitute and information system application.

11. Business Information System • Often organizational chart are used to describe how the organizational components are related. • Chart shows formal relationship but they do not tell how the organization work. • Other details that are required to analyze are • Information channel. • Interdependence. • Key people and function • Critical communication link.

12. Categories of Information System • System analysts developed several types of information system: • Transaction processing system • Management information system. • Decision support system

13. Categories of Information System Transaction Processing System- its aim is to improve the routine business activities on which all organization depend. Transaction is event or activity that effects organization. Eg- placing orders, billing customers, hiring employees etc…. Transaction processing is set of procedures for handling transaction, it include activities:

14. Transaction Processing System • Transaction processing includes • Calculation • Storage • Classification • Summarization • Sorting • Similar characteristic in each firms: • There is high volume of transactions • Each transaction is similar. • The process for transaction are well understood and can be describe in detail. • Few exception to normal procedure occurs. • This allows to establish routines. Eg- BANKING.

15. Transaction Processing System • When customers make withdrawals at ATM, the software used to operate system ensures that proper procedure is followed: COMPUTER ACTIVITY SYSTEM ACTIVITY Enter account no. Verify that account number is acceptable. Enter password. Verify that password is valid for account. Enter withdrawal amount. Verify that amount is within limits set by the bank and within account balance. Remove receipt and money. Issue receipt for transaction. Prepare for next transaction. • This activity will be repeated many times in a single day. • Transaction processing system provide speed and accuracy, and can e program to follow routines without any varance.

16. MANAGEMENT INFORMATION SYSTEM • MIS assist managers in decision making n problem solving. • Decision must be made on issues that reoccur regularly and require a certain set of information to make decision. • Information report are combined with other external information such as details about economic trends, demands of loan, rate of customer spending, and cost of borrowing.

17. DECISION SUPPORT SYSTEM • DSS assists managers who must make decision on Unstructured or semi structured. • Unstructured: if there is no clear procedures for making decision. If all the factors are not identified in advance in decision. • Well Structured- if all the factors are identified in advance which help in decision making. • Use of DSS is to determine what information is needed. Sometimes, additional information is required to improve our systems.

18. SYSTEM DEVELOPMENT STRATEGIES • The three different approaches to development of computer information system: • System development life cycle method • Structured analysis development method. • System prototype method.

19. SYSTEM DEVELOPMENT LIFE CYCLE SDLC is a set of activities that analysts, designers, and users carry out to develop and implement an information system. SDLC method consist of following activities: • Preliminary investigation. • Determination of system requirements. • Design of system. • Development of software. • System testing. • Implementation and evaluation.

20. PRELIMINARYINVESTIGATION • When a request is initiated by a manager, employee or by some specialist, first activity is investigation begins. This activity has three parts: • Request clarification. • Feasibility study. • Request approval. • Request clarification: before investigation of system, the request must be examined to determine what the originator wants. • Feasibility study: to determine whether system requested is feasible or not. Types of feasibility study of investigation-Technical feasibility, Economic feasibility , Operational feasibility.

21. PRELIMINARYINVESTIGATION • Request approval: to take the project for approval. After its approval, its cost, priority, completion time n requirements are estimated and used to determine where to add it to existing project list.

22. SYSTEM REQUIREMENTS • Analyst must study the business process to answer the following: • What is being done? • How is it being done? • How frequently does it occur? • How well is the task being performed? • Does a problem exist? • If a problem exists, how serious is it? • If a problem exists, what is underlying cause? • To answer these questions, detailed investigation required, study of manuals, collection of samples to understand the process.

23. DESIGN OF SYSTEM • The design of IS produce the details that state of how a system will meet the requirements identified during system analysis. This stage is called logical design. • Designers sketch the report when system is completed. • System design describes data to be input, calculated or stored. Designers select file structures and storage devices like magnetic disk, magnetic tapes.

24. DEVELOPMENT OF SOFTWARE • System developers may install, purchased software or they may write new custom designed programs. • The choice depends on cost of each option, time available to write program h availability of programmers. • Programmers are also responsible for documenting the programs.

25. SYSTEM TESTING • To experiment the system to ensure that software doesn’t fail. • To check that it is running according to its specification and in the way user expect. • A limited no. of users may be allowed to use system. • In many organizations, testing is performed by persons other than those who wrote the original program to ensure more complete n more reliable software.

26. IMPLEMENTATION AND EVALUATION • It is the process of having system personnel checkout and put new equipment into use, train users, install new application. • Sometimes system developers run the old and new systems together to compare the results. • Since IS and business organizations undergo continual change, the IS should keep pace. In this sense, implementation is ongoing process. • Evaluation of system is performed to identify its strengths n weaknesses.

27. IMPLEMENTATION AND EVALUATION The dimensions used for actual evaluation are as follows: • Operational evaluation. • Organizational impact. • User management assessment. • Development performance.

28. STRUCTURED ANALYSIS DEVELOPMENT METHOD The structured analysis development method is aimed on: 1) partition the system into components 2) constructing model of system. What is structured analysis? It focuses on specifying what system is required to do. Elements of structured analysis It includes graphic symbols, data flow diagrams, a centralized data dictionary.

29. STRUCTURED ANALYSIS DEVELOPMENT METHOD • Graphical description: uses symbols, or icons to create a graphic model of system. • Data flow diagrams: full description of system consists of set of data and flow diagrams. • Data dictionary: definition of elements of system like data stores, data flows n processes.

30. WHAT IS STRUCTURED DESIGN?? • It focuses on the development of software specification. • Goal is to create programs consisting of functionally independent modules. • Fundamental tool used is STRUCTURE CHART. Process customer payment Apply customer payment

31. SYSTEM PROTOTYPE METHOD • Users are directly involved in system. • This method is useful only if it is employed at right time n in appropriate manner. • What is prototype? • It is a working system that is developed to test ideas n assumptions about new system. • It consists of working software that accepts input, perform calculations n produced printed information, perform meaningful activities.

32. SYSTEM PROTOTYPE METHOD Prototyping is useful under following conditions: • No system with characteristics of one proposed system has yet been constructed by the developers. • The essential features of system are only partially known. • Experience in using the information will significantly add to the list of requirements. • Alternate versions of system involve additional development and refinement of features. • The system users will participate in the development process.

33. SYSTEM PROTOTYPE METHOD Steps in prototyping process: • Identify the users known information requirement and features needed in system • Develop a working prototype. • Use the prototype for further enhancement and changes. This expand the list of system requirement. • Revise the prototype based on information gained through user experience. • Repeat these steps as needed to achieve a satisfactory system.

34. SYSTEM PROTOTYPE METHOD • When sufficient information has been collected one of the following alternative is selected: • The prototype is developed from scratch. • The prototype is implemented as the complete system. • The project is abandoned. • Another prototyping series is begun.