Development of information system chap 2

This ppt presents how information system will be developed

1. 1 CHAPTER 2 INFORMATION SYSTEMS DEVELOPMENT https://www.youtube.com/watch?v=_oLKZB9jHIo&t=24s

2. Introduction Organizations use a standard set of steps, called a systems development methodology , to develop and support their information systems. It is a standard process followed in an organization to conduct all the steps necessary to analyze, design, implement, and maintain information systems Like many processes, the development of information systems often follows a life cycle. The systems development life cycle ( SDLC ) is a common methodology for systems development in many organizations. SDLC is The series of steps used to mark the phases of development for an informatio n system.

3. Information Systems Analysis and Design: core concepts. Systems Analysis: Systems Analysis is the study of a business problem domain for the purpose of recommending improvements and specifying the business requirements for the solution. Systems Design: Systems Design is the specification or construction of a technical, computer based solution for the business requirements identified during systems analysis. Systems Analysis and Design (SAD): Is a method used by companies to creat e and maintain information systems that perform basic business functions.

4. Cont. The main goal of SAD is to improve organizational systems through developing or acquiring application software that can help employees to accomplish key business tasks more easily and efficiently. An application software is designed to support a specific organizational function or process, such as inventory management , payroll . The goal of application software is to turn data into information. An Information System is developed by following Software Engineering Process, which consists of proven methodologies , techniques and tool. These three process work together to form an organization approach to SAD

5. Cont. An Information System is developed by the following Software Engineering Process

6. Cont. Methodologies are sequence of step by step approaches that helps to develop the final product. The methodologies incorporate techniques like, direct observations and interviews with users. Techniques provide support for a wide range of tasks including conducting interviews with users, planning and managing the activities of a project and designing the reports. Tools are computer programs, such as computer aided software engineering (CASE) tools, that make it easy to use specific techniques. 6

7. Approach to system Analysis and Design Process-oriented approach Data-oriented approach Object-oriented approach 7

8. Process-oriented approach Traditionally, Systems Analysts, designed an Information System based on what the system was meant to do , such as billing or inventory control . The focus was on outputs and processing logic. Each system would contain its own files and data storage areas The data in each system would match the specifications for that system only. Each systems was considered ( looked at) separately 8

9. Cont. The analysis involved in creating drawings / diagrams that show how the data moves around the system and where it is stored in between flows. The problems with this approach are, The existence of several files of data each locked with different applications and programs. many of the files in different applications contains same data, updating the data becomes tedious process, it also difficult to combine data files created for specific applications. 9

10. example 10

11. Data Oriented approach This approach tends to focus on how the data should be represented independently of where and how data are used in the system A data model is produced, which describes the data and relationships between the data. Business rules define how the organization deals with the data Databases are designed around the subjects such as customers, suppliers , parts. This lets to use the databases for many different applications. This means that the application is independent of data and data definitions it is called as application independence

12. Cont. Today, systems development focuses on systems integration. Systems integration allows hardware and software from different vendors to work together in an application. 12

13. Object-oriented approach Based on objects rather than data or process Emphasis here is re-usability via reusable objects and components . Component-based software development . For non-available components, developer may prototype needed modules, use an SDLC approach, purchase libraries of objects, develop ‘his’ own, etc.

14. Systems Development Life Cycle (SDLC The series of steps used to mark the phases of development for an information system. It is a common methodology for systems development. What are the phases of the system development cycle ? 3/14/2024 SA-ISB-4-1 14

15. 3/14/2024 15 2.2. Software Development Life Cycle- Detailed Each phase has specific outcomes and deliverables that feed important information to other phase. Phase 1. Planning Phase 2. Analysis Phase 3. Design Phase 4. Implementation Phase 5. Support/Evaluation Review project requests Prioritize project requests Allocate resources Identify project development team Conduct preliminary investigation Perform detailed analysis activities: Study current system Determine user requirements Recommend solution Acquire hardware and software, if necessary Develop details of system Develop programs, if necessary Install and test new system Train users Convert to new system Conduct post-implementation system review Identify errors and enhancements Monitor system performance

16. Systems Planning and Selection This first phase of the systems development life cycle deals with the process of identifying, selecting, initiating, planning projects and assessing project feasibility. Project Identification and Selection The first step is to identify the need for a system, which can be the result of Problems in existing system or process New feature required in an existing system A new idea for which in Information System is required 16

17. Cont. A requirement to improve efficiency in the organization The need to keep up with competitors During this activity a senior manager, a business group , an Information System manager or a steering committee identifies and assess all possible systems development projects, which are all may yield significant organizational benefits. 3/14/2024 SA-ISB-4-1 17

18. Cont. 18

19. Cont. The need for developing information system can come from three key sources: Managers and business units who want to replace or extend and existing system in order to gain needed information or to provide a new service to customers. Information Systems mangers who want to make a system more efficient, less costly to operate or want to move a system to a new operating environment. Formal planning group that want to improve an existing system in order to help the organization meet its corporate objectives, such as providing better customer service .

20. Cont. The Selection Process may vary in different organizations, but the general process is discussed below. General Process of Identifying and Selection Information Systems development Projects Process of identifying and selection consists of three activities : Identifying potential development projects Classifying and ranking IS development Projects Selecting IS development projects 3/14/2024 SA-ISB-4-1 20

21. Identifying potential development projects This process may be performed by a key member of top management, or a steering committee composed of a cross section managers, or User departments, or the development group Projects identified by top management have a strategic organizational focus , by the steering committees have a cross functional focus , by the individual departments have a narrow, tactical focus . The development group identifies projects based on the ease with existing hardware and systems. Hence, projects may be identified by both top-down and bottom-up initiatives. 3/14/2024

22. Classifying and ranking IS development projects: Done by top managers, a steering committee, business units or the IS development group. The criteria commonly used to evaluate projects are Value chain analysis: Extent to which activities add greatest benefits Strategic alignment: Extent the projects achieves the long term goals

23. Cont. Potential benefits : Extent to which the project helps to improve profits, Customer service, etc. and the duration of the benefits Resource availability: Amount and type of resources required for the project Project size / duration: Number of individuals and duration to complete Technical difficulty / risk: Level of technical difficult to complete. 3/14/2024 SA-ISB-4-1 23

24. Selecting IS development Project: The short and long term projects most likely to achieve the business objectives are considered. The factors must be considered when selecting a project are Perceived needs of the organization Existing systems and ongoing projects Resource availability Current business conditions Perspective of the decision makers The selected project move into the second activity called Project initiation and planning

25. Planning approach Top-down planning Attempts to gain a broad understanding of information system needs of the entire organization and offers: Broader perspective. Improved integration Improved management support Better understanding 3/14/2024 SA-ISB-4-1 25

26. Cont. Bottom-up planning Identifies IS development projects based on solving specific operational business problems or taking advantage of specific opportunities Can be faster and less costly , so may be beneficial in certain circumstances 3/14/2024 SA-ISB-4-1 26

27. Feasibility Study Feasibility is the measure of how beneficial or practical the development of an information system will be to an organization and to the customers Feasibility study: decides whether or not the proposed system is worthwhile It is an assessment of the practically of a proposed project. It is a short focused study that checks

28. Cont. If the system contributes to organizational objectives. If the system can be engineered using current technology and within budget If the system can be integrated with other systems that are used

29. Types of Feasibility study Operational feasibility Cultural feasibility Technical Legal Schedule Economic

30. feasibility: Operational feasibility: is a measure of how well a solution meets the identified system requirements to solve the problems and take advantage of the opportunities envisioned for the system Cultural feasibility: is a measure of how people feel about a solution and how well it will be accepted in a given organization climate 30

31. Technical feasibility is a measure of the practicality of a specific technical solution and the availability of technical resources and expertise to implement and maintain it A process of assessing the development organization's ability to construct a proposed system Schedule feasibility Is a measure of how reasonable the project timetable is Focuses on estimating the start and completion of the project, whether it complies with the schedule and if it deviates out of the schedule

32. Cont. Legal feasibility Is a measure of how well a solution can be implemented within existing legal and contractual obligations Determines whether the proposed system conflicts with legal requirements like any data protection act or any social media law 32

33. Economic feasibility Is a measure of the cost-effectiveness of a project or solution, and involves performing a cost-benefit analysis of an IT investment a process of identifying the financial benefits and costs associated with a development project. Often referred to as a cost-benefit analysis Project is reviewed after each SDLC phase in order to decide whether to continue, redirect, or kill a project

34. 3/14/2024 SA-ISB-4-1 34

35. 3/14/2024 SA-ISB-4-1 35

36. 3/14/2024 SA-ISB-4-1 36

37. 3/14/2024 SA-ISB-4-1 37

38. 3/14/2024 SA-ISB-4-1 38

39. 3/14/2024 SA-ISB-4-1 39

40. 3/14/2024 SA-ISB-4-1 40

41. 3/14/2024 SA-ISB-4-1 41

42. 3/14/2024 SA-ISB-4-1 42

43. Phase 2: Systems Analysis System analysis is the study of a business problem for the purpose of recommending improvements and specifying the business requirements for the solution. It has three parts: determining requirements, structuring requirements and selecting the best alternative design strategy. These steps are may be parallel and repetitive 3/14/2024 SA-ISB-4-1 43

44. 3/14/2024 SA-ISB-4-1 44

45. Traditional Methods for Gathering Requirements The traditional ways to get information directly from those who have the information is by conducting interviews , questionnaires and direct observation . And collecting documentation on the current system and organizational operation in the form of written procedures , forms , reports and other hard copy. All the methods can be used to gather requirements and build up information about the current system. 3/14/2024 SA-ISB-4-1 45

46. Modern methods for gathering requirements The modern methods are additional techniques to collect information about the current system, the organizational area requesting the new system, and what the new system should be like: the modern methods are Joint Application Design and Prototyping. These techniques reduces the time of collecting and structuring the requirements. A more recent approach to system development

47. Systems Analysis and Design in a Changing World, 3rd Edition 47 System Design and development Methodologies Methodologies Comprehensive guidelines to follow for completing every SDLC activity Collection of models, tools , and techniques Models Representation of an important aspect of real world, but not same as real thing Abstraction used to separate out aspect Diagrams and charts Project planning and budgeting aids

48. 48 Computer-Aided Software Engineering: CASE Tools CASE tools is Automated software tools used by systems analysts to develop information systems Automate or support the drawing and analysis of system models and provide for the translation of system models into application programs. A collection of tools used to support the software development process To support or automate activities throughout the systems development life cycle (SDLC)

49. Objective of CASE tools Improve quality of systems to be developed Increase speed of development and design Ease and improve testing process through automated checking Improve integration of development activities via common methodologies Improve quality and completeness of documentation Helps to standardize the development process 3/14/2024 SA-ISB-4-1 49

50. 50 3.3. SDLC Approach Systems development life cycle (SDLC) Provides overall framework for managing system development process Two main approaches to SDLC Traditional approach : structured systems development and information engineering Object-oriented approach : object technologies requires different approach to analysis, design, and programming All projects use some variation of SDLC A more recent approach to system development are Prototyping, Joint Application Design (JAD) and . Spiral Model

51. Prototyping Model Designing and building a scaled-down version of the desired information system with the help of CASE tools Requirements are converted to a working system that is continually revised between an analyst and users One main idea behind prototyping is for the development of fast prototypes and customer availability for feedback . Prototyping is a key tool that supports rapid application development. RAD involves gaining user acceptance of the interface and developing key system capabilities as quickly as possible.

52. Cont. 3/14/2024 SA-ISB-4-1 52

53. 3/14/2024 SA-ISB-4-1 53

54. 3/14/2024 SA-ISB-4-1 54

55. 3/14/2024 SA-ISB-4-1 55

56. Joint Application Design (JAD) A structured process in which users , managers and analysts work together for several days in a series of intensive meetings to specify or review system requirements. These techniques can support effective information collection and structuring while reducing the amount of time required for analysis. Many companies & industries use this technique to study the current system & to determine business requirements

57. Cont. The primary purpose of using JAD in the analysis phase is to collect systems requirements simultaneously from the key people involved with the system The people involved in a JAD are JAD Session Leader, Users, Mangers, Systems Analysts, Scribe, IS staff, sponsor Held in a special room equipped with white boards, audiovisual tools, overhead projector, flip charts and computer generated displays

58. Spiral Model Uses an iterative approach designed to address each phases in development by obtaining customer comments and change, risk analysis, and resolution. The spiral model typically has a ‘spiral’ for each of the traditional development phases. Within a cycle, specific engineering (design, development, etc.) can take place using any other models, like SDLC, prototyping,.. The Spiral Model (Barry Boehm) is a risk-centered development model where each spiral includes major risk activities / assessments. Was developed after SDLC in response to delayed risk in SDLC As the SDLC, it is considered a heavy-weight, plan-driven methodology and is highly structured.

59. The Spiral Model Source : After Boehm 1988 ( © 1988 IEEE) Can see each spiral includes: Planning Risk Analysis / Resolution Engineering activities (design, code, test…) Customer Evaluation (errors, changes, new requirements…)

60. 61 Design Phase What is the design phase ? Acquire hardware and software Develop all details of new or modified information system

61. Design Phase The system analyst converts the description of recommended solution into logical and physical designs Logical design involves in designing the user interface , databases and compute processes, irrespective of the programming languages ( Algorithms , input and output forms, reports, table normalization ) During the Physical design , the analyst team decides the programming language, database systems to be used, hardware platform, operating systems and network environment . 62

62. Cont. The final outcome of the design phase is the physical system specifications , presented in the form such as a diagram or written report ready to be turned over to programmers and other system builders for construction. 3/14/2024 SA-ISB-4-1 63

63. 3/14/2024 SA-ISB-4-1 64 Design Phase What is a detailed design ? Includes several activities Database design Input and output design Program design Detailed design specifications for components in proposed solution Sometimes called physical design

64. 65 Logical and physical Database Design Logical Database Design Process of constructing a model of the data used in an enterprise based on a specific data model (e.g. relational), but independent of a particular DBMS and other physical considerations. Conceptual data model is refined and mapped on to a logical data model. Pearson Education © 2009

65. 66 Physical Database Design Process of producing a description of the database implementation on secondary storage. Describes base relations, file organizations, and indexes used to achieve efficient access to data. Also describes any associated integrity constraints and security measures. Tailored to a specific DBMS system . Pearson Education © 2009

66. Implementation Phase In this phase the information system is coded, tested and installed in the organization, and in which the information system is systematically repaired and improved This phase also includes the initial training to the users and documentation of the system documented throughout the life cycle. During operation part, the problems faced by the users should be solved, and changes and enhancements (new versions) is to be made as per the users’ desire to reflect changing business conditions .

67. Convert to new system Implementation Phase What is the implementation phase ? Purpose is to construct, or build, new or modified system and then deliver it to users Train users Install and test new system Develop programs

68. The Processes of Coding The detailed specifications produced during the design phase are translated into functional (hardware, communications, and executable software.) The design must be translated into a machine-readable form. The code generation step performs this task. Different high level programming languages are used for coding. With respect to the type of application, the right programming language is chosen. Once coding is begun, the testing process can begin and proceed in parallel. As each program module is produced, it can be tested individually, then as a part of a larger program, and then as part of larger system. The deliverables and out come from the coding are the code and program docu mentation.

69. Software testing Software Testing is the process of executing a program or system with the intent of finding errors. or, it involves any activity aimed at evaluating an attribute or capability of a program or system and determining that it meets its required results Although testing is done during implementation, we must plan for testing earlier in the project planning. Testing is more than just debugging. The purpose of testing can be quality assurance, verification and validation , or reliability estimation. 70

70. Cont. Validation (designing the right things) the high-level requirements agreed with the customer, about whether customer’s requirements are satisfied or not. Validation is a much more subjective. Verification(designing the thing right): Verification of a design will most often occur within a single life-cycle activity or between two adjacent activities.eg. the correctness of the algorithm to compute taxes deducted from an employee’s gross income. Testing is an integral part in software development. It is broadly deployed in every phase in the software development cycle. Typically, more than 50% percent of the development time is spent in testing.

71. Software testing can be divided into: Correctness testing, Performance testing, Reliability testing and Security testing. By scope, software testing can be categorized as follows: Unit testing, Integration testing, System testing , Acceptance testing. Unit testing : Each module or unit or component is tested alone in an attempt to discover any errors that may exist in the code. Integration Testing: The process of bringing together all of the modules that a program comprises for testing purposes. 3/14/2024 SA-ISB-4-1 72

72. Subsystem/System Testing The bringing together of all the programs that a system comprises for testing purposes. All results should be documented on the Test Analysis Report, Test Problem Report and on the Test Analysis Approval Determination. Any failed components should be migrated back to the development phase for rework, and the passed components should be migrated ahead for security testing.     3/14/2024 SA-ISB-4-1 73

73. 3/14/2024 SA-ISB-4-1 74 System test What are the three types of tests performed by system developers? Verifies application works with other applications Systems test Integration Test Unit Test Verifies each individual program works by itself Verifies all programs in application work together

74. 3/14/2024 SA-ISB-4-1 75 Implementation Phase What is training? Showing users exactly how they will use new hardware and software in system

75. Implementation Phase What are conversion strategies ? The process of changing old system(manual system) to new system.

76. Direct conversion This is in all or nothing approach The change over is done in one operations. Completely replace the old system with one go E.g. system date setting

77. Phased conversion With this strategy, implementation can be staged with conversion to the new system taking place by degrees. e.g. some new file may be converted and used by employees whilst other file continue to be used on the old system. The new is brought in stage(phase). If each phase is successful then the next phase is started. Eventually, leading to the final phase when the new system fully replaces the old system. 3/14/2024 SA-ISB-4-1 78

78. Pilot conversion With this strategy, the new system replace the old one in one operation but only on small scale. Any errors can be rectified or beneficial changes can be introduced. For example –it might be tried out in one branch of the company or in one location. If successful then the pilot is extended until it eventually replaces the old system completely 3/14/2024 SA-ISB-4-1 79

79. Parallel conversion This is considered the most secured method with both system running in parallel over an introductory period. The old system remains fully operational. While the new system come online. With this strategy both system are used alongside each other, both being able to operate independently. If all goes well the old system is sopped and new system carries on as the only system. 3/14/2024 SA-ISB-4-1 80

80. Evaluation of Information Systems continued……… Three strategies for IS evaluation; Goal based evaluation -explicit goals from origin context Goal free evaluation -no explicit goals are used. Inductive and situational driven strategy Criteria based evaluation -general criteria are used methods of criteria based evaluation of IS are; checklists heuristics, principles/quality ideals Three steps process of IS evaluations are; Intangible benefits evaluation IS investment risk analysis Tangible benefits evaluation 81