ISM-U3-WP

Unit III (12 Hours) Systems Design and Development Methodologies 1. Foundation Concepts 2. Approaches to Designing and Building Systems: SDLC Approach, Prototyping, Spiral Method, End User Development. First Online Test 3. Logical and Physical Design, 4. Evaluation of Information Systems. Second Online Test: 

1 Unit III (12 Hours) Systems Design and Development Methodologies 1. Foundation Concepts 2. Approaches to Designing and Building Systems: SDLC Approach, Prototyping, Spiral Method, End User Development. First Online Test 3. Logical and Physical Design, 4. Evaluation of Information Systems. Second Online Test

Introduction : 

2 Introduction Information Systems Analysis and Design Complex process whereby computerbased information systems are developed and maintained Application Software Result of systems analysis and design Designed to support specific organizational functions or processes

Slide 3: 

3 Software engineering processes have been developed to assist in analysis and design Methodologies Comprehensive, multi-step approaches to systems development Techniques Processes that are followed to ensure that work is well thought out, complete and comprehensible to others on the project team Tools Computer programs to assist in application of techniques to the analysis and design process

Slide 4: 

4 Information Systems Analysis and Design A method used by companies to create and maintain systems that perform basic business Functions Main goal is to improve employee efficiency by applying software solutions to key business tasks A structured approach must be used in order to ensure success .

Slide 5: 

5 The process of designing, building, and maintaining information systems The individual who performs this task is called Systems analyst Organization wants to hire System analyst because they have both technical and managerial expertise.

Herbert A Simon Decision Making Model: 

6 Herbert A Simon Decision Making Model Herbert A. Simon developed a model of decision making. The model consisted of three steps, intelligence, design, and choice. In the intelligence phase, the problem is identified, and information is collected concerning the problem. This can be a long process, as the decision to be made comes from the information. The design phase develops several possible solutions for the problem. Finally, the choice phase chooses the solution. 1. The Intelligence Phase The intelligence phase consists of finding, identifying, and formulating the problem or situation that calls for a decision.  This has been called deciding what to decide .  The intelligence stage may involve, for example, comparing the current status of a project or process with its plan.  The end result of the intelligence phase is a decision statement.

Slide 7: 

7 2. The Design Phase The design phase is where we develop alternatives.  This phase may involve a great deal of research into the available options.  During the design phase we should also state our objectives for the decision we are to make. 3. The Choice Phase In the choice phase, we evaluate the alternatives that we developed in the design phase and choose one of them.  The end product of this phase is a decision that we can carry out.

Slide 8: 

8 Extensions to Simon's Model 4. Implementation The decision that is ultimately carried out. 5. Review In this phase, decision implemented is evaluated. Was the course of action taken a good choice?

How does Simon’s Model correspond to the Scientific Method and to the Systems Development Life Cycle ? : 

9 How does Simon’s Model correspond to the Scientific Method and to the Systems Development Life Cycle ? SIMON'S MODEL SCIENTIFIC APPROACH SDLC APPROACH Intelligence Define Problem System Investigation Design Develop Alternatives System Analysis Choice Select Solution / System Design Design Solution Implementation Implement Solution Implementation Review Maintenance

Approaches to Designing and Building Systems: 

10 Approaches to Designing and Building Systems SDLC Prototyping/Iterative method Spiral method End User Development Incremental method Joint Application Design (JAD) Rapid Application Development (RAD)

1. Systems Development Life Cycle (SDLC) Approach: 

11 1. Systems Development Life Cycle (SDLC) Approach Series of steps used to manage the phases of development for an information system Consists of five phases: System Investigation: Project Identification, Selection and Planning Analysis Design Implementation Maintenance

Phases of the Systems Development Life Cycle: 

12 Phases of the Systems Development Life Cycle Project Identification, Selection and Planning: Undertake only those projects critical to mission, goals, and objectives Select a development project from all possible projects that could be performed Different evaluation criteria used to rank potential projects Helps organization to determine whether or not resources should be dedicated to a project. It involves following activities Identification of need Prioritization and translation of need into a development Schedule Formal preliminary investigation of the problem at hand Presentation of reasons why system should or should not be developed by the organization

Slide 13: 

13 2. Analysis: It involves study of current procedures and information systems Determine requirements Study current system Structure requirements and eliminate redundancies Generate alternative designs Compare alternatives Recommend best alternative 3. Design: Logical Design Concentrates on business aspects of the system Physical Design Concentrates on Technical specifications

Slide 14: 

14 4. Implementation: Hardware and software installation Programming User Training Documentation 5. Maintenance: System changed to reflect changing conditions System obsolescence Maintenance types: Corrective maintenance Adaptive maintenance Perfective maintenance Preventive maintenance

Steps in the Systems Development Process : 

15 Steps in the Systems Development Process

Slide 16: 

16

Other Approaches to IS Development: 

17 Other Approaches to IS Development 2.Prototyping: To avoid the potential problem of a system being incompatible with the system user, many systems analysts have advocated prototyping.   In prototyping , the focus is on developing a small model, or prototype, of the overall system instead of developing the entire system before users ever lay their hands on it.  Users work with the prototype and suggest modifications, and then the prototype is enhanced.  As soon as the prototype is refined to the point where upper management feels confident that a larger version of the system will succeed, either the prototype can be expanded into the final system or the organization can move ahead with the remaining steps of the system development process. In prototyping, analysis and design generally proceed together in small steps that finally result in a completed system. Building a scaled-down working version of the system Advantages: Users are involved in design Captures requirements in concrete form

Slide 18: 

18 Prototyping Approach

Slide 19: 

19 3.Rapid Application Development (RAD): Utilizes prototyping to delay producing system design until after user requirements are clear 4. Joint Application Design (JAD): Users, Managers and Analysts work together for several days System requirements are reviewed Structured meetings 5.End-User Development End-user development is a system development effort in which the user is primarily responsible for the development of the system.  This is in contrast to the other types of development discussed here, in which a qualified computer professional, such as a systems analyst, takes charge of the system development process .

Slide 20: 

20 As you might guess, end-user development is feasible only when the system being developed is relatively small and inexpensive.  A good example is when a user purchases a PC and develops applications on his or her own.  In developing the system, the user might follow a prototyping approach or a method similar to the traditional system development approach. Certain dangers exist when users develop their own systems in a business environment.  Among these are users who do not incorporate proper security measures in their systems, who create systems that interfere with other systems within the organization, and who build systems that cannot effectively be supported.  Nonetheless, when computer professionals within an organization are too overloaded to build small important systems to help users, end-user development may be the only alternative.

6. Evolutionary or spiral methodology: : 

21 6. Evolutionary or spiral methodology: The work never gets done! Different versions, always in different stages. The spiral model is a software development process combining elements of both design and prototyping -in-stages, in an effort to combine advantages of top-down and bottom-up concepts. Also known as the spiral lifecycle model (or spiral development), it is a systems development method (SDM) used in information technology (IT). This model of development combines the features of the prototyping model and the waterfall model . The spiral model is intended for large, expensive and complicated projects.

Slide 22: 

22 Spiral Approach

Logical And Physical Design: 

23 Logical And Physical Design Systems design is the process of defining the architecture, components, modules, interfaces, and data for a system to satisfy specified requirements . Logical design The logical design of a system pertains to an abstract representation of the data flows, inputs and outputs of the system. This is often conducted via modeling, using an over-abstract (and sometimes graphical) model of the actual system. In the context of systems design are included. Physical design The physical design relates to the actual input and output processes of the system. This is laid down in terms of how data is input into a system, how it is verified/authenticated, how it is processed, and how it is displayed as output.

Slide 24: 

24 Physical design, in this context, does not refer to the tangible physical design of an information system. To use an analogy, a personal computer's physical design involves input via a keyboard, processing within the CPU, and output via a monitor, printer, etc. It would not concern the actual layout of the tangible hardware, which for a PC would be a monitor, CPU, motherboard, hard drive, modems, video/graphics cards, USB slots, etc. it involve detail design of user and a product database structure processing and control processor .The H/S personal specification a develop for the proposed system .

Evaluation Of Information Systems: 

25 Evaluation Of Information Systems The adoption of Information Technology (IT) and Information Systems (IS) represents significant financial investments, with alternative perspectives to the evaluation domain coming from both the public and private sectors. As a result of increasing IT/IS budgets and their growing significance within the development of an organizational infrastructure, the evaluation and performance measurement of new technology remains a perennial issue for management. Evaluating Information Systems explores the concept of evaluation as an evolutionary and dynamic process that takes into account the ability of enterprise technologies to integrate information systems within and between organizations. In particular, when set against a backdrop of organizational learning. It examines the changing portfolio of benefits, costs and risks associated with the adoption and diffusion of technology in today's global marketplace

Slide 26: 

26 Within organizations, information systems evaluation is a key part of IS investment decisions, for example in deciding whether to go ahead with a particular project, or to modify or scrap a development. The evaluation becomes a basis for comparison with other projects, both inside and outside the organization. With increasingly large investments, these become decisions with significant financial implications. Moreover, such decisions can have significant implications for both groups and individuals within the organization. People’s careers or working lives, or a group’s command of resources or status, may be contingent on the evaluation of a particular information system. An evaluation is normally a form of measurement or classification, a type of inscription that translates a particular entity or situation, such as an IT investment, into a quantifiable outcome against certain criteria

Slide 27: 

27 investment analysis, Financial implications (Cost-Benefit identification) attempts to evaluate whether an IS investment is likely to be worthwhile financially impact analysis, looking at the effect a new system has had - or is likely to have - on a particular group or organizational function performance measurement, focusing on how well a particular system is working, typically using fairly low-level technical or financial metrics problem diagnosis, seeking to account for, and solve, a particular IS problem risk assessment, examining the risks of projects failing in some way, and portfolio optimization, where an organization wishes to maximize its portfolio of projects, rather than judging individual projects

Slide 28: 

28 Evaluation occurs twice in the 'traditional' structured systems analysis and design approach: first, in the feasibility phase, in which an attempt is made to establish likely impact and costs, and, second, in the form of a post-implementation evaluation, which is an attempt to measure what impact the system actually had. This approach focuses on issues such as whether the project was delivered on time, whether it was to budget and whether it met the specifications, and ignores other issues, such as what the stakeholders think of both the 'process' and the 'product' .Post-implementation evaluation is also criticized on the grounds that it is generally conducted by system developers as a quick 'pack up and get out' project closure activity. Broader studies, based on theories of information economics, examine the value of IS development on organizations based on factors such as strategic impact, productivity impact and consumer value, while another set of studies, based on behavioral science, addresses the relationship between IS development and individual satisfaction and decision-making behavior, and the consequent impact on the organization.

Slide 29: 

29