V-LRN� VIRTUAL LEARNING NETWORK

Block – 4

Unit - 14

System Analysis and Design

Information Systems For Managers

Topics to be covered

14.1 Introduction

14.2 Traditional Systems Life Cycles

14.2.1 Initiation

14.2.2 Development

14.2.3 Implementation

14.2.4 Operations and Maintenance

14.3 Systems Life Cycle

14.3.1 Stages of the Systems Life Cycle

14.4 Systems Analysis

Topics to be covered (Contd.)

14.5 Systems Design

14.5.1 Logical and Physical Design

14.6 Implementation and Maintenance

14.6.1 Programming

14.6.2 Testing

14.6.3 Conversion

14.6.4 Production and Maintenance

14.7 Summary

Introduction

• The software is said to have a life cycle composed of several phases. Each of these phases results in the development of either a part of the system or something associated with the system, such as a test plan or a user

manual.

• In the traditional life cycle model, each phase has well-defined starting and ending points, with clearly identifiable deliverables to the next phase.

Traditional System Life Cycle

• The goal of the traditional system life cycle is to keep the project under control and assure that the information system produced, satisfies the requirements.
• The traditional system life cycle divides the project into a series of steps, each of which has distinct deliverables, such as documents or computer programs. This is known as the systems development life cycle (SDLC).

Traditional System Life Cycle (Contd.)

Traditional System Life Cycle (Contd.)

• Many versions of the traditional system life cycle emphasize the building or software and de-emphasize what happens in the organization before and after software development. Because this unit is directed at business professionals, its version of the
• Traditional system life cycle emphasizes implementation and operation in the organization in addition to software development. It keep the project under control and assure that the information system produced, satisfies the requirements.

• The initiation phase may begin in many different ways. A user may work with the IS staff to produce a written request to study a particular business problem.
• A top manager may notice a business problem and ask the head of IS to look into it. A computer crash or other operational problem may reveal a major problem that requires a larger project to fix it completely.
• Its goal is to analyze the scope and feasibility of a proposed system and to develop a project plan.

Initiation

Initiation (Contd.)

• The feasibility study is a user-oriented overview of the proposed information system’s

purpose and feasibility. A system’s feasibility is

typically considered from economic,

technical, and organizational viewpoints.

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Development

• The development phase creates computer programs and involves processing described in the functional specification.
• This is done through a process of successive refinement in which the functional requirements are translated into computer programs and hardware requirements.
• This phase begins with implementation planning, the process of creating plans for training, conversion and acceptance testing.

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• The operation and maintenance phase starts after the users have accepted the new system. This phase can be divided into two activities-

(A) ongoing operation and support,

(B) Maintenance.

• These steps continue throughout the system’s useful life. The end of a system’s life cycle is its absorption into another system.
• Ongoing operation and support is the process of ensuring that the technical system components continue to operate correctly & effectively.

Operations and Maintenance

Operations and Maintenance (Contd.)

Operations and Maintenance (Contd.)

Operations and Maintenance (Contd.)

Operations and Maintenance (Contd.)

Operations and Maintenance (Contd.)

System Life Cycle

• The system life cycle methodology assumes that an information system has a life cycle similar to that of any living organism. Phases of SDLC includes
• Project identification and selection
• Project initiation and planning
• Analysis
• Logical design (concentrates on business aspects of the system in theoretically way )
• Physical design (Language / DBMS /file structure / technology / tools to be used)
• Implementation
• Testing

Systems Analysis

• Systems analysis is the analysis of the problem that the organization will try to solve with an information system. It consists of defining the problem, identifying its causes, specifying the solution and identifying the information requirements that must be met by a system solution.
• It also involves a feasibility study to determine whether that solution is feasible or not within provided resources and constraints at technical, economic & organizational level.

Systems Analysis (Contd.)

• Normally the systems analysis process will identify several alternative solutions that can be pursued by the organization. The process will then assess the feasibility of each. Three basic solution alternatives exist for every systems problem-

1. To do nothing, leaving the existing

situation unchanged

2. To do modify or enhance existing systems

3. To develop a new system

Systems Analysis (Contd.)

• Establishing Information Requirements is the

most difficult task of the systems analyst is

to define the specific information requirements

that must be met by the system solution selected.

• At the most basic level, the information

requirements of a new system involve identifying

who needs what information, where, when and

how. Requirements must consider economic,

technical, and time constraints, as well as the

goals, procedures, and decision processes of

the organization.

Systems Design

• Systems design has three objectives-
• First, the systems designer is responsible for considering alternative technology configurations for carrying out and developing the system as described by the analyst.
• Second, designers are responsible for the management and control of the technical

realization of systems.

• Third, the systems designer details the system specifications that will deliver the functions identified during systems analysis.

Logical & Physical Design

• The design for an information system can be broken down into logical and physical design specifications.
• Logical design lays out the components of the system and their relationship to each other, as they would appear to users.
• It showed what the system solution would do as opposed to how it is actually implemented physically.
• It describes inputs and outputs, processing functions to be performed.

Logical & Physical Design

(Contd.)

• Design alternative is an on-line system featuring more timely information & reduced manual effort, but at greater cost for computer processing, software, and security and recovery procedures required to maintain the integrity of the product.
• Technical specialists cannot direct information systems design alone. It demands a very high level of participation and control by end users.

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Implementation And Maintenance

• The remaining steps in the systems development process translate the solution specifications established during systems analysis and design into a fully operational information system. These concluding steps consist of programming, testing, conversion, and production and maintenance.
• The process of translating design specifications into software for the computer constitutes a smaller portion of the systems development cycle than design and perhaps the testing activities.

Programming

• Programming is the heart of the system as it takes the shape of a concept.
• During the programming stage, system specifications that were prepared during the design stage are translated into program code.
• On the basis of detailed design documents for files, transaction and report layouts & other design details, specifications for each program in the system are prepared.

Testing

• Testing is the process of executing a software again and again with the intent of finding the errors .
• Test data must be carefully prepared, results reviewed and corrections made in the system. Unit testing or program testing consists of testing each program separately in the

system.

• Acceptance testing provides the final certification that the system is ready to be used in a production setting. Systems tests are evaluated by users and reviewed by mgmt.

Conversion

• Conversion is the process of changing from the old system to the new system.
• It answers the question, “ Will the new system work under real conditions”.
• Four main conversion strategies can be employed , the parallel strategy, direct cutover strategy, pilot study strategy and phased approach strategy

Production and Maintenance

• After the new system is installed and conversion is complete, the system is said to be in production.
• During this stage, both users and technical specialists determine how well it has met its original objectives and to decide whether any revisions or modifications are in order will review the system.
• Changes in hardware, software, documentation, or improve processing efficiency are termed maintenance.

Summary

• There is a fundamental dilemma faced by anyone developing a computer application. Most problems are so large they have to be split into smaller pieces.
• The difficulty lies in combining the pieces back into a complete solution. Often each piece is assigned to a different team, and sometimes it takes months to complete each section. Without a solid plan and control, the entire system might collapse.

Summary (Contd.)

• Thousands of system development projects have failed or been cancelled because of these complications.
• Partly because of the problems that have been encountered in the past and partly because of technological improvements, several techniques are available to develop computer systems.
• The most formal approach is known as the systems development life cycle.