Chapter 1Introduction To Information System Analysis & Design

1.1 Introduction to System Analysis And Design

1.2 The Analyst’s and Accountants Role in System Development

1.3 Evolutions of Systems Development Methodologies

1.4 Iterative and Incremental Development

Outline:

1.1 Introduction to

System Analysis And

Design

The major goal of SAD is to improve organizational system.

Process of improving organizational system involves developing or acquiring application software and training employees to use it.

Application Software is designed to support a specific organizational function or process, such as inventory management, payroll, or market analysis. For an example, spreadsheets, word processors, and database management systems.

Main goal of application software is to turn data into information

Example:

“ A software developed for the inventory department at a bookstore may keep track of the number of books in stock of the latest best seller.”

“A software for the payroll department may keep track of the changing pay rates of employees.”

1.2 The Analyst’s and Accountants Role in

System Development

SYSTEM

• A system is an interrelated set of business procedures

used within one business unit working together for a

purpose.• Consist of nine characteristics• Exist within an environment.• A boundary separates a system from its environment.

CHARACTERISTICS OF A

SYSTEM• Components.• Interrelated Components.

• Bondary.• Purpose.

• Environment.• Interfaces.• Constraits.• Input.• Output.

IMPORTANT SYSTEM CONCEPTSDECOMPOSITION.

• The process of breaking down a system into smaller components.• Allows the system analyst to:

i) Break a system into a small, manageable and understandable subsystem.

ii) Focus on one area at a time without interference from other areas.

iii) Concentrate on a component pertinent to one group of users without confusing users with unnecessary details.

iv) Build different components at independent times and have the help of different analyst.

MODULARITY.

• Process of dividing a system into modules of a relatively uniform size.

• Modules simplify system design.

COUPLING

• Subsystems that are dependent upon each other are coupled.

COHESION• Extend to which a subsystem performs a single

function.

SYSTEM ANALYST

• IT professional who specializes in analyzing, designing and

implementing information system.

• Assess the suitability of information systems.

• Analysis and design techniques to solve business problems using

information technology.

• Plan, develop, and maintain information systems

• Manages IT projects, including tasks, resources, schedules, and costs

• Conducts meetings, delivers presentations, and writes memos,

reports, and documentation

A Modern Approach to System

Analysis and

DesignSYSTEM INTEGRATION

Allows hardware and software from different vendors to work together.

Enables procedural language systems to work with visual programming systems.

Visual programming environment uses client/server model.

ROLE IN SYSTEM DEVELOPMENT

• Study problems and needs of an organization.

• Determine the best approach to improving organization through the use of people, methods and information system.

• Develop four types of skill which is analytical, technical, managerial and interpersonal.

• Help system users and managers define their requirements for new or enhanced information systems.

1.3 Evolutions of System

Development Methodologies

System Development Methodology??

A standard process followed in an organization to conduct all the steps necessary to analyse, design, implement, and maintain information systems.

Systems Development Life Cycle ( SDLC)

A common methodology used in an organization

It marks the phases or steps of information systems development

System Planning & Selection

System Analysis

System Design

System Implementa

tion & Operation

Phase 1:System Planning & Selection

System Planning & Selection

• Identify the needs for a new or enhance existing system

• To investigate the system and determine the propose system’s scope

A feasibility study is conducted before the second phases of the SDLC to determine the economic and organizational impact of the system.

Phase 2

System AnalysisDetermine the requirements of the

system

Determine what the users want from a proposed system

Study the requirements and

structure them according to their interrelationships, eliminating any redundancies.Compare the

alternatives to determine which best

meet the requirements.

Examples: cost &labor

Output( The Best

Alternative)

Phase 3 System Design

Logical Design

Physical 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 modelling.• It concentrates how the system will impact the functional units within

the organization.

•The physical design relates to the actual input and output processes of the system.

Logical Design

Physical Design

Implementation

Operation

System Implementation

& Operation

Phase 4

Implementation

• It includes coding, testing and installation• Coding --- write the programs that make up the system• Testing--- test individual programs & the entire system in order to find and correct errors.• Installation--- the new system becomes a part of the daily activities of the organization

• It also included initial user support such as the finalization of documentation, training programs and ongoing user assistance.

Operation

• Users sometimes found problems with how the system works and will offen think of improvements

• Programmers make the changes that uses ask for and modify the system to reflect changing business condition

• These changes are necessary to keep the system running and useful.

1.4Iterative and Incremental

Development

ALTERNATIVE APPROACHES TO DEVELOPMENT

• Prototyping• Rapid Application Design (RAD)• Computer-Assisted Software Engineering (CASE) tools• Joint Application Design (JAD)• Participatory Design (PD)• Agile Methodologies

PROTOTYPING

• Building a scaled-down working version of the system

• Advantages: - users are involved in design - captures requirements in concrete form

Rapid Application Design (RAD)

• Utilizes prototyping to delay producing system design until after user requirements are clear

• Systems development methodology created to radically decrease the time needed to design and implement information systems

Computer-Assisted Software Engineering (CASE) Tools

• Automated software tools used by systems analysts to develop information systems

• Can be used throughout SDLC• Product and tool integration is provided through a

repository

Joint Application Design (JAD)

• Users, managers and analysts work together for several days

• System requirements are reviewed• Structured meetings

Participatory Design (PD)

• Emphasizes role of the user• Entire user community can be involved in

design

Agile Methodology

• Focuses on:

- adaptive methodologies

- people instead of roles

- self-adaptive development process

End of the Chapter