chapter01 - esssentials of systems analysis and design

8/3/2019 Chapter01 - Esssentials of Systems Analysis and Design

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Systems Theory and Design

MAN 5835

Dr. Suarez-Brown


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The Systems Development

Environment

1.11.1

Chapter 1


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Learning Objectives

Define information systems analysis

and design

Discuss the modern approach to

systems analysis and design

Describe the organizational roles

involved in information systemsdevelopment

1

.21

.2


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Learning Objectives

Describe four types of informationsystems:

Transaction Processing Systems (TPS)Management Information Systems (MIS)

Decision Support Systems (DSS)

Expert Systems (ES)

Describe the information systemsdevelopment life cycle (SDLC)

1.31.3


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Learning Objectives

Discuss alternatives to the systems

development life cycle

Discuss the role of computer-aided

software engineering (CASE) tools in

systems development

1.41.4


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Introduction

Information Systems Analysis and Design Complex process whereby computer-based

information systems are developed andmaintained

Driven from an organizational prospective Process of creating, producing, and supporting the

organizations products and services

Based on:

Understanding of organizations objectives,

Structure,

Processes,

Knowledge of how to exploit information technology foradvantage

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Introduction

Application Software

Result of systems analysis and design

Designed to support specific organizational

functions or processes

Inventory management, payroll, or market

analysis

Total information system

What is an information system?


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IntroductionInformation System Set of interrelated components that collect (or

retrieve), process, store, and distribute informationto support decision making, coordination and

control in an organization Hardware

Software

Documentation

Training Materials Job Roles associated with overall system

Controls

People

What are its functions?


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Information System

INPUT OUTPUTPROCESS

FEEDBACK

STORAGE


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Introduction

Software engineering processes have beendeveloped to assist in analysis and design

Developed work methods to become adisciplined process Methodologies

Comprehensive, multi-step approaches to systemsdevelopment

Consistent with general management style Incorporate several development techniques

Techniques Processes that are followed to ensure that work is well

thought-out, complete and comprehensible to others on

the project team1.61.6


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Introduction

Tools Computer programs to assist in application of techniques

to the analysis and design process

Tools and techniques must be consistent with anorganizations systems development methodology

Systems Analyst The organizational role most responsible for the

analysis and design of information systems Study the problems and needs of an organization

in order to determine how people, methods, andinformation technology can best be combined tobring about improvement in the organization


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Introduction

Information Systems Analysis and Design

Began in the 1950s

A method used by companies to create andmaintain 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

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Introduction

Systems Analyst performs analysis and

design based upon:

Understanding of organizations objectives,structure and processes

Knowledge of how to exploit information

technology for advantage

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Software Engineering Process

A process used to create an informationsystem

Consists of (three elements):

1.111.11

MethodologiesA sequence of step-by-step approaches that helpdevelop the information system

TechniquesProcesses that the analyst follows to ensure thorough,complete and comprehensive analysis and design

ToolsComputer programs that aid in applying techniques


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Data and Processes

Three key components of an

information system

Data Data Flows

Processing Logic

Data vs. Information?

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DataRaw facts

InformationDerived from data

Organized in a manner that humans canunderstand


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Data and Processes

Data

Understanding the source and use of data

is key to good system design

Various techniques are used to describe

data and the relationship amongst data

Data Flows Groups of data that move and flow through

the system

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Data and Processes

Data Flows (Continued)

Include description of sources and

destination for each data flow

Processing Logic

Describe steps that transform data and

events that trigger the steps

1.171.17


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Data, Data Flow, and

Processing Logic


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Approaches to Systems

Development

Process-Oriented Approach Focus is on flow, use and transformation of data in

an information system

Involves creating graphical representations suchas data flow diagrams and charts

Data are tracked from sources, throughintermediate steps and to final destinations

Natural structure of data is not specified

Disadvantage: data files are tied to specificapplications

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Focuses on what the systems is supposed to doFocuses on what the systems is supposed to do

Less stableLess stable -- business processes constantly changingbusiness processes constantly changing


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Approaches to Systems

Development

Data-Oriented Approach

Depicts ideal organization of data,

independent of where and how data areused

Data model describes kinds of data and

business relationships among the data

Business rules depict how organizationcaptures and processes the data

1.201.20

Focuses on the data the system needs to operateFocuses on the data the system needs to operate

Data redundancy controlled; data files designedData redundancy controlled; data files designed

for whole enterprisefor whole enterprise


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Traditional Relationship

between Data and Applications

Traditional Approach

Database Approach


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Key Differences


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Databases and Application

Independence

Shared collection of logically related data

Organized to facilitate capture, storage andretrieval by multiple users

Centrally managed

Designed around subjects Customers

Suppliers

Application Independence Separation of data and definition of data from

applications

1.231.23

Database


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Organizational Responsibilities

in Systems DevelopmentSystems Analysts work in teams Project Based Includes

IS Manager Programmers

Users Other specialists

Characteristics of Successful Teams

1.241.24

Diversity of backgrounds

Tolerance of diversity

Clear and complete communication

Trust

Mutual Respect

Reward structure that promotes shared responsibility


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Organizational Responsibilities in

Systems Development

IS Manager

May have a direct role in systems

development if the project is small Typically involved in allocating resources to

and overseeing system developmentprojects.

Systems Analyst Key individuals in the systems

development process


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Systems Development

Skills of a Successful Systems Analyst Analytical

Understanding of organizations, functions, identifyopportunities and problems, analyze and solve problems

Problem solving skills System thinking

Ability to see organizations and information systems assystems

View important relationships among IS, organization theyexist in, and the environment in which the organizations exist

Technical Understanding of potential and limitations of technology

Guide the systems design and development

Work with Programming languages, Operating Systems(OS), and computer Hardware (HW) platforms

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Systems Development

Management

Ability to manage projects, resources, risk and

change Interpersonal

Effective written and oral communication skills

Work with end-users, other analysts and

programmersMajor role as a liaison among users


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Systems Development

Programmers Convert specifications into instructions that the

computer understands

Write documentation and testing programs Structured Programming

All computing instructions represented through threestructures:

Sequence, repetition, and selection

Code generators,

Computer-Aided Software Engineering(CASE)

Business Managers Have power to fund projects and allocate resources

Set general requirements and constraints for projects1.281.28


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Systems Development

Other IS Managers/Technicians Database Administrator

Involved in design, development and maintenance of

databases

Network and telecommunications experts Develop systems involving data and/or voice

communications

Human Factors Specialists Involved in training users and writing documentation

Internal Auditors Ensure that required controls are built into the system

Keeping track of changes in the systems design

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TYPES OF INFORMATION SYSTEMSTYPES OF INFORMATION SYSTEMS

DATA WORKERSDATA WORKERS

KIND OF SYSTEM GROUPS SERVEDKIND OF SYSTEM GROUPS SERVED

STRATEGIC LEVEL SENIORSTRATEGIC LEVEL SENIOR

MANAGERSMANAGERS

MANAGEMENT LEVEL MIDDLEMANAGEMENT LEVEL MIDDLEMANAGERSMANAGERS

OPERATIONALOPERATIONAL OPERATIONALOPERATIONAL

LEVEL MANAGERSLEVEL MANAGERS

KNOWLEDGE LEVEL KNOWLEDGE &KNOWLEDGE LEVEL KNOWLEDGE &

SALES & MANUFACTURING FINANCE ACCOUNTING HUMANSALES & MANUFACTURING FINANCE ACCOUNTING HUMAN

RESOURCESRESOURCESMARKETINGMARKETING


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Systems Development for

Different IS Types

Table 1-3 pg 17 3rd edition of Systems

Analysis and Design

Discusses IS Characteristics and System

Development Methods for all four IS

Types


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Types of Information Systems

and Systems DevelopmentTransaction Processing Systems (TPS) Automate and support handling of data about

elementary organizational business activities(transactions)

Systems answer routine questions and track the flowand processing of transactions through theorganization

i.e. systems to record bank deposits, customer orderprocessing, employee timekeeping, scheduling

Goal:

Improve transaction processing (speed)

Use fewer people

Improve efficiency and accuracy

Integration1.321.32


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and Systems Development

Management Information Systems (MIS) Converts raw data from transaction processing

system into meaningful form

Provide managers with reports or with on-lineaccess to the organization

Provide Periodic reports or summaries of data

Often required data from several TPS

i.e. relocation control systems Quarterly or Bi-Annual Reports

Aggregate and Summarize data

Understand relationships between data to ultimately

be summarized


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MISMIS

MIS FILESMIS FILES

SALES

DATA

UNIT

PRODUCT

COST

PRODUCT

CHANGE

DATA

EXPENSE

DATA

MISREPORTS

MANAGERSMANAGERS

TPS

OrderProcessing

System

Materials Resource

Planning System

General LedgerSystem

ORDER FILE

PRODUCTION MASTER FILE

ACCOUNTING FILES

TPS DATA FOR MIS APPLICATIONS

Total amount of particular item used this quarter

Compare total annual sales figures for specific products to planned targets


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and Systems DevelopmentDecision Support Systems (DSS)

Designed to help decision makers

Provides interactive environment for decision making

Use internal information from TPS and MIS as well as externalsources

Composed of a database (extracted from TPS or MIS)mathematical or graphical models (model base) and an userinterface

Have more analytical power than other systems

Less structured and used to support a certain scope of decision-making activities

EIS serves the management level of the organization Estimating Systems, financial calculations (given certain

parameters)

inventories of information assets (including legacy and relational data

sources, cubes, data warehouses, and data marts),

comparative sales figures between one period and the next,

projected revenue figures based on product sales assumptions

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and Systems Development

Expert Systems (ES) Replicates decision making process

Attempts to codify and manipulate knowledge rather thaninformation (If-then-else rules used within a specific

domain of problems) Knowledge representation describes the way an expert

would approach the problem

Interactive dialogue: ES asks questions, user suppliesanswers, answers used to determine which rules applyand then ES provides a recommendation based on rules

Help senior management tackle and address strategicissues and long-term trends, both in the firm andexternal environment

Where will employment levels be in ten years?, etc.

What is the five year operating plan?


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Systems Development Life

CycleSystem Development Methodology Orderly set of activities conducted and planning for each

development project

Standard process followed in an organization

Consists of:

Project Identification and selection Project Initiation and planning

Analysis

Design

Implementation

Maintenance

Life Cycle can be:

Parallel: complete some activities in one phase along with somein another phase

Iterative: phases are repeated as required until acceptable

Spiral: constantly cycle through phases at different levels of detail

Circular: end of useful life of one system leads to the beginning ofanother project

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Cycle

Series of steps used to manage the phases of

development for an information system

Consists of six phases: Project Identification and Selection

Project Initiation and Planning

Analysis

Design

Implementation

Maintenance

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Cycle

Phases are not necessarily sequential

Each phase has a specific outcome and

deliverable Individual companies use customized life

cycles

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Phases of the Systems

Development Life CycleProject Identification and Selection Two Main Activities

Identification of need

Prioritization and translation of need into a development

schedule Helps organization to determine whether or not

resources should be dedicated to a project.

Project Initiation and Planning Two Activities

Formal preliminary investigation of the problem at hand Presentation of reasons why system should or should not

be developed by the organization

Produce a specific plan for the proposed project

the team will follow using the remaining SDLC steps

Customizes the standard SDLC

Specifies time and resources needed

1.401.40

Baseline Project Plan

Develop system to solve problem


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Cycle

Analysis Study of current procedures and information

systems used to perform organizational tasks

Determine requirements Determine what users want from proposed system

Study current system

Structure requirements and eliminate redundancies

Generate alternative designs to match requirements

Compare alternatives and determine which best meetsthe requirements within limits (cost, labor, technicallevels)

Recommend best alternative

Make plans to acquire HW/SW necessary to build oroperate system as proposed1.411.41


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CycleDesign Devoted to designing the new or enhanced system

Convert description or solution into logical and thenphysical systems specifications

Logical Design Concentrates on business aspects of the system its

functions (high level of specification)

Independent of any specific HW/SW platform

Physical Design Technical specifications

Design various parts of system to perform the physicaloperations necessary to facilitate data capture, processing,and information output

Determine physical details necessary to build final system

Final product: physical system specifications ready to beturned over to programmers and other systems builders forconstruction

1.421.42


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CycleImplementation Turn systems specifications into working system

that is tested and then put into use

Coding, testing and installation

Programming User Training

Documentation (produced throughout the life cycle)

Hardware and software installation

Maintenance Information systems is systematically repaired and

improved Users find problems often think of better ways to

perform functions

System changed to reflect changing conditions

System obsolescence (change over time)


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Cycle

Highly linked set of phases whose products feed the activities in subsequent phases

Must be carefully planned and managed


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Traditional SDLC

Several Criticisms The way the life-cycle is organized

Analyst must freeze design at a particular point and thengo forward (milestones) difficult to go back

Changing business conditions Enormous time and effort; very expensive to make

changes once developed

Tends to focus too little time on good analysis anddesign

Does not match users needs Requires extensive maintenance

Increases development costs

Maintenance costs account for 40% to 70% of systemdevelopment costs


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Structured Analysis and

Structure DesignEarly 1970s

To address traditional SDLC problems

Even more disciplined similar to

engineering fields Tools: Data Flow Diagrams

Transform Analysis

Improve the analysis and design phases

Reduce maintenance time and effort Easier to go back to earlier phases in life cycle when

necessary (for when requirements change)

Emphasis on partitioning/dividing problem into smaller,more manageable units

Clear distinction between physical and logical design


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Object-Oriented Analysis and

DesignOOAD third approach to systemsdevelopment

Combines data andprocesses (calledmethods) into single entities called objects

Limited number of operations for any givendata structure

Make system elements more reusable

Inheritance: organized into object classes Groups of objects share structural and behavioral

characteristics (person, customer)

Primary tasks: Identifying objects, defining their structure and

behavior, and defining their relationship


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Approaches to Improving

Development

Rapid Application Development (RAD) Delay producing system design until after user requirements are

clear

Prototyping serves as the working description of needs

Gaining user acceptance Sacrificing computer efficiency for gains in human efficiency in

rapidly building and rebuilding working systems

Prototyping (form of RAD) Building a scaled-down functional version of the system

Advantages:

Users are involved in design Provides feedback

Captures requirements in concrete form

Stand-alone or used to augment the SDLC

1.481.48


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Approaches to Development

Joint Application Design (JAD)

New process for collecting information

system requirements and reviewing systemdesigns

Users, Managers and Analysts work together

for several days

System requirements are reviewed Structured meetings

1.491.49


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Improving IS Development

Productivity

Computer-aided software engineering

(CASE) tools

Facilitate creation of a central repository forsystem descriptions and specifications

Automate repository for easier updating

and for consistency

Diagramming tools for data flow diagrams

and other graphical aids, etc.

1.501.50


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Summary

Information systems analysis and design

Process of developing and maintaining an

information system

Modern approach to systems analysis

Process-Oriented

Focus is on flow, use and transformation of data in an

information system

Data-Oriented

Focus is on the ideal organization of data rather than

where and how data are used

1.511.51


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Summary

Four types of information systems

1.521.52

Transaction Processing (TPS)

Management Information Systems (MIS)

Decision Support (DSS)

Expert Systems (ES)


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Summary

Systems Development Life Cycle

(SDLC)

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Project Identification and Selection Project Initiation and Planning

Analysis

Design

Implementation

Maintenance


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Summary

Alternatives to Systems Development

Life Cycle

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PrototypingRapid Application Development (RAD)

Joint Application Design (JAD)

Computer-aided software engineering(CASE) tools

chapter01 - esssentials of systems analysis and design

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