information systems design. the systems development life cycle (sdlc) systems planning systems...

INFORMATION SYSTEMS DESIGN

The Systems Development Life Cycle (SDLC)

Systems Planning

Systems Analysis

Systems Design

Systems Implementation

Systems Evolution

Planning

Evolution

Implementation Design

Analysis

System Model with its Six ComponentsSystem Model with its Six Components

SYSTEM

boundary

inputs

outputs

processing

controls

feedback

Examples:• Automobile• Student Registration System• Others...

3

SYSTEMS DESIGNSYSTEMS DESIGN

people

procedures

data

software

hardware

An AUTOMATED INFORMATION An AUTOMATED INFORMATION SYSTEM ISSYSTEM IS

a type of fabricated system used by one or more persons to help people accomplish some task

or assignment that they have

utilizes hardware and software

DATA - input, output or already stored DATA - input, output or already stored

electronicallyelectronically

FUNCTIONS - transformations or actions takenFUNCTIONS - transformations or actions taken

BEHAVIOR - the observable effects from BEHAVIOR - the observable effects from

interactioninteraction

SYSTEMS DESIGNSYSTEMS DESIGN

DATA FUNCTIONS

BEHAVIOR

An AUTOMATED INFORMATIONAn AUTOMATED INFORMATION

SYSTEM has three basicSYSTEM has three basic

relationships to considerrelationships to consider

General Model of Information Systems Development (“Partnership”)

Requirements Specification(3)

Stakeholder

InformationTechnology

Staff

Analysis Design andImplementation

Requirements(1) Continued

Involvement(5)

InformationSystem (6)

ProblemDefinitionSkills (2)

ProblemSolutionSkills (4)

Systems Analysis and Design Activities and Deliverables

ANALYSIS

Activities:

• Systems Planning• Feasibility Study (optional)• Requirements Determination• User Acceptance• Prototyping (optional)

Deliverables:

• Requirements Specification• Prototype (optional)

DESIGN

Activities:

Deliverable:

• Physical Design• Prototyping (optional)• Software Construction/Purchase• User Documentation - “Deliverable”• Testing• Training• User Acceptance• Conversion• Implementing the system

• Information System

• Project Management • Project Documentation - “Scaffolding”

Two on-going activities

In addition: User acceptance, documentation, project management

Planning Feasibility Study (optional) Requirements Determination Conceptual Design Physical Design Construction and/or Purchase

(prototype) Training Conversion - old to new Implementation Evolution - maintenance &

enhancements

SYSTEMS DEVELOPMENT LIFE CYCLE (SDLC)SYSTEMS DEVELOPMENT LIFE CYCLE (SDLC)A

naly

sis

Desig

n

8

Economic, Operational & Technical Feasibility

Security Issues

Make (in-house versus outsource) versus Buy

Documentation

Software testing (next slide)

SYSTEMS DESIGN SYSTEMS DESIGN ACTIVITIESACTIVITIES

1 of 3

INFORMATION SYSTEMS TESTING INFORMATION SYSTEMS TESTING LAYERSLAYERS

Module

FunctionSub-system

System and Integration

User Acceptance

CreepingCommitment

Alpha &Beta tests

2 of 3

•

•

User-Interface Design (GUI design)

Prototyping

Training

Conversion - cutover and parallel

Implementation - install, activate, institutionalize

SYSTEMS DESIGN SYSTEMS DESIGN ACTIVITIESACTIVITIES

3 of 3

Verification and Validation* Verification: The process of evaluating a system or

component to determine whether the products of a given phase satisfy the conditions imposed at the start of that phase. (Mainly a paper-based activity that requires you to confirm that each stage of the development conforms to the requirements defined in the previous stage.)

Validation: The process of evaluating a system or component during or at the end of the development process to determine whether it satisfies specified requirements. (Mainly a confirmation that the implemented system/component actually works to specification.)

* IEEE Standard Glossary of Software Engineering Terminology, 1994

OBJECT-ORIENTED SYSTEMS OBJECT-ORIENTED SYSTEMS DESIGNDESIGN

Problem Domain (PD)

Data Management (DM) System Interaction (SI)

Information System Model

(created during analysis;refined during design)

Human Interaction (HI)

• Good strategy (technique) for developing Client-Server (n-Tier) Systems

Log Information Conduct Business

Analyze results Interact with other systems

Types of Information System Features

(“needed information”) •Business Problem Master/Reference Data

• Business Problem Transaction Data

• Business Problem Results• Business Problem Integration

Student

registerForCoursedropCourserequestTranscriptpayStudentFeesetc...

studentIDNumberstudentNameetc...

ProblemDomainHuman Interaction

RegForCourseWin

Student

services

DropCourseWin

Student

services

RequestTranscriptWinStudent

services

PayStudentFeesWin

Student

services

LogonWindow

attributes

services

The HI to PD Relationship

ProblemDomain

DataManagement SystemInteraction

Information System

HumanInteraction

• Business Problem

• Devices• Other Systems

• Screens• Reports

• Databases

Security/Logon Window(s)

Setup Windows - persistent

objects

Business Function Windows -

supports the human interface for

the Problem Domain functionality



Human InteractionCheck-InWindow

CustomerWindowEmployeeWindowInventoryWindowLogonWindow PurchaseOrderWindowSale-RentWindowVendorWindowCustomerStatusReportDailySalesRentReportInventoryStatusReportOverdueRentalItemReportOpenPurchaseOrderReportSaleRentReceiptReport


Video Store Example


Compare this list with theVideo Store’s PD Component

Human InteractionCheck-InWindow

CustomerWindowEmployeeWindowInventoryWindowLogonWindow PurchaseOrderWindowSale-RentWindowVendorWindowCustomerStatusReportDailySalesRentReportInventoryStatusReportOverdueRentalItemReportOpenPurchaseOrderReportSaleRentReceiptReport

Check-InWindow

attributes

services

CustomerWindow

attributes

services

EmployeeWindowattributes

services

InventoryWindow

attributes

services

LogonWindow

attributes

services

PurchaseOrderWindow

attributes

services

.....plus 8 more


Who “I” Know - connections &

constraints

What “I” Know - attributes

What “I” Do - services



Stores the problem domain

classes with objects that are

persistent

Encapsulates search & storage

mechanisms for all persistent

classes with objects

Data Management (DM)


Data Management

Problem DomainConcessionItemEmployeeGameInventoryMemberPOLineItemPurchaseOrderRentalItemRentalTransactionSaleItemSaleRentalLineItemSalesTransactionStoreLocationTransactionVCRVendorVideo

ConcessionItemDMEmployeeDMGameDMMemberDMPOLineItemDMPurchaseOrderDMRentalTransactionDMSaleRentalLineItemDMSalesTransactionDMStoreLocationDMVCRDMVendorDMVideoDM

Problem Domainclass with objectsthat need persistencewill most oftencorrespond directly with the DM class with objects.

Reason: “Plug-and-Play” concept or the “Separation of Concerns” concept


INFORMATION SYSTEMS INFORMATION SYSTEMS DESIGNDESIGN

ANALYSIS DESIGN PROGRAMMING DATABASE

Structured

Structured

Object

Object

Object

Object

Structured

Object

Structured

Object

Object

Object

Object

Object

Conventional, 3rd/4th GL

Conventional, 3rd/4th GL

Mix of Conventional/Object

Object

RDBMSOODBMSRDBMSOODBMSRDBMS

RDBMS

RDBMSOODBMSOODBMS

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