Discovering Computers 2012Chapter 12Exploring Information System Development

(1)

Your Interactive Guide to the Digital World

Discovering

Computers 2012 Chapter 12

Exploring Information System Development

(2)

Objectives Overview

Define system development and list the system development phases Define system development

and list the system development phases

Identify the guidelines for system development Identify the guidelines for

system development

Discuss the importance of project management, feasibility assessment, documentation, and data and information gathering

techniques

Discuss the importance of project management, feasibility assessment, documentation, and data and information gathering

techniques

Explain the activities performed in the planning

phase

Explain the activities performed in the planning

phase

Discuss the purpose of the activities performed in the

analysis phase

Discuss the purpose of the activities performed in the

analysis phase

Describe the various tools used in process modeling Describe the various tools

used in process modeling

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Objectives Overview

Describe the various tools used in object

modeling

Describe the various tools used in object

modeling

Explain the activities performed in the

design phase

Explain the activities performed in the

design phase

Recognize the develop programs activity is

part of system development

Recognize the develop programs activity is

part of system development

Discuss the activities performed in the implementation phase

Discuss the purpose of the activities performed

in the operation, support, and security

phase

Discuss the purpose of the activities performed

in the operation, support, and security

phase

Discovering Computers 2012: Chapter 12 3

See Page 619

for Detailed Objectives

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What is System Development?

System development is a set of activities used to build an information system

A system is a set of components that interact to achieve a

common goal

An information system (IS) is a

collection of

hardware, software, data, people, and procedures that work

together to produce quality information

System development activities are grouped

into phases,

collectively called the system development

life cycle (SDLC)

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Discovering Computers 2012: Chapter 12 5 Pages 620 – 621

Figure 12-1

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What is System Development?

• System development should follow three general guidelines:

Group activities or tasks into phases Group activities or tasks into phases

Involve users

Define standards

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What is System Development?

• System development should involve representatives from each department in which the proposed system will be used

Page 622 Figure 12-2

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What is System Development?

• Project management is the process of planning,

scheduling, and then controlling the activities during system development

• To plan and schedule a project efficiently, the project leader identifies:

Project scope

Project scope Required activities Required

activities Time estimates for each activity Time estimates for each activity

Cost estimates for each activity Cost estimates

for each activity Order of activities

Order of activities

Activities that can take place at

the same time Activities that can take place at

the same time

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What is System Development?

Page 623 Figure 12-3a

A popular tool used to plan and schedule

the time relationships among project

activities is a Gantt chart

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What is System Development?

A PERT chart also can be

used for planning and scheduling time

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What is System Development?

• Feasibility is a measure of how suitable the development of a system will be to the

organization

Pages 624 - 625

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What is System Development?

• Documentation is the collection and summarization of data and information

– A project notebook contains all documentation for a single project

• Users and IT professionals refer to existing

documentation when working with and modifying current systems

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What is System Development?

• During system development, members of the project team gather data and information using several

techniques

Pages 625 – 626 Figure 12-4

Review documentation

Review

documentation ObserveObserve SurveySurvey

Interview

Interview JAD SessionsJAD Sessions ResearchResearch

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Who Initiates a System Development Project?

A user may request a new or modified system A user may request a new or modified system

Organizations may want to improve hardware, software, or other technology

Situations beyond an organization’s control might require a change Situations beyond an organization’s control might require a change

Management might mandate a change Management might mandate a change

A user may request a new or modified information system using a request for system services or a project request

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Discovering Computers 2012: Chapter 12 15 Page 627

Figure 12-5

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Planning Phase

• The planning phase for a project begins when the steering committee receives a project request

• Four major activities are performed:

Review and approve the project requests

Prioritize the project requests

Prioritize the

project requests Allocate resources

Allocate resources

Form a project development

team

Form a project development

team

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Analysis Phase

• The analysis phase consists of two major activities:

Pages 629 - 631

Conduct a preliminary investigation

Conduct a preliminary investigation

• Determines and defines the exact

nature of the problem or improvement

• Interview the user who submitted the request

• Determines and defines the exact

nature of the problem or improvement

• Interview the user who submitted the request

Perform detailed analysis

• Study how the current system works

• Determine the users’

wants, needs, and requirements

• Recommend a solution

• Study how the current system works

• Determine the users’

wants, needs, and requirements

• Recommend a solution

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Analysis Phase

• Process modeling (structured analysis and design) is an analysis and design technique that describes processes that transform inputs into outputs

Page 631

Entity-

relationship diagrams

Entity-

relationship diagrams

Data flow diagrams Data flow

diagrams

Project dictionary

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Analysis Phase

• An entity-relationship diagram (ERD) is a tool that graphically shows the connections among entities in a system

• Entities are objects in the system that have data

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Analysis Phase

• A data flow diagram (DFD) is a tool that graphically shows the flow of data in a system

– Data flows – Processes – Data stores – Sources

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Analysis Phase

• The project dictionary contains all the

documentation and deliverables of a project

• Structured English is a style of writing that describes the steps in a process

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Analysis Phase

A decision table is a table that lists a variety of conditions

and the actions that

correspond to each condition

A decision tree also shows conditions and actions, but it shows them graphically

Page 633

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Decision table

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Decision tree

Page 633

Figures 12-10 – 12-11

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Analysis Phase

• The data dictionary stores the data item’s name, description, and other details about each data item

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Analysis Phase

• Object modeling combines the data with the processes that act on that data into a single unit, called an object

• UML (Unified Modeling Language) has been adopted as a standard notation for object modeling and development

– UML includes 13 different diagrams – Two diagrams include:

Page 634

Use case

diagram Class diagram

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Analysis Phase

• A use case diagram graphically shows how actors (users) interact with the information system

• Diagrams are

considered easy to understand

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Analysis Phase

• A class diagram graphically shows

classes and subclasses in a system

• Each class can have one or more subclasses

• Subclasses use

inheritance to inherit methods and attributes of higher levels

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Analysis Phase

• The system proposal assesses the feasibility of each alternative solution

• The steering committee discusses the system

proposal and decides which alternative to pursue

Packaged software Packaged

software Custom software Custom

software OutsourcingOutsourcing

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Design Phase

• The design phase consists of two major activities

Page 638

Acquire hardware and software Acquire hardware

and software

Develop all of the details of the new

or modified information system

Develop all of the details of the new

or modified information system

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Design Phase

• To acquire the necessary hardware and software:

• Use research techniques such as e-zines

Identify technical specifications

• RFQ, RFP, or RFI is sent to potential vendors or VARs

Solicit vendor

proposals • Various techniques are used to

determine the best proposal

Test and evaluate vendor proposals

• Systems analyst makes

recommendation to steering committee

Make a decision

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Design Phase

• The next step is to develop detailed design specifications

– Sometimes called a physical design

Page 640

Database design

Input and output

design

Program design

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Design Phase

• Systems analysts typically develop two types of designs for each input and output

Mockup Layout chart

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Design Phase

• A prototype (proof of concept) is a working model of the proposed system

– Prototypes have inadequate or missing documentation – Users tend to embrace the prototype as a final system – Should not eliminate or replace activities

Pages 641 - 642

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Design Phase

• Computer-aided software engineering (CASE) tools are designed to support one or more

activities of system development

• CASE tools sometimes contain the following tools:

Project repository

Project

repository GraphicsGraphics PrototypingPrototyping

Quality assurance

Quality

assurance Code

generator Code

generator HousekeepingHousekeeping

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Discovering Computers 2012: Chapter 12 37 Page 642

Figure 12-20

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Design Phase

• Many people should review the detailed design specifications

• An inspection is a formal review of any system development deliverable

– A team examines the deliverables to identify errors

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Implementation Phase

• The purpose of the implementation phase is to construct the new or modified system and then deliver it

Page 643

Develop programs Develop programs

Install and test the new

system Install and test the new

system Train usersTrain users Convert to the new

system Convert to

the new system

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Implementation Phase

• The program development life cycle follows these steps: ₁ ₁ _ts ts _emen emen _uir uir _{e req} e req _{e th} e th _alyz alyz _•An _•An

2 2 on on uti uti e sol e sol n th n th esig esig •D •D

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5 5 n n tio tio lu lu so so the the est est •T •T

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Implementation Phase

• Various tests should be performed on the new system

Page 644

Unit test Unit test

• Verifies that each

individual program or object works by itself

• Verifies that each

individual program or object works by itself

Systems test Systems test

• Verifies that all programs in an

application work

together properly

• Verifies that all programs in an

application work

together properly

Integration test

• Verifies that an

application works with other

applications

• Verifies that an

application works with other

applications

Acceptance test

• Checks the new system to ensure that it works with actual data

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Implementation Phase

• Training involves showing users exactly how they will use the new hardware and software in the

system

– One-on-one sessions

– Classroom-style lectures – Web-based training

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Implementation Phase

• One or more of four conversion strategies can be used to change from the old system to the new system

Pages 644 – 645 Figure 12-22

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Operation, Support, and Security Phase

• The purpose of the operation, support, and

security phase is to provide ongoing assistance for an information system and its users after the

system is implemented

Perform maintenance

activities Perform maintenance

activities

Monitor system performance

Assess system security

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Operation, Support, and Security Phase

• A computer security plan should do the following:

Page 646

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(46)

Video: Create a Hidden Operating System

CLICK TO START

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Summary

System

development phases

System

development phases

Guidelines for system

development Guidelines for

system

development

Activities that occur during system

development

Activities that occur during system

development

Activities

performed during each system

development phase Activities

performed during each system

development phase

Page 647

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Your Interactive Guide to the Digital World

Discovering

Computers 2012 Chapter 12

Exploring Information System Development