System development life cycle (SDLC) CS208

Июль 23, 2022

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System development life cycle (SDLC) CS208

Содержание

2. Six Phases of the System Development Life Cycle Preliminary Investigation Assesses feasibility and practicality of system
3. Six Phases of the System Development Life Cycle System Development New hardware and software is acquired,
4. SDLC Phases Preliminary Investigation System Operation & Maintenance System Analysis System Implementation n System Design System
5. Phase 1: Preliminary Investigation Determine if a new system is needed Three primary tasks: Define the
6. In depth study of the existing system to determine what the new system should do. Expand
7. Phase 2: System Analysis Tools Used Checklists - list of questions Top-down analysis - start with
8. Phase 2: System Analysis Documentation Produced Complete description of current system and its problems Requirements for
9. Phase 3: System Design Uses specifications from the systems analysis to design alternative systems Evaluate alternatives
10. Phase 3: System Design Tools Used Computer-Aided Software Engineering (CASE) tools are software-based products designed to
11. Phase 3: System Design Documentation Produced System Design Report Describe Alternatives including: Inputs/Outputs Processing Storage and
12. Phase 4: System Development Build the system to the design specifications Develop the software Purchase off-the-shelf
13. Phase 5: System Implementation Convert from old system to new system Train users Compile final documentation
14. Phase 5: System Implementation Types of Conversion Direct/plunge/crash approach – entire new system completely replaces entire
15. Phase 5: System Implementation User Training Ease into system, make them comfortable, and gain their support
16. Phase 6: Operations & Maintenance Types of changes: Physical repair of the system Correction of new
17. Phase 6: Operations & Maintenance Evaluation Methods Systems audit - performance compared to original specifications Periodic
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Слайд 2

Six Phases of the System Development Life Cycle
Preliminary Investigation
Assesses feasibility

and practicality of system
System Analysis
Study old system and identify new requirements
Defines system from user's view
System Design
Design new/alternative system
Defines system from technical view

Слайд 3

Six Phases of the System Development Life Cycle
System Development
New hardware and

software is acquired, developed, and tested
System Implementation
System installation and training
System Operation & Maintenance
Daily operation
Periodic evaluation and updating

Слайд 4

SDLC Phases

Preliminary

Investigation

System Operation
& Maintenance

System

Analysis

System

Implementation

System

Design

System

evelopment

Слайд 5

Phase 1: Preliminary Investigation
Determine if a new system is needed
Three primary

tasks:
Define the problem
By observation and interview, determine what information is needed by whom, when, where and why
Suggest alternative solutions
Prepare a short report

Слайд 6

In depth study of the existing system to determine what the

new system should do.
Expand on data gathered in Phase 1
In addition to observation and interviews, examine:
Formal lines of authority (org chart)
Standard operating procedures
How information flows
Reasons for any inefficiencies

Phase 2: System Analysis

Слайд 7

Phase 2: System Analysis Tools Used
Checklists - list of questions
Top-down analysis

- start with top level components, break down into smaller parts through each successive level
Grid charts - to show relationship between inputs and outputs
System flowcharts - charts flow of input data, processing, and output which show system elements and interactions

Слайд 8

Phase 2: System Analysis Documentation Produced
Complete description of current system and

its problems
Requirements for for new system including:
Subject
Scope
Objectives
Benefits
Possible development schedule

Слайд 9

Phase 3: System Design
Uses specifications from the systems analysis to design

alternative systems
Evaluate alternatives based upon:
Economic feasibility - Do benefits justify costs?
Technical feasibility - Is reliable technology and training available?
Operational feasibility - Will the managers and users support it?

Слайд 10

Phase 3: System Design Tools Used
Computer-Aided Software Engineering (CASE) tools are software-based

products designed to help automate the production of information systems.
Examples:
Diagramming Tools
Data Repositories
Prototyping Tools
Test Data Generators
Documentation Tools
Project Management Tools

Слайд 11

Phase 3: System Design Documentation Produced
System Design Report
Describe Alternatives including:
Inputs/Outputs
Processing
Storage and Backup
Recommend

Top Alternative based upon:
System Fit into the Organization
Flexibility for the future
Costs vs. benefits

Слайд 12

Phase 4: System Development
Build the system to the design specifications
Develop

the software
Purchase off-the-shelf software OR
Write custom software
Acquire the hardware
Test the new system
Module (unit) test - tests each part of system
Integration testing - tests system as one unit
Create manuals for users and operators

Слайд 13

Phase 5: System Implementation
Convert from old system to new system
Train users
Compile

final documentation
Evaluate the new system

Слайд 14

Phase 5: System Implementation Types of Conversion
Direct/plunge/crash approach – entire new system

completely replaces entire old system, in one step
Parallel approach - both systems are operated side by side until the new system proves itself
Pilot approach - launched new system for only one group within the business -- once new system is operating smoothly, implementation goes company-wide
Phased/incremental approach - individual parts of new system are gradually phased-in over time, using either crash or parallel for each piece.

Слайд 15

Phase 5: System Implementation
User Training
Ease into system, make them comfortable, and

gain their support
Most commonly overlooked
Can be commenced before equipment delivery
Outside trainers sometimes used

Слайд 16

Phase 6: Operations & Maintenance
Types of changes:
Physical repair of the system
Correction

of new bugs found (corrective)
System adjustments to environmental changes
Adjustments for users’ changing needs (adaptive)
Changes to user better techniques when they become available (perfective)

Слайд 17

Phase 6: Operations & Maintenance
Evaluation Methods
Systems audit - performance compared to

original specifications
Periodic evaluation - “checkups” from time to time, modifications if necessary

System development life cycle (SDLC) CS208

Содержание

Six Phases of the System Development Life CyclePreliminary Investigation Assesses feasibility

Six Phases of the System Development Life CycleSystem DevelopmentNew hardware and

SDLC Phases Preliminary Investigation System Operation & Maintenance System

Phase 1: Preliminary InvestigationDetermine if a new system is neededThree primary

In depth study of the existing system to determine what the

Phase 2: System Analysis Tools UsedChecklists - list of questionsTop-down analysis

Phase 2: System Analysis Documentation ProducedComplete description of current system and

Phase 3: System DesignUses specifications from the systems analysis to design

Phase 3: System Design Tools UsedComputer-Aided Software Engineering (CASE) tools are software-based

Phase 3: System Design Documentation ProducedSystem Design ReportDescribe Alternatives including:Inputs/OutputsProcessingStorage and BackupRecommend

Phase 4: System DevelopmentBuild the system to the design specifications Develop

Phase 5: System ImplementationConvert from old system to new systemTrain usersCompile

Phase 5: System Implementation Types of ConversionDirect/plunge/crash approach – entire new system

Phase 5: System ImplementationUser TrainingEase into system, make them comfortable, and

Phase 6: Operations & MaintenanceTypes of changes:Physical repair of the systemCorrection

Phase 6: Operations & MaintenanceEvaluation MethodsSystems audit - performance compared to

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Six Phases of the System Development Life Cycle
Preliminary Investigation
Assesses feasibility

Six Phases of the System Development Life Cycle
System Development
New hardware and

SDLC Phases

Preliminary

Investigation

System Operation
& Maintenance

System

Phase 1: Preliminary Investigation
Determine if a new system is needed
Three primary

Phase 2: System Analysis Tools Used
Checklists - list of questions
Top-down analysis

Phase 2: System Analysis Documentation Produced
Complete description of current system and

Phase 3: System Design
Uses specifications from the systems analysis to design

Phase 3: System Design Tools Used
Computer-Aided Software Engineering (CASE) tools are software-based

Phase 3: System Design Documentation Produced
System Design Report
Describe Alternatives including:
Inputs/Outputs
Processing
Storage and Backup
Recommend

Phase 4: System Development
Build the system to the design specifications
Develop

Phase 5: System Implementation
Convert from old system to new system
Train users
Compile

Phase 5: System Implementation Types of Conversion
Direct/plunge/crash approach – entire new system

Phase 5: System Implementation
User Training
Ease into system, make them comfortable, and

Phase 6: Operations & Maintenance
Types of changes:
Physical repair of the system
Correction

Phase 6: Operations & Maintenance
Evaluation Methods
Systems audit - performance compared to