ITM 362 Lecture - 2
Transcript of ITM 362 Lecture - 2
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Systems Analysis and Design Lecture Slides
by: Maxwell Dorgbefu Jnr. 1
ITM 362; SYSTEMS ANALYSISAND DESIGN
LECTURE TWO
1. THE SYSTEMDEVELOPMENT LIFE CYCLE
(SDLC).
Systems Analysis and Design Lecture Slides
by: Maxwell Dorgbefu Jnr.
Key Ideas
An opportunity to create business value fromusing information technology initiates a project.
Feasibility analysis helps determine whether ornot to proceed with the IS project.
Projects are selected based on business needsand project risks.
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Key Ideas
The project sponsor is a key person whoidentifies business value to be gained fromusing information technology.
The approval committee reviews systemrequests from groups throughout theorganization and selects projects for the benefitof the business.
Systems Analysis and Design Lecture Slides
by: Maxwell Dorgbefu Jnr.
System Development Life Cycle(SDLC)
The Systems Development Life Cycle (SDLC) is ageneral term used to describe the method andprocess of developing a new information system.
Without the structure and organization providedby SDLC approach, projects are at risk for misseddeadline, low quality etc.
SDLC provides Structure
Methods Controls
Checklist
Needed for successful information system development.
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Why SDLC ?
We need SDLC in Information Systems
development to:
Facilitate project review
Improve communication
Provide a more efficient/effective system
Guide the system development
Improve management and control
Ensure systems are within budget and meetuser/clients taste.
Systems Analysis and Design Lecture Slides
by: Maxwell Dorgbefu Jnr.
SDLC Phases - 1Sets of related activities are organized into phases:
1. Preliminary investigation
2. System Analysis
3. System Design
4. System Development
5. System Implementation and6. System Support and Maintenance
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SDLC Phases - 1
1.
Preliminary
Investigation
4. System
Development
Starting Point
Systems Analysis and Design
Lecture Slides by: Maxwell
Dorgbefu Jnr.
The 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
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Analysis Phase
Primary objective: to understand and document the
information needs and processing requirements of
the new system.
Gather information (e.g. interview, read, observe etc.)
Define system requirements (reports, diagrams etc.)
Build prototypes for discovery of requirements
Prioritize requirements
Generate and evaluate alternative solutions Review recommendations with management
Systems Analysis and Design Lecture Slides
by: Maxwell Dorgbefu Jnr.
Analysis Phase Understand the existing system
Gather data
Analyze data
Establish system requirements
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Analysis- Data Gathering
Written documents
InterviewsStructuredUnstructured
Questionnaires
ObservationVisits by appointmentParticipant observation
Sampling
Systems Analysis and Design Lecture Slides
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Analysis-Analyze Data How the current system works
Determine system requirements
Basis for documentation
Tools
Data flow diagram (DFD)
Decision tables
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Analysis System Requirements
Detailed list of things the system must be able
to do
Design is based upon system requirements
Agreement upon requirements is needed
before proceeding
Systems Analysis and Design Lecture Slides
by: Maxwell Dorgbefu Jnr.
Analysis Report to Management
Summarize problems
Describe requirements
Cost analysis
Recommendations for next step
Obtain authorization to proceed
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Design Phase
Objective: to design the solution (not to
implement it though)
The two sub phases of the design phase are:
Preliminary design
Detail design
Systems Analysis and Design Lecture Slides
by: Maxwell Dorgbefu Jnr.
Design Phase Preliminary Design
Major system aspects
Centralized or distributed
Online or batch
PC-based?
How will input be captured?
Necessary reports
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Design Phase Preliminary Design
Make or buy decision
Packaged softwareMeet at least 75% of requirements?Change business procedures for part or all of
remainder?Customize for part of all of remainder?
Custom softwareProgrammers write code
OutsourcingSystem is developed by external organization
Systems Analysis and Design Lecture Slides
by: Maxwell Dorgbefu Jnr.
Design Phase Preliminary Design
Build a prototype
Limited working system of subset
Does not need true functionality
Output looks like anticipated system output
Working model that can be modified and fine-tuned
Uses high-level software tools CASE Best for small-scale systems
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Design Phase Preliminary Design
Presentation
All alternatives
Selected plan
Prototype of the system
Obtain authorization to proceed
Systems Analysis and Design Lecture Slides
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Design Phase Detail Design
Parts of detail design phase
Output requirements
Input requirements
Files and databases
Systems processing
Systems controls and backup
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Output requirements
Medium
Type of reports
Contents
Input requirements
Medium
Content
Input forms
Validation
Volume
Design Phase Detail Design
Files and Databases
Organization
Access
Format of records
Coordinate with database administrator
regarding external databases and updating
Systems Analysis and Design Lecture Slides
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Design Phase Detail Design
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Design Phase Detail Design
Systems Controls and Backup
Ensure that input is processed correctly
Prevent fraud and tampering
System journals
Backup of system files
Systems Analysis and Design Lecture Slides
by: Maxwell Dorgbefu Jnr.
Design Phase Detail Design
Report to Management
Detailed design specifications report
Presentation
Obtain authorization to proceed
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Development Phase
Doing the work to bring the new system into
being
This phase involves
Scheduling
Coding/Programming and
Testing
Systems Analysis and Design Lecture Slides
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Development Phase Programming
Refine the design
Converting detailed logic flowcharts and
pseudocode into programs
Testing
Unit testing
System testing
Volume testing
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Implementation Phase
Information system is built, tested and installed
(actual programming of the information system)
Activities
Construct software components
Verify and test
Develop prototypes for tuning
Convert data
Train and document Install the system
Systems Analysis and Design Lecture Slides
by: Maxwell Dorgbefu Jnr.
Implementation - 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
Pilotapproach - 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 ofnew system are gradually phased-in over time, using
either crash or parallel for each piece.
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Support and Maintenance Phase
Objective is to keep the information system running afterits installation.
Maintain system
Small patches, repairs, and updates
Enhance system
Small upgrades or enhancements to expand systemcapabilities
Larger enhancements may require separatedevelopment project
Support users
Help desk and/or support team
Systems Analysis and Design Lecture Slides
by: Maxwell Dorgbefu Jnr.
End of Lecture !!!
See you next week.
Systems Analysis and Design Lecture Slides
by: Maxwell Dorgbefu Jnr.
Questions & Comments ???.....