1. Systems Analysis and Design II
Describing Methodologies
PART I
SDLC and Rapid Application Development*

2. Learning Objectives Describe the Traditional Methodologies
Systems Development Life Cycle (SDLC).
Waterfall Model (SDLC Waterfall)
Enhanced Waterfall Model
Explain Rapid Application Methodologies
Prototyping,
Joint Application Development (JAD)
Rapid Application Development (RAD),
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3. Approaches to Systems Analysis and Design
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4. A: Traditional Methodologies.
1. Systems Development Life Cycle (SDLC)
Traditional methodology used to develop, maintain, and replace information systems.
Phases in SDLC:
Planning
Analysis
Design
Implementation
Maintenance
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5. Standard and Evolutionary Views of SDLC
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6. Systems Development Life Cycle (SDLC) (Cont.)
Planning – an organization’s total information system needs are identified, analyzed, prioritized, and arranged.
Analysis – system requirements are studied and structured.
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7. Systems Development Life Cycle (SDLC) (Cont.)
Design – a description of the recommended solution is converted into logical and then physical system specifications.
Logical design – all functional features of the system chosen for development in analysis are described independently of any computer platform.
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8. Systems Development Life Cycle (SDLC) (Cont.)
Physical design – the logical specifications of the system from logical design are transformed into the technology-specific details from which all programming and system construction can be accomplished.
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9. Systems Development Life Cycle (SDLC) (Cont.)
Implementation – the information system is coded, tested, installed and supported in the organization.
Maintenance – an information system is systematically repaired and improved.
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11. 2. Traditional Waterfall SDLC
The same as previously discussed SDLC
Only unique feature is ----
One phase begins when another completes, little backtracking and looping
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12. Problems with Waterfall Approach
System requirements “locked in” after being determined (can't change).
Limited user involvement (only in requirements phase).
Too much focus on milestone deadlines of SDLC phases to the detriment of sound development practices.
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13. 3. Enhanced Waterfall SDLC
Planning
Analysis
Logical
Design
Physical
Implementation
Maintenance
Enhanced Waterfall SDCL allows flexibility in development process specifically to minimize errors and producing a required system.
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14. B: Rapid Application Methodologies.
Effort to improve systems analysis and design process, several different approaches have been developed.
Rapid Application methodologies share two key advantages
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15. B: Rapid Application Methodologies. (Cont..)
1. Prototyping
An iterative process of system development in which requirements are converted to a working system that is continually revised through close collaboration between analyst and users
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16. Prototyping (Cont.)
Prototype addresses some of the problem of traditional systems analysis; in particular
The complaints that users only see their information system at implementation
Too late to make changes
Analyst to experiment on the users instead of the system.
The first version of the system is also the final version, etc
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17. Prototyping (Cont.)
In information systems there are different kinds of prototype with different objectives.
The most common use of prototype is to examine area where the user and analyst are unsure of the requirement and feel they need tease out and explore the real needs by showing and amending a physical approximation of a system.
There are two types of prototypes
A throwaway (or expendable) prototype
An evolutionary prototype.
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18. Prototyping (Cont.)
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19. Prototyping (Cont.) Identify Problem Develop Prototype
stage of minimally indentifying and describing a problem.
The application area is not well defined and the organization in not familiar with the technology.
Develop Prototype
Construct a prototype for evaluation by users;
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20. Prototyping (Cont.) Implement and Use Prototype
A process of indentifying true organizational and user need for the problem/opportunity at hand;
Revise and Enhance Prototype
A set of evaluation and prototype modification stage;
Convert to Operational System
Using the prototype as an operational system.
Tools for Prototyping are CASE tools
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21. Prototyping (Cont.) Some advantages of Prototyping
Reduces development time.
Reduces development costs.
Requires user involvement.
Developers receive quantifiable user feedback.
Facilitates system implementation since users know what to expect.
Results in higher user satisfaction.
Exposes developers to potential future system enhancements.
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22. Prototyping (Cont.) Some Disadvantages of Prototyping
Can lead to insufficient analysis.
Users expect the performance of the ultimate system to be the same as the prototype.
Developers can become too attached to their prototypes
Can cause systems to be left unfinished and/or implemented before they are ready.
Sometimes leads to incomplete documentation.
If sophisticated software prototypes (4th GL or CASE Tools) are employed, the time saving benefit of prototyping can be lost.
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23. Summary In this Lecture you have learned
The differences between Traditional and Rapid Systems Methodologies
Types and steps that can be adapted for Traditional
SDLC
Waterfall SDLC
Rapid Application Methodologies
Prototyping (1)
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