2. System Development Model
System development model specifies how the
activities are organized in the total system
development effort.The various model for system
development are:-
1. Waterfall Model
2. Prototyping
3. Iterative enhancement Model
4. Spiral Model
3. Waterfall Model
The model states that the phases are organized
in a linear order. In other words, output of one
phase becomes the input for the next phases.
The different phases of the waterfall model
are:
1. Proposal Definition
2. Feasibility Study
3. Requirement Analysis
4. System Design
5. Coding & Testing
6. Implementation
7. System Maintenance
5. Limitations of the Waterfall
Model
1. The waterfall model assumes that the
requirements of a system can be frozen before
the design begins. But for new systems,
determining the requirements is difficult, as the
user does not even know the requirements.
Hence, having unchanging requirements is
unrealistic for such projects.
2. This model stresses that the requirements
should be completely specified before the
beginning of the next phase. But it is not possible
in all the systems.
6. Prototyping Model
A prototype approach, a prototype of the system is
developed, instead of the complete system. A
prototype is a comprehensive system and does not
include all the requirement of the user. Prototype is
used in those systems, in which identification of
requirement is difficult and requirement the
requirement may change during the development
process.
8. This model has four steps
Identify the user’s basic information Requirements
Develop the initial prototype system
Use of the prototype system to refine the user’s
requirement
Revise and enhance the prototype system
9. Limitations
This approach requires at least two iterations. It may
become an unending process of refinement, which
may take too much time, effort and money.
Due to frequent changes, management of the
development process also becomes difficult.
10. Iterative Enhancement Model
In an iterative enhancement model, the system is
developed in increments and each increment adds
some functional capabilities to the system, until the
full system is developed. Additions and Modifications
is done at each step.
12. Limitations
The model does not give the complete information
system and thus many of the details may not be
incorporated in the development system.
As the model is based on modify-it-again approach it
may be time consuming and is not cost-effective.
13. Spiral Model
This model, as the indicates is cyclic in nature. Each
cycle of the spiral consists of four stages
represented by one quadrant each. The angular
dimension represents the progress in the
development process, where as the radius of the
spiral represent the cost involved.