This document provides an overview of different methodologies in software engineering, including the waterfall model, prototyping model, spiral model, and agile model. It describes the key features, strengths, weaknesses, and appropriate situations for each model. The waterfall model is a sequential approach divided into phases with tight control. Prototyping focuses on user requirements through iterative refinement. The spiral model emphasizes risk assessment through multiple cycles. Agile models prioritize customer satisfaction and rapid delivery through continuous changes.

1. S
Methodologies of
software engineering.
Kaya Ota
San Jose State University Fall 2014
CS146-08

2. Agenda
S Why we need methods of software engineering
S Software development life cycles
S Sequential Approach
S Waterfall model
S Iterative Approach
S Prototype model
S Spiral model
S Agile

3. Why we need a method of
software engineering
S To manage project with a team
S To make a plane of a project

4. Software development life
cycle
S Requirement analysis
S System analysis
S System design
S Coding
S Testing
S Implementation

5. Water Fall
Model
Basic Principles
• Divided into sequential
phases
• Tight control is maintained
over the life of the project
• Focus on planning (time,
budget)
• Implementation of an
entire system at one time.

6. Features of Water Fall Model
Strength
S Generated high-quality
documentations
S Obtains result at the end of
each phases
S Can measure progress of
development
S Well-structured
Weakness
S Difficulty of adaptation to
uncertainty
S Inflexible to respond to change
S Updating documentation is
time-consuming.
S Can not see the working
version of the product until the
end

7. Appropriate situation
Most Appropriate
S Project has clear objectives and
solution
S Project is large and complicated
S Project requirements are stable
(unchanging)
S Required for formal approvals
at designated milestone
Least Appropriate
S Large Project where its
requirements are not well-
understood or changing for any
reasons
S Event-driven systems
S Real-time system

8. Prototyping
• Begin with gathering the
user’s basic requirements.
• Focus on the realization of
the software aspects
visible to the user
• Fully-understand the
requirements by continues
refinement

9. Feature of Prototyping Model
Strength
S Resolving unclear objectives
S Help to identify confusing or
difficult functions
S Have a flexible design
S Provide a quick
implementation(to demonstrate)
Weakness
S Can lead poorly designed
system
S Requirement may change
significantly and frequently
S Incomplete or inadequate
problem analysis may occur

10. Appropriate situation
Most Appropriate
S User is not fully knowledgeable
S Objectives are unclear
S No strict requirement for
approvals at milestone
Least Appropriate
S Transaction-oriented batch
system
S Future scalability of the design
is critical
S Objectives are very clear

11. Spiral Model
S Focus on risk
assessment and
minimize project risk
S Each cycle begins with
an identification of
stakeholders and their
win condition
S Each cycle ends with
review and commitment

12. Feature of Spiral Model
Strength
S Enhances risk avoidance
S Can incorporate waterfall and
prototyping models
Weakness
S No clear termination condition
(so, inherent risk is not meet
time and money)
S Highly customized to each
project => limiting reusability
S No established controls for
moving cycle to cycle

13. Appropriate Situation
Most Appropriate
S Real time or safety-critical
system
S Risk avoidance is high priority
S Required for strong approval
and documentation control
Least Appropriate
S Minimizing resource
consumption is high priority
S Accuracy is not essential
S Risk avoidance is not essential

14. Agile Model

15. Feature of Agile Model
Strength
S Customer satisfaction by rapid
S Continuously delivered of useful
software
S Late changes in requirements
are welcomed
S Get involved business people
and developers
Weakness
S Lack of emphasis on necessary
designing and documentation
S Can easily get taken off if the
customer’s representative is not
clear about their final outcome

16. Feature of Agile Model
Most Appropriate
S When new changes are
required to be implemented.
S Good for a software relative to
dynamic changes in business
or IT world
S Clients can have a various
options
Least Appropriate
S Clients and developer teams
need to be very close.
Communicate well.