Beit 381 se lec 5, 6, 7 & 8 - 69 - 12 feb21,22,28,29 - sw process ...

Ad

Ad

Ad

Ad

Ad

Ad

Ad

Ad

Ad

Ad

Ad

Ad

SE-381
Software Engineering
BEIT-V
Lecture no. 5
Software Engineering Processes
1 of 3

Quality Product
• For a quality software product, both the
quality of product itself and quality of
software process are i...

Boehm 1987 - ‘Industrial Sw Metrics Top 10 List’
1. Finding and fixing a Sw problem after delivery, costs 100 times more t...

$Pareto Analysis or Principle In any series of elements to be controlled, a selected, small fraction, in terms of the numbe...$

Pareto Analysis or Principle implies
• Focus on the problem and try to identify “the vital or
significant few versus the t...

– A detailed analysis of patients revealed that 80% of common diseases,
like fever, cough, cold etc are ‘minor’ diseases a...

Maintenance Aspects
– 1970s Development-then-Maintenance Model
+ Well defined two stages
- Changing Application Environmen...

• For every 1$ spent on development, 2$s are spent on
maintenance
• In 1992, 60%-80% of R & D staff at HP was involved in
...

Failure Curve for Hardware
Software doesn’t wear out but it deteriorates

Idealized and Actual Failure
Curve for Software
Increased Failure rate due to side effects and corrections or bug fixes ma...

Software Process
Is a set of activities and associated results which produce a
Software Product. These activities are carr...

Software Process ..
To introduce visibility in the process different graphical
notations are used to produce different des...

Software Process and Its Components
Software Process
Product
Engineering
Processes
Process
Management
Process
Development
...

Characteristics of Software Process
• Process should be
– Predictable
– Support Testability and Maintainability
– Support ...

SE-381
Software Engineering
BEIT-V
Lecture no. 6
Software Engineering Processes
2 of 3

Software Paradigms
• Classical or Structured Paradigm
• Data Structures and Behavior is loosely connected
• Data Structure...

• Object Oriented Paradigm
• Is a new way of thinking about problems using models organized
around real-world concepts
• F...

Client, User & Developer
• Client
Who initiates and pays for the product and effort
incurred therein, can be a person or a...

Personal / Groups Involved in SD
• Developers
Software Analysts, Architects, Designers,
Programmers or Coders, Testers, Do...

• SQA Division or Section
Solely responsible for assuring quality of the produced
products, directly reporting to CEO. Has...

Re-Cap
• For efficiency and cost effectiveness
– Software should be developed using a phased process
– Testing and Mainten...

Desired Process Properties
• Provide high Quality and Productivity (Q&P)
– Support testability as testing is the most expe...

ETVX Specification
• ETVX approach is to specify at each phase or
step
– Entry criteria: what conditions must be satisfied...

ETVX approach

Testing at Different Phases of
Software Development
• Main Testing Types
Testing could be of Two Types; Non-executable
and...

Requirements Phase
• Input
– Clients (and Users) tell what
they want
– Client’s description of project
– Meetings to under...

Requirements Phase
• Do
– Clarify the constraints, refine
‘What Client wants’ and ‘what
is needed’
– Meetings with develop...

Specification Phase
• Input
– Requirements Doc
• Goal
– Specification Doc should
explicitly describe
• Functionality
• Con...

Specification Phase
• Do
– Consult Client whenever
needed to clarify the
requirements
– Write clearly avoiding
mentioned p...

SE-381
Software Engineering
BEIT-V
Lecture no. 7
Software Engineering Processes
3 of 3

Planning Phase
• Input
– Specification Doc
– Resources Available
– Organizational structure
– SDLC,CASE Tool, Detailed
Sch...

Planning Phase
• Outputs
– Major Components of the
product,
• Milestones / Gantt Charts
• Time & Cost Budget
• Deliverable...

Design Phase
The Most Important Phase
– Specification describes
‘What’ and Design tells
‘How’ the functionality can
be pro...

Design Phase
• Design has 2 or 3 Parts
– Architectural Design
• Break Down of System into
Subsystems, Components and
modul...

Implementation Phase
• Input
– Detailed Design for all the
modules
– Test Cases for the
respective modules
• How to Do
– C...

Integration Phase
• Input
– Specifications of
Modules, Subsystems,
and System; Test Cases,
Structure Chart(s),
Modules’ Co...

Maintenance Phase
• Maintenance starts after
delivery!!
• But
– Maintenance must be kept in
focus while Designing/Coding
…...

Retirement Phase
• When to Retire?
– Further Maintenance is not
Cost-effective
– Write-Only code
– The documentation has
r...

References / Reading Assignment
[Jal97/05] Pankaj Jalote (1997,2005); An Integrated Approach
to Software Engineering; 2nd ...

SE-381
Software Engineering
BEIT-V
Lecture no. 8
Software Process Models
1 of 3

Software Process Models
– Software Development
• Needs to be performed in a series of well-defined steps, so
that the proc...

Some Software Process Models
– Build-n-Fix Model
– Classical Waterfall Model and its variants
– Prototyping Models
• Rapid...

Build and Fix Model

• Pros
– Simplest
– Used by students for
classroom assignments
– Build-use-modify-use-modify
cycle continues until client ...

Waterfall Model
• Pros
– Oldest, Since 1970s
– Found by Winston Royce in
1970
– Most Widely used (in
Aerospace Industry, e...

Waterfall Model
Many organizations still cling to the waterfall model because, even
with its shortfalls, it provides the m...

Classical Waterfall Model

Stage-wise Inputs / Outputs

Waterfall Model with Inter-stage
Feedback

Jal97 – Waterfall Model

Waterfall Model

Waterfall Model .
• Problems
– Real-life systems don’t
work in a simple sequential
mode (so Iterations
implemented)
– Prob...

Waterfall Model ..
Thus limitations of WF model are:
– Requirements of a system are frozen before design begins; could
wor...

Prototyping Model
• Can be used to clarify Requirements, to design Use
Interface, demonstrate feasibility, verify the new
...

Prototyping Model
• Ensures that customer gets what s/he wanted
• Customer is provided a working version of software i.e.
...

Prototyping Model
Prototyping Model could be of two types:
• Rapid or Throwaway prototype Model
• Evolutionary Prototype M...

Prototyping Model
Pressman (1992) –

Prototyping Model
• Problems & Real-life
– Prototyping is a historical
technique of Engineering
Discipline, Chemical Engg,...

Prototyping Model .
• Cons
• The developed Prototype should not be taken as Product
• According to Brooks 1975, it should ...

Rapid Prototyping Model

Jal97 – Prototyping Model

[Bel05] Throwaway Prototype Model

Rapid Prototyping Model
• Pros
– A new model, using
the developed
Prototype as a Front-
end to your SD
process, to gather
...

[Bel05] Evolutionary Prototype Model

Evolutionary Versus Rapid Prototypes
– Rapid Prototypes start from incomplete specifications,
go through a ‘quick’ design ...

Prototyping Model – An Example
Problem Statement
Write a software program that can check the
general knowledge of a user, ...

References
[Bel05] Douglas Bell (2005); Software Engineering for Students,
4th Edition, Pearson Education, New Delhi – Ch ...