software engineering notes for msc stude

These courseware materials are to be used in conjunction with Software Engineering: A Practitioner’s Approach, 6/e and
are provided with permission by R.S. Pressman & Associates, Inc., copyright © 1996, 2001, 2005 1
Software Engineering: A Practitioner’s Approach, 6/e
Software Engineering: A Practitioner’s Approach, 6/e
Chapter 4
Chapter 4
Agile Development
Agile Development
copyright © 1996, 2001, 2005
R.S. Pressman & Associates, Inc.
For University Use Only
May be reproduced ONLY for student use at the university level
when used in conjunction with Software Engineering: A Practitioner's Approach.
Any other reproduction or use is expressly prohibited.

The Manifesto for
The Manifesto for
Agile Software Development
Agile Software Development
“
“We are uncovering better ways of developing
We are uncovering better ways of developing
software by doing it and helping others do it.
software by doing it and helping others do it.
Through this work we have come to value:
Through this work we have come to value:
•Individuals and interactions
Individuals and interactions over processes
over processes
and tools
and tools
•Working software
Working software over comprehensive
over comprehensive
documentation
documentation
•Customer collaboration
Customer collaboration over contract
over contract
negotiation
negotiation
•Responding to change
Responding to change over following a plan
over following a plan
That is, while there is value in the items on the
That is, while there is value in the items on the
right, we value the items on the left more.”
right, we value the items on the left more.”
Kent Beck et al
Kent Beck et al

What is “Agility”?
What is “Agility”?
 Effective (rapid and adaptive) response to change
Effective (rapid and adaptive) response to change
 Effective communication among all stakeholders
Effective communication among all stakeholders
 Drawing the customer onto the team
Drawing the customer onto the team
 Organizing a team so that it is in control of the
Organizing a team so that it is in control of the
work performed
work performed
Yielding …
Yielding …
 Rapid, incremental delivery of software
Rapid, incremental delivery of software

An Agile Process
An Agile Process
 Is driven by customer descriptions of what is
Is driven by customer descriptions of what is
required (scenarios)
required (scenarios)
 Recognizes that plans are short-lived
Recognizes that plans are short-lived
 Develops software iteratively with a heavy
Develops software iteratively with a heavy
emphasis on construction activities
emphasis on construction activities
 Delivers multiple ‘software increments’
Delivers multiple ‘software increments’
 Adapts as changes occur
Adapts as changes occur

Extreme Programming (XP)
 The most widely used agile process, originally proposed
The most widely used agile process, originally proposed
by Kent Beck
by Kent Beck
 XP Planning
XP Planning
 Begins with the creation of “
Begins with the creation of “user stories
user stories”
”
 Agile team assesses each story and assigns a
Agile team assesses each story and assigns a cost
cost
 Stories are grouped to for a
Stories are grouped to for a deliverable increment
deliverable increment
 A
A commitment
commitment is made on delivery date
is made on delivery date
 After the first increment “
After the first increment “project velocity
project velocity” is used to help define
” is used to help define
subsequent delivery dates for other increments
subsequent delivery dates for other increments

 XP Design
XP Design
 Follows the
Follows the KIS principle
KIS principle
 Encourage the use of
Encourage the use of CRC cards
CRC cards (see Chapter 8)
(see Chapter 8)
 For difficult design problems, suggests the creation of “
For difficult design problems, suggests the creation of “spike solutions
spike solutions”—a design
”—a design
prototype
prototype
 Encourages “
Encourages “refactoring
refactoring”—an iterative refinement of the internal program design
”—an iterative refinement of the internal program design
 XP Coding
XP Coding
 Recommends the
Recommends the construction of a unit test
construction of a unit test for a store
for a store before
before coding commences
coding commences
 Encourages “
Encourages “pair programming
pair programming”
”
 XP Testing
XP Testing
 All
All unit tests are executed daily
unit tests are executed daily
 “
“Acceptance tests”
Acceptance tests” are defined by the customer and excuted to assess customer
are defined by the customer and excuted to assess customer
visible functionality
visible functionality

unit test
continuous integration
acceptance testing
pair
programming
Release
user stories
values
acceptance test criteria
iteration plan
simple design
CRC cards
spike solutions
prototypes
refactoring
softw
areincrem
ent
project velocity com
puted

Adaptive Software Development
 Originally proposed by Jim Highsmith
Originally proposed by Jim Highsmith
 ASD — distinguishing features
ASD — distinguishing features
 Mission-driven
Mission-driven planning
planning
 Component-based focus
Component-based focus
 Uses “
Uses “time-boxing
time-boxing” (See Chapter 24)
” (See Chapter 24)
 Explicit consideration of
Explicit consideration of risks
risks
 Emphasizes
Emphasizes collaboration
collaboration for requirements gathering
for requirements gathering
 Emphasizes “
Emphasizes “learning
learning” throughout the process
” throughout the process

adaptive cycle planning
uses mission statement
project constraints
basic requirements
time-boxed release plan
Requirements gathering
J AD
mini-specs
components implemented/tested
focus groups for feedback
formal technical reviews
postmortems
softw
areincrem
ent
adjustm
entsforsubsequent cycles
Release

Dynamic Systems Development Method
 Promoted by the DSDM Consortium (
Promoted by the DSDM Consortium (www.dsdm.org
www.dsdm.org)
)
 DSDM—distinguishing features
DSDM—distinguishing features
 Similar in most respects to XP and/or ASD
Similar in most respects to XP and/or ASD
 Nine guiding principles
Nine guiding principles
 Active user involvement is imperative.
Active user involvement is imperative.
 DSDM teams must be empowered to make decisions.
DSDM teams must be empowered to make decisions.
 The focus is on frequent delivery of products.
The focus is on frequent delivery of products.
 Fitness for business purpose is the essential criterion for acceptance of deliverables.
Fitness for business purpose is the essential criterion for acceptance of deliverables.
 Iterative and incremental development is necessary to converge on an accurate
Iterative and incremental development is necessary to converge on an accurate
business solution.
business solution.
 All changes during development are reversible.
All changes during development are reversible.
 Requirements are baselined at a high level
Requirements are baselined at a high level
 Testing is integrated throughout the life-cycle.
Testing is integrated throughout the life-cycle.

DSDM Life Cycle (with permission of the DSDM consortium)

Scrum
Scrum
 Originally proposed by Schwaber and Beedle
Originally proposed by Schwaber and Beedle
 Scrum—distinguishing features
Scrum—distinguishing features
 Development work is partitioned into “
Development work is partitioned into “packets
packets”
”
 Testing and documentation are on-going
Testing and documentation are on-going as the product is
as the product is
constructed
constructed
 Work occurs in “
Work occurs in “sprints
sprints” and is derived from a “
” and is derived from a “backlog
backlog” of
” of
existing requirements
existing requirements
 Meetings are very short
Meetings are very short and sometimes conducted without
and sometimes conducted without
chairs
chairs
 “
“demos
demos” are delivered to the customer with the time-box
” are delivered to the customer with the time-box
allocated
allocated

Scrum
Scrum
ScrumProcessFlow(usedw
ithperm
ission)

Crystal
Crystal
 Proposed by Cockburn and Highsmith
Proposed by Cockburn and Highsmith
 Crystal—distinguishing features
Crystal—distinguishing features
 Actually a
Actually a family of process models
family of process models that allow
that allow
“
“maneuverability
maneuverability” based on problem characteristics
” based on problem characteristics
 Face-to-face communication
Face-to-face communication is emphasized
is emphasized
 Suggests the use of “
Suggests the use of “reflection workshops
reflection workshops” to review the
” to review the
work habits of the team
work habits of the team

Feature Driven Development
 Originally proposed by Peter Coad et al
Originally proposed by Peter Coad et al
 FDD—distinguishing features
FDD—distinguishing features
 Emphasis is on defining
Emphasis is on defining “features”
“features”
 a
a feature
feature “is a client-valued function that can be implemented in
“is a client-valued function that can be implemented in
two weeks or less.”
two weeks or less.”
 Uses a
Uses a feature template
feature template
 <action> the <result> <by | for | of | to> a(n) <object>
<action> the <result> <by | for | of | to> a(n) <object>
 A
A features list
features list is created and “
is created and “plan by feature
plan by feature” is conducted
” is conducted
 Design and construction merge in FDD
Design and construction merge in FDD

Reprinted with permission of Peter Coad
Reprinted with permission of Peter Coad

Agile Modeling
Agile Modeling
 Originally proposed by Scott Ambler
Originally proposed by Scott Ambler
 Suggests a set of agile modeling principles
Suggests a set of agile modeling principles
 Model with a purpose
Model with a purpose
 Use multiple models
Use multiple models
 Travel light
Travel light
 Content is more important than representation
Content is more important than representation
 Know the models and the tools you use to create them
Know the models and the tools you use to create them
 Adapt locally
Adapt locally

software engineering notes for msc stude

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