Unit -1.ppt

UNIT :1
Agile Software Development
Dr. N. N. Maltare
Government Engineering College, Modasa
Unit 1: Agile software development 1

COURSE OUTCOMES
Understand the practices and philosophies of
agile methods.
Examine the User experiences and User
designs with empirical and analytic evaluations.
Demonstrate the connection between UX design
with Agile software Development.
Use an agile UX design and Agile software
development method as per the need of the
project.
2

WATERFALL MODEL
Chapter 3 Agile software development 3

AGILE METHODOLOGY
• AGILE methodology is a practice that
promotes continuous iteration of
development and testing throughout the
software development lifecycle of the project.
• In the Agile model, both development and
testing activities are concurrent, unlike the
Waterfall model.
6

AGILE METHODOLOGY
The Agile software development methodology is
one of the simplest and effective processes to turn a
vision for a business need into software solutions.
Agile is a term used to describe software
development approaches that employ continual
planning, learning, improvement, team
collaboration, evolutionary development, and early
delivery.
It encourages flexible responses to change.
7

Agile manifesto
Our values:
 Individuals and interactions over processes and
tools
 Working software over comprehensive
documentation
 Customer collaboration over contract negotiation
 Responding to change over following a plan
That is, while there is value in the items on
the right, we value the items on the left
more.

Plan-driven and agile specification
separate
development
stages with
the outputs to
be produced
at each of
these stages
planned in
advance.
Not
necessarily
waterfall
model – plan-
driven,
incremental
development
is possible
Iteration within stage
Iteration of stage
User's full
agreement at
end, not before
code

Problems with agile methods
 It can be difficult to keep the interest of customers / users who are involved
in the process.
 Team members may be unsuited to the intense involvement that
characterizes agile methods.
 Prioritizing changes can be difficult where there are multiple stakeholders.
 Maintaining simplicity requires extra work.
 Contracts may be a problem as with other approaches to iterative
development.
 Because of their focus on small, tightly-integrated teams, there are
problems in scaling agile methods to large systems.
 Less emphasis on documentation - harder to maintain when you get a new
team for maintenance

Balance plan driven and agile
• Not great for Agile:
– What type of system is being developed?
• Plan-driven approaches may be required for systems that require a lot of analysis before implementation (e.g. real-time
system with complex timing requirements).
– What is the expected system lifetime?
• Long-lifetime systems may require more design documentation to communicate the original intentions of the system
developers to the support team.
– What technologies are available to support system development?
• Agile methods rely on good tools to keep track of an evolving design
– How is the development team organized?
• Many teams; Outsourcing ---> need design documents to control borders
 Culture or contract needs detailed specification
 Is rapid feedback from users realistic?
 Large scale, not co-located may require more formal communication methods
 Need high level programming skills - refactoring, work with little spec
 Outside regulation documentation requirements

Extreme programming
 A popular form of Agile
 Extreme Programming (XP) takes an ‘extreme’ approach to iterative
development.
 New versions may be built several times per day;
 Increments are delivered to customers every 2 weeks;
 All tests must be run for every build and the build is only accepted if tests run
successfully.
 Customer involvement means full-time customer engagement with the
team. - Specifications through user stories broken into tasks
 People not process : pair programming, collective ownership and a process
that avoids long working hours.
 Regular system releases. - release set of user stories
 Maintaining simplicity through constant refactoring of code.

The extreme programming release
cycle

The Parts and the Whole
Controller
Inspect
Set Target Adapt
• Clean Design & Code & Refactor
• User Stories - Late Elaboration
• Shared Code Ownership
• Test Driven Development…..
• Iteration Plan
• Daily Stand-Up
• Pair Programming
• Customer Reviews &
Feedback
• Retrospectives
• AutoTest…..
Sustainable pace
Collective Ownership with users
Minimal documentation for sprint

The Life of an Iteration

“Tell me how you will measure
me and I’ll tell you how I’ll
behave”
Transparency

A ‘prescribing medication’ story

Examples of task cards for
prescribing medication

Refactoring
 Programming team look for possible software improvements and
make these improvements even where there is no immediate need
for them.
 This improves the understandability of the software and so reduces
the need for documentation.
 Changes are easier to make because the code is well-structured
and clear.
 However, some changes requires architecture refactoring and this is
much more expensive.
RISK:
Changes the user does not test
Changes to working software break it

Examples of refactoring
Re-organization of a class hierarchy to
remove duplicate code.
Tidying up and renaming attributes and
methods to make them easier to
understand.
The replacement of inline code with calls
to methods that have been included in a
program library.

Test case description for dose
checking

Test automation
Automate tests (junit)
Run upon checkin
Difficulties:
Time constraints
Programmer preferences to not test
Test coverage

Pair programming
In XP, programmers work in pairs, sitting
together to develop code.
Common ownership
Knowledge spread
Informal review
Refactoring
Similar output to two people coding

Scrum
Project Manager's job: - Deliver needed
system on time within budget
The Scrum approach - manage the
iterations
There are three phases in Scrum.
 outline planning phase - general picture and
architecture
 Sprint cycles releasing increments of the
system.
 The project closure phase - final delivery,

The Scrum process

The Sprint cycle
Every 2–4 weeks (a fixed length).
1) Project team with customer: Look at
product backlog - select stories to
implement
2) implement with all customer
communication through scrum master
(protecting pgmr at this point)
Scrum master has project manager role
during sprint
Daily 15 min meetings

Scrum benefits
The product is broken down into a set of
manageable and understandable chunks.
Unstable requirements do not hold up
progress.
The whole team have visibility of
everything and consequently team
communication is improved.
Customers see on-time delivery of
increments and gain feedback on how the
product works.

Summary
Plan Driven (Ex: Waterfall) vs Incremental
(Ex: Agile )
Structure and benefits and downfalls
XP - an implementation of Agile - Power to the
Programmer
User story requirements
Test driven design with continual retest and
integration
Pair Programming
Refactoring encouraged

Unit -1.ppt

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