Post on 29-Nov-2014
description
Agile development
Extreme Programming (XP)
Abder-Rahman AliM.S.Software Engineering
DePaul CTIabder.rahman.ali@gmail.com
Just before we begin…
Agile development is a:
Software development process model.
.
Software development Process
Task (1)
Task (2)
Task (3)
.
.
.
Task (n)
Goal HIGH QUALITY SOFTWARE
Action
In other words…
THE ROADMAP THAT YOU FOLLOW
Software development Process Models
Nature of SoftwareC
hange
Change in what?
• Software being built (i.e. requirements).
• Team members.
• New technology appearing.
Implications…
• Change is the HEART of software.
• Support for changes should be built in everything we do in software
So, what is Agility?
A rapid and effective response to change.
So, what is Agility?
Effective communication among stakeholders.
So, what is Agility?
Drawing the customer into the team.
This yields to…
Rapid & incremental delivery of software.
An Agile team…
A team that is able to appropriately to changes.
Extreme Programming (XP)
PlanningDesign
Test
Coding
Release
The XP Process
The most widely used Agile process, and it is originally proposed by Kent Benck.
Planning
Design
KIS Principle
We just want the design to provide an implementation guidance for the story as it is written---nothing less, nothing more.
Don’t try to design extra functionality because you assume it will be required later.
Design
CRC Cards
ClassResponsibility Collaborator
Design
Spike Solutions
1- A design problem occurs.
2- Create a PROTOTYPE of that portion of the design.
3- Implement and evaluate the prototype.
Intent:
To lower risk when true implementation starts.
Design
Refactoring
Changing a software system in such a way that:
1- The internal structure is improved.
2- The external behavior is not altered (not changed).
Design occurs CONTINUOUSLY as the system is constructed.
Also means:
Testing
TEST FIRST
Testing
Unit tests are written before the code.
Tests are run to ensure that our software fails.
A good test case is one that ensures that the software fails.
Test is rerun until it passes.
Testing
All unit tests are executed daily.
This can raise warning flags early if things are going wrong.
Testing
Acceptance tests (customer tests):
They are specified by the customer.
They focus on the overall system features and functionality that are visible and reviewable by the customer.
They are derived from user stories.
Testing
Fixing small problems every few hours takes less time than fixing huge problems just before the deadline.
Fact:
Coding
Pair P
rogramm
ing
Coding
Two people work together at one computer to create code for a story.
This provides a mechanism for real-time problem solving and real-time quality assurance.
Keeps the developers focused on the problem at hand.
As pair programmers complete their work, the code they develop is integrated with the work of others.
Coding
ROI
Coding
ROI
Release
Project Velocity
The number of stories that we performed in this release.
When to use XP?
Dynamically changing requirements.
Risky projects.
Small development groups (up to 100).
Non-fixed price contract.
XP Rules…
Planning• User Stories• Release Planning• Small Releases• Measure Project Velocity• Divide project to iterations• Iterations Planning• Move People around• Stand up meeting
Designing• Simplicity• CRC cards• Spike solutions• Refactor
XP Rules…
Coding• Customer available• Code standards• Test-Driven• Pair Programming• Sequential change integration• Integrate often• Collective code ownership• Don’t optimize early• No overtime
Testing
• Unit test everything• All tests pass before release• Bug == new test• Acceptance tests
We Must Ask Ourselves…
Do we need Agile or any other
Software Development Process
models in our lab?
Questions?