Extreme programming (xp)

Agile Extreme

programming

XP

Agenda

• Introduce team

• Agile method(brief)

• XP history

• XP with other methods

• XP features

• XP release cycle

• XP principles

• XP values

• The Phases of XP

• Requirements scenarios

• XP testing

• XP advantages and disadvantages

• summery

Team members

• Mahmoud Sammy NoorEdeen

• Mohamed Abdelrahman

• Yasmeen Magdy

• Yara Osama

• Hend Ramadan

Agile method

• Focus on software rather than it’s design &

documentation(Working software over comprehensive documentation)

• Involve customer in development approach

• Individuals and interactions over processes

• and tools

• Rely on incremental approach(change over plan)

• Deliver software quickly to customers

Agile method continue…

• Not fit for larger projects

• Rely on team members understanding

aspects of system without documentation

• All development stages are

interleaved(متداخله)

8

Cost of Errors Increases Through a Project’s Lifetime

Project Phase

Cost

of E

rrors

Extreme Programming (XP)

Features• 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.

.

• The project is divided into iterations.

(Divide your development schedule into about a dozen عشرات iterations of 1 to 3

weeks in length. One week is the best choice even though it seems very

short. Keep the iteration length constant through out the project)• Don't schedule your programming tasks in advance. Instead have

an iteration planning meeting at the beginning of each iteration to plan

out what will be done

XP principles

Incremental planning

Test-first development

Simple design

Small releases

RefactoringContinuous integration

Collective ownership

Pair programming

Sustainable pace

Incremental planning

(requirements are recorded on

story cards and determined by

time and priority)

Small releases

The minimal useful first

• simple design

Test first

development

All developers are expected to refactor the code continuously as soon as

possible code improvements are found (i.e. put comments)

.

Developers work in pairs checking each

other work and provide support to

always do the code work

The pairs of developers work on all areas of the system, so

that no islands of expertise develop all developers take

responsibility for all the code any one can change any thing

Collective ownership

MetaphorNames within code and other work artifacts are chosen to be descriptive of the system being created.

Coding StandardEach team member follows the team standard for format and appearance of the artifacts.

Whole TeamThe team works together in a lab space or open area where collaboration and communication are maximized.

As soon as the work on task is complete , it is integrated into the whole

system

Large amount of

overtime are not

acceptable

Sustainable pace

On-site customer(representative of the end user of system)

The Values of Extreme

Programming

The Values of Extreme Programming

• Simplicity:

do what is needed and asked for, but no more

• Communication:

Everyone is part of the team and we communicate face to face daily

• Feedback:We demonstrate our software early and often then listen carefully and

make any changes needed

• Respect

Everyone gives and feels the respect they deserve as a valued team

member.

• Courage

We will tell the truth about progress and estimates.

Difference between Values and

practices• Values are more important than practices

aspect that can change to adapt to people (people over

processes)

• they are really a part of the methodology.

The Phases of XP

Phase description

Exploration Project inception, high-level user requirements, technical

prototyping

planning Prioritization of work , break down into releases and first plan

iterations Testing and development of the system includes iterations

planning

Where low level work break down occurs.

End users may work here at refining interface ensuring usability

productionizing Deployment of software into the customer’s production

environment

maintenance Ongoing maintenance ,patches and enhancement

Requirements scenarios

Requirements scenarios

Continue…

Customer

making decisions on requirements

User requirements are

expressed as scenarios or user

stories.

The customer chooses the

stories based on their priorities and

the schedule estimates.

the development team breaks them

down into implementation

tasks

XP and change

• software engineering is to design for

change

• it proposes constant code improvement

(refactoring) to make changes easier when

they have to be implemented.

XP testing features

Test-first development

User involvement in test development and validation

.

Automated test harnesses are used to run all component tests each time that a new release is

built.

Incremental test

development from

scenarios

XP testing difficulties

XP testing difficulties

continue..• Programmers prefer programming to testing and

sometimes they take short cuts when writing tests.

• Some tests can be very difficult to write incrementally

• It difficult to judge the completeness of a set of tests.

Although you may have a lot of system tests, your test

set may not provide complete coverage

XP advantages

• Individuals are not held responsible for problems with the

code. Instead, the team has collective responsibility for

resolving these problems.

• It acts as an informal review process because each line

of code is looked at by at least two people.

• It helps support refactoring

XP disadvantages

• You may have difficulty to get many developers

accept this practice

• Your customers may be busy

• XP is code centric rather than design

centric development(not fit for large

projects)

summery

notice

• Note that CRC not in XP

• In the summery slide

Extreme programming(XP)

Reference• http://www.extremeprogramming.org

• http://www.xprogramming.com/xpmag/wha

tisxp.htm

• http://www.agilemanifesto.org/

• http://www.poppendieck.com/• The Pragmatic Programmer: From Journeyman to Master,

by Andrew Hunt and David Thomas

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