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smaller stories and the assignment of value and cost occurs again.
It is important to note that new stories can be written at any time.
Customers and developers work together to decide how to
group stories into the next release to be developed by the XP
team. Once a basic commitment (agreement on stories to be
included, delivery date, and other project matters) is made for a
release, the XP team orders the stories that will be developed in
one of three ways:
1.
All stories will be implemented immediately (within a
few weeks).
2.
The stories with highest value will be moved up in the
schedule and implemented first.
3.
The stories with highest risk will be moved up in the
schedule and implemented first.
After the first project release has been delivered, the XP
team computes project velocity. Project velocity is the number of
customer stories implemented during the first release. Project
velocity can then be used to:
1.
Help estimate delivery dates and schedule for subsequent
releases.
2.
Determine whether an over commitment has been made
for all stories across the entire development project.
As the development proceeds, customer can add stories,
change the value of an existing story, split stories, or eliminate
them. The XP team will reconsiders all the remaining releases
and modifies its plans accordingly to maintain efficiency.
b.
Design
According to Pressman (2010:75), XP design strictly
follows the KIS (keep it simple) principle. A simple design is
always preferred over a complex and excessive representation. In
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