1 march extreme programming. presentations tuesday campus tour sami says hawks thursday read2me...
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Presentations
Tuesday Campus Tour Sami Says Hawks
Thursday Read2Me UNCSET Oral Lab NetVis
If helpful, invite your client
Software Engineering Elaborated Steps Concept Requirements Architecture Design Implementation
Extreme Programming Unit test Integration System test Maintenance
What it is
Complete development process First code drop is 2-3 weeks after start Customer a part of the development
team Iterative development to the max Derive requirements with customer
through hands-on experimentation Agile methodology
XP Bills of Rights Developer has a right to
Clear requirements and priorities Determine how long a requirement will take to implement Revise estimates Always produce quality code
Customer has a right to An overall plan See progress in a running system Change requirements and priorities Be informed of changes to schedule and have input as to
how to adapt Cancel in the middle and still have something to show for
the investment
XP Bills of Rights Developer has a right to
Clear requirements and priorities Determine how long a requirement will take to implement Revise estimates Always produce quality code
Customer has a right to An overall plan See progress in a running system Change requirements and priorities Be informed of changes to schedule and have input as to
how to adapt Cancel in the middle and still have something to show for
the investment
XP Value System
Communication Focus on people, not documentation
Simplicity Of process and code
Feedback Mechanism to make useful progress
Courage To trust in people
People Most important factor in the quality of
software is the quality of the programmers If your life depended on a particular piece
of software, what would you want to know about it?
Bollinger (2001): that the person who wrote it was “both highly intelligent and possessed by an extremely rigorous, almost fanatical desire to make their program work the way it should.”
Knowledge Workers … prefer closed offices but communicate better
in open ones congregate in particular geographical areas move around in the course of their work collaborate concentrate work in the office communicate with people who are close by don't care about facilities gewgaws
Davenport, Why Office Design Matters 2005
User Stories
Use cases Written by customer Used for planning
Developers estimate by story Stories basis for iteration
Used to build acceptance tests Remember that correctness equals
meeting requirements
Spikes
Technology explorations Focus on high risk items Typically considered throw-away
code If not, needs to be agreed to by
the whole team
Release Planning
Focused on iterations Can be defined by function or date Other is adjusted accordingly (Actually four parameters: resources and quality
are the other two that can be used to adjust) Planning adapts as the project progresses
Project velocity is measured for each iteration Next iteration looks at planned vs. actual time
and adjusts accordingly Each iteration has its own plan
Developed at the beginning of the iteration
Iteration Scope of an iteration
Should cover all parts of the system Only add the functions that you need for the
current user story or stories Recommendation: 3 weeks Moving people around
Backup and training Code is owned by the whole team
Pair programming Re-factoring
Egoless Programming Weinberg 1971, The Psychology of
Computer Programming During the “cowboy” era
Observed that programmers needed to be team players Accept inspections and reviews Open to corrections and critiques
Ten Commandments (Lamont Adams) But pride of ownership is critical to quality
Pair Programming Two people working at a single computer Built-in backup and inspections Collaboration builds better code Mechanical model
One drives, the other talks Keyboard slides between the two
Logical model One tactical, the other strategic Both think about the full spectrum but bring
different perspectives
Pair Programming Experiments Typical numbers show the total
manpower consumed not very different Numbers range, but no more than ¼
additional manpower Implication: actual time is reduced Improved satisfaction also improves
productivity Williams et al, “
Strengthening the Case for Pair-Programming”
Re-factoring
Each iteration adds just the function needed
If you continue to add new functions every two weeks, code can get messy
Re-factoring is the cleaning up of the code at the end of the iteration
Critical to maintaining quality code (Also applies to the design)
Coding Rules The customer is always available. Code must be written to agreed standards. Code the unit test first. All production code is pair programmed. Only one pair integrates code at a time. Integrate often. Use collective code ownership. Leave optimization till last. No overtime.
Communications
Avoid unnecessary meeting Daily stand-up meetings
In a circle No chairs Everyone must attend
Minimizes other meetings Primarily informal as needed
When to Use XP
Types of projects High risk Poorly understood requirements
Team Small size: 2 to 12 Needs to include customer
Automated testing Timing issue
What Makes a Project XP Paradigm - see change as the norm, not the
exception, and optimize for change Values - honor the four values- communication,
simplicity, feedback, and courage- in your actions Power sharing - business makes business decisions
and development makes technical decisions Distributed responsibility and authority -
people get to make the commitments for which they will be held accountable
Optimizing process - you are aware of your software development process and when it is working and when it isn't, you are experimenting to fix the parts that aren't working, and you consciously acculturate new team members
Ward Cunningham, Ron Jeffries, Martin Fowler, Kent Beck
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