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Agenda
Theory
Practice
Understanding before doing
Beautiful code
Guessing the future
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Theory
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Lost in Terminology
Software metric primitives are non-isomorphic:
“defect”
“resource”
“programmer”
“time”
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Lost in Terminology
Entailment?I need help *FINDING*
my tail!
http://www.flickr.com/photos/efleming/237379205/
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60/60 Rule
Cost of softwareover entire lifecycle
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Understanding and Bugs
Causes of bugs:The greatest number of bugs
occur in requirements specification and design
Cost of repair:The greatest cost is incurred in correcting requirements bugs
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Three Fallacies
The Fallacy of Perfect Knowledge:It is possible to capture complete, non-conflicting requirements with sufficient attention to detail.
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Three Fallacies
The Fallacy of Perfect Knowledge:It is possible to capture complete, non-conflicting requirements with sufficient attention to detail.
Users generally do not know what is possible, do not agree among themselves and may not understand all aspects of their system.
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Three Fallacies
The Fallacy of the Big Round Ball:Requirements don’t change appreciably after delivery or can be controlled.
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Three Fallacies
The Fallacy of the Big Round Ball:Requirements don’t change appreciably after delivery or can be controlled.
Requirements change continuously as software ages. This should be seen as a benefit.
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Three Fallacies
The Fallacy of Perfect Execution:It is possible to create flawless code with sufficient attention to detail.
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Three Fallacies
The Fallacy of Perfect Execution:It is possible to create flawless code with sufficient attention to detail.
We need to admit that arbitrary logic is hard to verify in the general case, hard or impossible to fully test and, combined with inconsistent or changing requirements, hard to trace programmer intent.
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Practice
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(With apologies to S. Gross)
The Real World isSoft and Mushy
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A History of Silos
1970s 1980s 1990s
$ cat foo.txt | grep blah | sort
A neat little package Client-Server The Early Web
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The Next Great Leap
Web of Data
Extending theUniversal Client
Expanding theUniversal Connection
Providing theUniversal Database
Explaining the Logic
Ubiquitous,reusable applications
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Examples
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New Applications
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And More....
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Understanding Before Doing
Some material adapted from Kurt Akeley,General Manager, Microsoft Research Asia, 21 July 2006
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The Cost of Failure
“If you can’t code something, it is because you don’t understand it” -- Jon Butler
Sadly, the reverse is not true.
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Writing Facilitates Understanding
The process of writing is the process of refining one’s thoughts.
Refinement of thought applies to writing both words and code.
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“This, surely, is the secret of Lincoln’s eloquence. He not only read aloud, to think his way into sounds, but wrote as a way of ordering his thought.”
— Garry WellsIn Lincoln at GettysburgSimon & Shuster, 1992
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“Don’t worry if you don’t understand this book completely on the first reading. We didn’t understand it all on the first writing!”
— Erich Gamma, Richard Helm, Ralph Johnson, and John Vlissides (aka The Gang of Four)In Design Patterns, Addison Wesley, 1995
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Write Up
ResultsDone?
Research &
Develop
Yes
No
Stop
?
Write First
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Beautiful Code
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What Does Your CodeLook Like?
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A Hardware Analogy
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Another Hardware Analogy
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“Higher-level programming ... allows good programmers to write more beautiful code, and bad programmers to write stuff that's even uglier than it used to be.”
— Andy Oram & Greg Wilson (eds.)Beautiful Code, O’Reilly, 2007
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Creating Beautiful Code
Beauty counts“Omit needless words!” -- Strunk and WhiteDevelop a habit of refactoring for both
design and maintenanceThe art changes; keep up
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Guessing the Future
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Writing Business Applications
1970s 1980s 1990s 2000s
Code written
Dataformatted
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Same Data, Different Forms
HumanReadable
MachineReadable
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Getting to the Web 2.0+ Enterprise
Thanks to CBS Paramount Television. TM & Copyright © 2007 CBS Studios Inc.
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2000 3B
2001 6B
2002 12B
200324B
40,000 BCEcave paintings
bone tools
writingpaper
printing
electricity, telephone
transistorcomputing
Internet(DARPA) The web
GIGABYTES
2000 rich contentSource: UC Berkeley School of Information Management and Systems,Robert Steele, CEO OSS, Inc.
The Information Economy
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Don’t Focus on Code
Solve problems insteadStart thinking about information spacesNavigating
Creating
Extracting From
Extending
Abstraction, abstraction, abstraction
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