Top 10 Soft ware
Engineering Concepts
(even in hard times)
Ed Yourdon
email: ed@yourdon.com
Website: www.yourdon.com
Blog: www.yourdonreport.com,
Twitter, Flickr, Facebook, LinkedIn: “yourdon”
Version 11.1, spring 2009
Slideshare.net version
green stuff = “internal” links to other pages in this document
blue stuff = “external” links -- i.e., URLs to pages on the Internet
Published under the GNU Free Documentation License (GFDL)

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Top Ten Eleven Items
Introduction
1. You can’t control what you can’t measure
2. Peopleware
3. Incrementalism
4. Iteration
5. Repair costs if defects leak downstream
6. Tradeoffs are non-linear
7. Reuse is important
8. Risk management is key
9. Consistency trumps brilliance + death-march
10. Don’t reinvent the wheel
11. Be transparent, conceal nothing (Kent Beck, Ron Jeffries, Ward Cunningham)
Conclusions
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Introduction
Why does this matter?
• We live in “interesting” times — which could continue for several years
• Business needs IT innovation, but also needs cost-cutting, “back to basics”
• See “Shift Happens” and “Did You Know?”
• Increasing complexity of systems, blah blah blah
• Why aren’t we using these concepts already? See my blog here and here for possible answers
• New issue (Web 2.0): users can control their own technology; revenge of the user
Most key soft ware engineering ideas are not new
But they never got implemented consistently
It’s not rocket science...
... but common sense isn’t common
Each new generation doomed to rediscover basics
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1. You can’t control
what you can’t measure
Lots of good books, including Tom DeMarco’s 1982 classic, “Controlling Soft ware
Projects,” and Paul Strassmann’s “The Squandered Computer”
Cultural/management issues more important than technical issues (see 1987
classic by HP’s Robert Grady & Deborah Caswell, “Soft ware Metrics: Establishing a
Company-Wide Program”
Core metrics: size, effort, defects, turnover
Soft metrics: morale, user satisfaction, etc.
System dynamics -- e.g., Brooks’ Law (start with Tarek Abdel-Hamid’s “Soft ware
Project Dynamics,” and Ray Madachy’s new book, “Soft ware Process Dynamics”)
New t wist: evidence-based scheduling
Take advantage of potential positive aspect of Heisenberg Uncertainty Principle.
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2. Peopleware
People are (and always have been) the biggest productivity factor in projects
Hire the best people you can, and emulate Google’s HR strategy
Question: would the brightest college graduates want to work for your company
(assuming they have a choice)?
Remember: most of them have never seen MS Outlook (and would be horrified if they did)
They assume everyone is blogging on Facebook and IM’ing on their iPhone/Android
They are staggered at the thought that anyone alive knows how to program in COBOL.
Give them decent office space; and minimize interruptions in the work environment
Avoid teamicide
“Peopleware”: see report from ICSE 2007 panel session on “Celebrating Peopleware’s
20th Anniversary, in Sep 2007 IEEE Soft ware. Also available here (free!) on my
blog.
See “Meet the Life Hackers,” from Oct 16, 2005 New York Times. Based on 1,000
hours of obser vations of t wo West Coast high-tech firms:
“Each employee spent only 11 minutes on any given project before being interrupted and whisked off
to do something else. What’s more, each 11-minute task was itself fragmented into even shorter
three-minute tasks, like answering e-mail messages ... And each time a worker is distracted from a
task, it takes 25 minutes, on average, to return to that task.”
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3. Incrementalism
(vs. “big bang” development)
Prototypes are invaluable; see “Object-Oriented
Rapid Prototyping,” by John Connell and Linda
Shafer
Use the “daily build” approach, and continuous
integration (thanks to Joe Chavez)
Promote change management, beware scope creep
and “scope churn”
See also the related concept, “economics of nudging.”
Here’s an article and a book: Nudge: improving
decisions about health, wealth, and happiness
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4. Iteration
See classic (i.e., “prehistoric”, pre-Internet) 1970 paper by
Win Royce, “Managing the Development of Large
Soft ware Systems: Concepts and Techniques”
Make small mistakes early, rather than big mistakes
later
Concept doesn’t have to be applied in an “ or nothing”
all
fashion
More recent OO version: “refactoring”
Use modern tools (Twitter, Wikis, etc) to support rapid,
collaborative iteration
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5. Repair costs increase if
efects “leak” downstream
Increases tenfold with each lifecycle phase
First documented by Barry Boehm in early
1980s
Agile crowd disagrees (see this great new
collection of agile links), emphasizes
continuous refactoring
But Boehm disagrees; may depend on project
size. See “Balancing Agility and Discipline: A
Guide for the Perplexed” (2004)
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6. Tradeoffs are Non-
Linear
Tradeoff bet ween people and time is a
3rd order polynomial
Capers Jones (p. 110 of “Estimating
Soft ware Costs”) says: Defects =
k*function-points**1.25
Hard to compute this in your head!
Need industrial-strength estimating
tools (e.g., SLIM, Costar) for rational
negotiation of non-trivial projects
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7 Reuse is important
.
Don’t just reuse code; also design, specs, processes,
plans, budget templates, teams, etc.
Web 2.0 version: API’s to support mashups
• Example: 6,000 apps developed with Facebook API in 5 months (from Mary
Meeker, at 2007 Web 2.0 Summit conference, p. 37 of presentation)
• See also OpenSocial API recently announced for all social net works (e.g.,
Myspace, Bebo, Hi5, etc.)
• Example: HousingMaps = Craig’s List + Google Maps. See also Google Maps NYC
interactive transit map mashup
• Important work being done now by IBM, Yahoo (Pipes) Microsoft (PopFly), etc
• 275 Flickr Mashups
• Funny example: Earth Sandwich
• Funny example: George Bush + U2’s “Sunday, Bloody Sunday”
• More amusement: Obama “1984” mashup
Again: technology less important than business/
cultural issues
Don’t ignore cost of reuse
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8. Risk Management is key
Common issue in failed projects; see Capers Jones’
“Assessment and Control of Soft ware Risks” (1994)
Shared risk management is crucial
Familiar techniques: R-Y-G list of top 10 risks
(example)
Remember: there are risks associated with process
improvement, as well as traditional soft ware
development projects.
See “Identifying and Managing Risks for Process Improvements,” by Joyce
Statz, Don Oxley, and Patrick O’Toole.
Again: main issues are cultural and political, not
technical (just as with 2007-2008 bank crisis)
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9. Consistency trumps
brilliance + death-march
Except in Silicon Valley (maybe)
Global recession will probably increase
the number of death-march projects for
at least the next few years... 
Instead, focus on approaches like SEI-
CMM, ISO-9000, six-Sigma, ITIL, etc, etc.
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10. Don’t Reinvent the Wheel
Best Practices (bottom-up!)
Worst Practices (233 blogs!)
SWBOK
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11. Be Transparent, conceal nothing
Thanks to Kent Beck, Ron Jeffries, and others via
Twitter dialogue on Feb 18, 2009
Kent Beck: “sw eng improves when we stop trying to
‘protect’ customers from the process & invite them to
view the sausage factory.”
Ron Jeffries: “Absolute agreement on concealment.
Conceal nothing. Transparency rules.”
Ward Cunningham: “Clean code can still have technical
debt and that might be good. Watch to understand why.”
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Conclusions
Technology is not the key issue
Fred Brooks: “there are no silver
bullets”
Margaret Mead’s “prefigurative
culture”
• See Michael Wesch’s commentary, “Vision of Students Today,” on how today’s Web 2.0
technology is affecting education for college students (also watch “the machine is (us)ing us”!
• Note Oct 3, 2007 announcement: UC Berkeley announces it will publish its university lectures
on YouTube
• You have no idea what the younger generation is thinking! See BRBOMGLOLROFLLMFAO and
“Google, A Girl, and the Coming Apocalypse.”
Don’t ignore new stuff — e.g.,
Chandler
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Published under the GNU Free Documentation License (GFDL)

Top 10 Soft ware
Engineering Concepts
(even in hard times)
Ed Yourdon
email: ed@yourdon.com
Website: www.yourdon.com
Blog: www.yourdonreport.com,
Twitter, Flickr, Facebook, LinkedIn: “yourdon”
Version 11.1, spring 2009
Slideshare.net version
green stuff = “internal” links to other pages in this document
blue stuff = “external” links -- i.e., URLs to pages on the Internet
Published under the GNU Free Documentation License (GFDL)