testing

On Forests and Trees

When an English speaker is drowning in details that make the big picture hard to see, she might complain, “I can’t see the forest for the trees.”

image credit: Miguel Virkkunen Carvalho (Flickr)

It’s an odd expression, partly ironic and partly humorous. When I hear it, I sometimes think of my sister, who, after moving from Indiana to Utah, complained that the mountains were getting in the way of her view. (Her tongue was firmly in her cheek… :-)

The expression also describes an important problem of software engineering–one that a lot of engineers don’t understand well enough. It’s a problem with generalization.
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My Bibifi Adventure

I’ve been involved in a learning experiment these past six weeks. Now that it’s winding down, I thought I’d reflect a bit on some themes that emerged.

For the past 9 months or so, I’ve been taking classes online from Coursera to complete a Cybersecurity specialization taught by the University of Maryland. I’ve learned about security and usability, various flavors of software vulnerability, secure integrated circuit design, digital watermarks, and encryption theory.

In early May I began the final class in the sequence–a capstone project where teams of students attempt to build secure software to match a spec, then try to break one another’s submissions with a combination of pen testing, static code analysis, fuzzers, and theory taught in our other security courses. The project is framed as an international coding/testing competition hosted on builditbreakit.org (hence the “bibifi” in the title of this post), and this May’s running of the contest includes several hundred very sharp participants from around the world.

Bibifi Scoreboard

Partial bibifi scoreboard, showing 5 of about 100 teams. I was on team “SEADA”. Net of score in buildit round minus bugs logged against code in breakit round shows current overall standings.

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Add some more extra redundancy again

It’s the season for coughs and sniffles, and last week I took my turn. I went to bed one night with a stuffy nose, and it got me thinking about software.

What’s the connection between sniffles and software, you ask?

Let’s talk redundancy. It’s a familiar technique in software design, but I believe we compartmentalize it too much under the special topic of “high availability”–as if only when that’s an explicit requirement do we need to pay any attention.

Redundancy can be a big deal. Image credit: ydant (Flickr)

Redundancy in nature

Mother Nature’s use of redundancy is so pervasive that we may not even realize it’s at work. We could learn a thing or two from how she weaves it–seamlessly, consistently, tenaciously–into the tapestry of life.

Redundancy had everything to do with the fact that I didn’t asphyxiate as I slept with a cold. People have more than one sinus, so sleeping with a few of them plugged up isn’t life-threatening. If nose breathing isn’t an option, we can always open our mouths. We have two lungs, not one–and each consists of huge numbers of alveoli that does part of the work of exchanging oxygen and carbon dioxide. Continue reading →

Flexibility is No Virtue

Vice is a monster of so frightful mien,
As to be hated needs but to be seen;
Yet seen too oft, familiar with her face,
We first endure, then pity, then embrace.

—Alexander Pope, Essay on Man

If I had a penny for every programmer that I’ve heard, proudly touting the flexibility of what they’ve built, I’d be a wealthy man. I might even be able to afford my teenagers’ car insurance. :-)

As a young coder, I took the implied excellence of flexibility for granted; after all, who wouldn’t want to be flexible?

Now I know better.

If your software can be installed and configured a hundred different ways, this is Not Good. It is a sign that you don’t know who your customer is, or what they want. If your programming language has nine separate functions that provide the same functionality, shame on its designers. If your UI presents users with oodles of choices and calls it a customer focus, go vomit into the nearest garbage can.

V22-Osprey — an unusually flexible aircraft. Photo credit: Sgt. Mike Fayloga (Wikimedia Commons)

I can already hear the protests, so let me pause here to admit Continue reading →