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Sean Hull is a renowned author, speaker and advisor on MySQL & Oracle databases, web performance and scalability, EC2, Linux & Internet Architecture. He is the author of "Oracle & Open Source" O'Reilly, 2001, and speaks widely at conferences and forums. With 20 years of professional experience, he consults with large enterprises and startups in New York City and the San Francisco Bay Area. Sean is a DZone MVB and is not an employee of DZone and has posted 64 posts at DZone. You can read more from them at their website. View Full User Profile

Understand the High Cost of Technical Debt by Ward Cunningham

08.24.2013
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A week or two ago, I got into a conversation on Twitter about technical debt, and someone shared this superb video by Ward Cunningham (youtube). Here is Ward’s Interview website.

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Waterfall, agile, developer or operations, devops, managers, CTOs… everyone should watch this video, for it cuts to the heart of the challenges we face doing modern software development, in a fast paced and always changing environment.

Though it’s not mentioned in the video, I would argue using an ORM is an expensive form of debt, one that is improperly calculated by teams, managers & startups, and one that bites hard into future scalability. Stay tuned for a post about that!

Enough said, here’s the video.

Here’s the transcript of much of the dialog. Appologies for any typos…

1. Metaphors & Thinking

I became interested in the way metaphors influence the way we think

after reading George Lakoff & Mark Johnson’s Metaphors We Live By (Amazon).

An important idea is that we reason by analogy through the metaphors that have entered our language.

Related: 5 Things Toxic to Scalability.

2. Coining Debt Metaphor

I coined the debt metaphor to explain the refactoring we were doing on a product.

This was an early product done in smalltalk. It was important to me that we accumulate the learnings we did about the application by modifying the program to look as if we had known what we were doing all along. And to look as if it had been easy to do in smalltalk.

The explanation I gave to my boss, and this was financial software, was a financial analogy I called the debt metaphor and that said that:

[quote]
If we failed to make our program align with what we then understood to be the proper way to think about our fin objects, then we were going to continue to stumble on that disagreement which is like paying interest on a loan. -Ward Cunningham
[/quote]

Also: AirBNB didn’t have to fail when Amazon went down.

3. Need for Speed

With borrowed money you can do something sooner than you might otherwise, but until you pay back that money you will pay interest.

I thought borrowing money was a good idea. I thought that rushing software out the door to get some experience with it was a good idea. But that of course you would eventually go back and as you learned things about that software you would repay that loan by refactoring the program to reflect your experience as you acquired it.

Read this: Why generalists are better at scaling the web.

4. Understand the Burden

I think that there were plenty of cases where people would rush things soft out the door & learn things, but never put that learning back into the program. That by analogy was borrowing money thinking you never had to pay it back. of course If you do that you know say with your credit card, evemtually all your income goes to interest & your purchasing power goes to zero.

By the same token if you dev a program for a long period of time, by only adding features, and never reorganizing it to reflect your understanding of those features, then eventually that program does not contain any understanding and all efforts to work on it take longer and longer. In other words the interest is total. You’ll make zero progress.

Check out: How to hire a developer that doesn’t suck.

5. Achieving Agility

a lot of bloggers at least have explained the debt metaphor and confused it i think with the idea that you could write code poorly with the intention of doing a good job later. and thinking that that was the pirmary source of deb.t I’m never in favor of writing code poorly. But I am in favor of writing a code to reflect your current understanding of a problem even if your understanding is partial.

If you want to be able to go into debt that way by dev soft you odn’t completely understand, you’re wise to make that software reflect your understanding as best you can. So that when it does come tiem to refactor it’s clear what your thinking was when you wrote it. and making it easier to refactor it to what your thinking is now.

in other words the whole debt metaphor or lets say the ability to pay back debt, and make the debt metaphor work for your advantage depends upon you writing code that is clean enough to be able to refactor as you come to understand your problem.

i think that’s a good methodology it’s at the heart of extreme programming. the debt metaphor is an explanation, one of many explanations as to why extreme programming works.

Read our popular interview guides for candidates, managers & recruiters: MySQL DBAAWS Expert (Amazon Cloud) and Cloud Deployment & Automation Engineer.

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Published at DZone with permission of Sean Hull, author and DZone MVB. (source)

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