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Archive for the ‘Agile Software Devevelopment’ Category

Encouragement for the new craftsman

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Do you now bear responsibility for the architecture of some code? I’d like to talk just with you.

I’d like to say that I think it’s really important to “listen and then lead”. You’re responsible to the customers of your code for its quality, and you’ll get a lot of pressure to “just do this” or “just do that”. The processes you put in place, to control the quality of contributions, are for the benefit of its users and the code as a whole—to maximize usefulness, not necessarily to maximize development.

Sometimes it’s okay, even necessary, to inconvenience a few people (including the contributors) in order that you don’t fail an even larger number of people. You’re not (at least I wasn’t) able to please everyone, and trying to do so can easily cause harm, both short term (immediate bugs) and long term (technical debt and bad architecture). It’s your, just your, job to balance all this and do what’s right overall, and it’s very much a judgement call.

Some of this might be replaced by a change control board’s decisions, but if you go that route, then you must have a change process that everyone follows, regardless of the demands of the moment. Some people are really slick and sophisticated in getting what they want, especially when it doesn’t hurt them if they end up creating a problem. (Heh, the more I reread that the more it sounds like parenting.)

I found I had to be confident enough to implement decisions and defend them, but flexible enough to shift policy and correct errors. On the plus side, I think these skills will help move you past your current position, and help you control the direction in which your career heads.

You’re doing pretty well if you don’t instantly take sides in conversation on the merits, which is better than I sometimes do. Even if you’re slow making decisions—and there is so much to learn—a little slow is ok, since it gives a chance for more reflection and more mature ideas. Don’t be afraid to be wrong: if you never make mistakes, never make a bold architectural decision, then you’re playing it too safe, and you could probably be replaced with a small shell script.

Take care and good luck!

Agile practice one-liners, and Alexander on refactoring

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A few one-line descriptions of Agile practices, because I feel they get to the heart of each.

Iterative development with feature teams: a few developers complete the development cycle (refactor, code, integrate, build, and test), for each of a few features, in two weeks to two months.

Refactoring: instead of a static, outdated architecture, rework the codebase with each feature.

Test-driven development: write tests of functionality for user stories, then write code to pass these tests.

Pairing and collective ownership: two developers introduce fewer errors to review and test for, and many developers distribute knowledge of the code.

Frequent integration: merge and build new changes at least daily, test at least weekly.

Automated regression test: collect all test cases into push-button test suites, run shortly after each deliverable build.

I also found a passage on refactoring from an OOPSLA keynote by Christopher Alexander:

It turns out that these living structures can only be produced by an unfolding wholeness. That it, there is a condition in which you have space in a certain state. You operate on it through things that I have come to call “structure-preserving transformations,” maintaining the whole at each step, but gradually introducing differentiations one after the other. And if these transformations are truly structure-preserving and structure-enhancing, then you will come out at the end with living structure. Just think of an acorn becoming an oak. The end result is very different from the start point but happens in a smooth unfolding way in which each step clearly emanates from the previous one.

Alexander, C. 1999. The origins of pattern theory: The future of the theory, and the generation of a living world. IEEE Software 16, 5 (Sept/Oct), 7182. http://doi.ieeecomputersociety.org/10.1109/52.795104

Written by catena

24 August 2007 at 1823

Baselining from Daily Builds

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Branching. Agile asks to trade baseline stability for ease of integration. Take the latest baseline available, make it work with your change, and merge it as soon as it passes your tests. This reduces the number of concurrent branches active at once, and therefore the amount of simultaneous variability in the code base. Developers will not need to rebaseline from the last official build to include changes already merged to the integration branch.

Testing. This does mean that problems are more likely to be merged and affect others, so automated unit testing helps avoid defects not due to the interaction with other components. Merging a change sooner gives it more second-order testing with other components before major builds, which increases the likelihood that interaction problems will be found before they can delay a release.

Quicker feedback about integration problems refocuses a developer’s attention on a change sooner, while the developer is still thinking about the problem, instead of at the next major build after a developer has moved on to other issues.

Written by catena

5 September 2006 at 1538