What's That Noise?! [Ian Kallen's Weblog]

« Claim Your Blog and... | Main | Google Earth on Mac... »

20060110 Tuesday January 10, 2006

Ramblings on the Tension between Simplicity and Extensibility

There is widespread frustration with standards that try to boil the ocean of software problems that are out there to solve. Tim Bray has a sound advice:

If you're going to be designing a new XML language, first of all, consider not doing it.
In his discussion of Minimalism vs. Completeness he quotes Gall's Law:
A complex system that works is invariably found to have evolved from a simple system that worked. A complex system designed from scratch never works and cannot be patched up to make it work. You have to start over with a working simple system.
The tendency to inflate standards is similar to software development featuritus. I'm oft heard to utter the refrain, "Let's practice getting above the atmosphere before shooting for the moon." The scope of what is "complete" is likely to change 20% along the way towards getting there. The basic idea is to aim for sufficiency, not completeness; simplicity and extensibility are usually divergent. Part of the engineering art is to find as much of both as possible.

On the flip side, where completeness is an explicit upfront goal, there are internal tensions there as well. Either building for as many of the anticipated needs as possible or a profound commitment to refactoring has to be reckoned with. The danger of only implementing the simplist thing without a commitment to refactoring is that expediency tends to lead people, particularly if they haven't solved that type of problem before, to do the easy but counter-productive thing: taking short cuts, cutting and pasting and hard coding random magic doodads. As long as there is a commitment to refactoring, software atrophy can be combatted. Reducing duplication, separating concerns and coding to interfaces enables software to grow without declining in comprehensibility. Throw in a little test-driven development and you've got a lot of the standard shtick for agility.

Even though there's a project at work that I've been working on mostly solo, it's built for agility. The build system is relatively minimal thanks to maven. The core APIs and service interfaces (which favors simplicity: REST) are unit tested and the whole thing is monitored under CruiseControl to keep it all honest. This actually saved us the other day when a collaborator needed additional data included in the API's return values. He did the simplest thing (good) but I promptly got an email from CruiseControl that the build was broken. I reviewed his check-in and refactored it by moving the code that was put in-line in the method and moving it do it's own. I wrote a test for the method that fetches the additional data. And then wrote one for the original method's responses to include the additional data. The original method then acquired a flag to indicate whether the responses should be dressed up with this additional data; not all clients need it and it requires a round-trip to another data repository, making it a parameter makes sense since the applications that don't need it are performance sensitive. Afterwards, the code enjoyed additional benefits in that the caching had granularity that matched the distibution of the data sources. Getting the next mail from CruiseControl that it was happy with the build was very gratifying. I need to test-infect my colleagues so they learn to enjoy the same pavlovian response.

Anyway. I'm short on sleep and long on rambles this morning.

There are times when simple problems are mired in seemingly endless hand wringing and you have to stand up to shout JFDI. The Java software world, like RDF theorists and other parochial ivory tower clubs, seems to have a bad case of specificationitus. There are over 300 JSR's. Do we need all of those? On the other hand, great software is generally not created in a burst of a hackathon. There's no doubt that when a project has fallen into quicksand, getting all parties around a table and getting it out is an important way to clear the path. Rapid prototyping is often best accomplished in a focused push. I like prototyping to be used as a warm up exercise. If you can practice getting lift-off on a problem and you can attain high altitudes with some simple efforts, you're likelihood of making it to the moon increases.

( Jan 10 2006, 07:59:45 AM PST ) Permalink


Post a Comment:

Comments are closed for this entry.