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At XP2004 a couple of weeks ago Andy Pols and I presented our whitepaper, An Agile Approach to a Legacy System.

Basically it describes how we approached an intractable legacy app. By writing a new system that extracted its data from the old system, we were able to quickly develop new features to the customers, without comprimising the legacy system.

Over time, this strategy could be used to replace the legacy system with a brand new almost ‘greenfield’ application.

Abstract: We describe how a small, successful, self-selected XP team approached a seemingly intractable problem with panache, flair and immodesty. We rewrote a legacy application by delivering new features, a radically different approach to those previously applied. This proved to be a low cost, low risk proposition with a very high payoff for success. Most importantly it provided users with new functionality quickly that could never have been retrofitted into the legacy system. In the longer term it may give a migration strategy for replacing the legacy system.

Download (PDF)

When we presented this at the conference, we used an approach that we had used on the project to facilitate pairing. I hog the steering wheel when pairing, so I wrote a small java app that behaved like a chess clock. It has 2 dials, and counts down a specified amount of time one each. You click once to start it, and then when the time runs out you click it again and it swaps to the other clock and counts down that one.

When pairing we had it set at about 10 minutes. At the conference we had it set at 1 minute, and we took turns in speaking to the slides. We only had 20 minutes but we hit it spot on and managed to say everything we meant to. (Andy also blogged this here)

Here’s a screenshot of the clock:

This entry was posted on Monday, June 28th, 2004 at 11:29 pm and is filed under development. You can follow any responses to this entry through the RSS 2.0 feed. You can skip to the end and leave a response. Pinging is currently not allowed.