There it is. All that code. And you weren't responsible for its development. That fact alone is normally enough for most individuals to berate the code as flawed and unmanageable. But once past the reflex response, there may actually be a problem. Software that you didn't develop, and especially code that has evolved over a long period of time, is never a green field. The code itself is just the tip of an iceberg that includes history, politics, anthropology, and economics, but rarely any post-enlightenment reasoning.
How do you get your head around this stuff? How do you work with it? How do you move it forward without being so busy breaking eggs that you never have time to make the omelet? This tutorial takes a stroll through some of the issues plus some of the tips and tricks that might help out. There is no big vision and no technology sell. Indeed, one of the most significant pitfalls to be aware of is falling into the fashion trap, adopting the latest and greatest technology fad and declaring it to be the one true way forward. A succession of fashion parades is often responsible for putting some of the 'gac' into legacy.
This tutorial is targeted at programmers, managers, and other interested technical parties who find themselves working in or in contact with legacy code.
Kevlin Henney is an independent consultant and trainer. The focus of his work is in programming languages, OO, CBD, UML, patterns, and software architecture. He is a regular columnist for C/C++ Users Journal (online), Application Development Advisor (UK), and JavaSpektrum (Germany), and previously wrote columns in Java Report and C++ Report. He is also a member of the advisory board for Hillside Europe, the program chair for EuroPLoP 2003, and a popular speaker at conferences in the US and Europe.