[codeduck]

I'm surprised this isn't a standard base pattern in languages, to be honest. Apache's commons-logging library was a standard part of enterprise java placements for many years, and only started to go away when Log4J came along.

[lmz]

Log4j is one of the possible backends for commons logging (and was basically the reason for it - choosing between log4j and the built-in java logging). I think you mean SLF4J?

[codeduck]

I may be remembering it wrong, but I think log4j only became a commons logging backend several years after it became mainstream; before that I remember the two being entirely different and no interchangeable. It's a long time ago!