In RHQ we use the Augeas library to do the configuration file parsing and updates for us in some of the plugins. Augeas in itself is pretty cool and the language for describing the structure of arbitrary configuration files and howto update them is pretty powerful. The only downside to using Augeas is that it is a C library and we therefore have to bind with it and use it more carefully so that we don’t leak its native resources that aren’t under control of JVM’s garbage collector.