drools-mode.el provides an Emacs mode for editing Drools source files.
It has been tested on GNU Emacs 22.2 running on Windows Vista. I have used it to view and format all the .drl and .dslr files in the Drools 4.0.7 examples available from the Drools downloads page.
It is available as the project pdorrell/rules-editing-mode on GitHub.
A sample file my-drools.el shows how it can be used.
drools-mode.el (and my-drools.el)
Features provided are: