My work on the PigIron open source project is focussed on a Java interface to z/VM SMAPI so that eventually GUI or Web administrative and user applications can be coded in open source so you can run your little ol' mainframe from your desktop or browser.
But imagine testing such code!You're not just testing the code, you're formatting disks and creating user accounts and other such bedeitfulle system objects on a mainframe while you are testing! As the Wicked Witch of the West said, "These things must be handled very carefully ..."
Luckily, BSF4Rexx exists which enables the marvellously easy-to-use, tragically underappreciated open source ObjectRexx language to script Java classes in ObjectRexx syntax. Bingo! In a few days I had a testing framework which included all PigIron's classes with default test cases (which I'm now expanding upon in trunk).
Then driving home from work, I had the "D'oh" moment. Whack! I had written a general-purpose ObjectRexx interface to z/VM SMAPI that provably works and is easy to use, especially in the Rexx-aware world of mainframing which constitutes PigIron's primary (only conceivable) audience.
I'm polling my target user group. The ObjectRexx interface may, in the end, be more useful to the mainframe+open-source community than the web/gui fu I set out to provide.