Hi guys,
I would propose to that instead of <antlib> calling ruper, the rupper people can provide a <ruperautoload> task (or whatever other name you want) that will do all the finding and downloading and then will invoque <antlib>.
If we do this, then we can concentrate here on the local <antlib> while someone else can take care of the external work.
Jose Alberto
Maybe you can register one or more handlers for missing/out-of-date libraries and people can choose their downloader appropriately. so the gumploader would download and build your dependencies, ruper just pull them from wherever.