My question to the Drupal community is: which is easier to bridge (Java or C++) to PHP (and specifically to Drupal)?
Writng a PHP extension is probably easier in C. Insofar, I have not seen any Java extension.
My vote is for Java, as I can distribute the (GPL'd) bytecode more easily than pre-compiled C++ binaries.
and you make Java mandatory on the server. That's not a good idea.
On a more general note, do any modules currently require php extensions that are not in PEAR? If so, how do they handle getting the module compiled and installed.
Very few if any module require any PHP extension which is not in the PHP core. Some reuqire a few scripts that are in PEAR like simpletest, but that's rare. But scripts are not extensions. Regards NK