I second that; from my own experience: for easy integration from the java-side use SOAP; I guess the C/C++ side will have a useable SOAP implementation too. Besides SOAP::Lite are a whole bunch of modules on CPAN waiting to ease your pain in implementing the middleware.
SOAP has a bit more to offer compared against XMP::RPC, is nevertheless easy to handle and as good a standard as any other xml-based standard I've seen ;).
regards,
tomte
An intellectual is someone whose mind watches itself.
-- Albert Camus