Don't know if this is practicable, but check out SOAP::Lite. Use it to export your module (GDBM_File or whatever). Then in the client connect with +autodispatch, the class will then be available to your code, and tie should work as well.

One problem. GDBM_File and such are stateful modules, while SOAP servers generally expect to be stateless, although setting up a dedicated server with SOAP::Transport::HTTP might do the trick.