How can I upload a file generated by Natural RPC server sess

Hi everyone,
I just transform a legacy Natural application to a modern application using EntireX Communicator. The legacy application download to PC a workfile using Entire Connection emulation so what can I do to keep this functionality under EntireX Communicator.
The Natural subprograms runs on a UNIX machine and the Web Server runs on a Windows machine.
Thanks in advanced I really appreciate your help.