file in RESTful web service

Hi! How can I attach a zip file in my request/response?

Backup module: I have a web service that creates a zip file. And the I would need to attach the created zip file in the response.
Restore module: I have a zip file to be passed to the rest web service. I have seen a http addfile method but how will the web service read the zip file content in ws_create()?

Please advice.