I need to do a client-server application, the client will be made with python-gtk,
all procedures will be on server-side to free the client of this workload. 
So i did search on google about client-server protocols and i found that CORBA and RPC are closer from what i had in mind, BUT also i want to made this app ready to accept web and mobile clients, so i found REST and SOAP.
From all that reading i found myself with this doubts, should i implement two different protocols, one for gtk-client (like RPC or CORBA) and another for web and mobile (REST or SOAP)?
Can i use REST or SOAP for all?
Use REST.  It's the simplest, and therefore the most widely accessible.  If you really find a need for SOAP, RPC, or CORBA later, you can add them then.
What protocol to use in client-server app communication with python?