NewClient returns a new client.

NewServer returns a new server.

NewServerWithCallback returns a new server, who upon completion of each RPC calls the given function.

ErrTooManyFiles is returned when too many file descriptors are mapped.

ErrUnknownMethod is returned when a method is not known.

Client is a urpc client.

FilePayload may be _embedded_ in another type in order to send or receive a file as a result of an RPC.

RemoteError is an error returned by the remote invocation.

Server is an RPC server.

Stopper is an optional interface, that when implemented, allows an object to have a callback executed when the server is shutting down.