Remote Procedure Call Protocol

NFS is implemented on a wide variety of machine types, operating systems, and network architectures. NFS achieves this independence using the Remote Procedure Call (RPC) protocol.

RPC is a library of procedures. The procedures allow one process (the client process) to direct another process (the server process) to run procedure calls as if the client process had run the calls in its own address space. Because the client and the server are two separate processes, they need not exist on the same physical system (although they can).

NFS is implemented as a set of RPC calls in which the server services certain types of calls made by the client. The client makes such calls based on the file system operations that are done by the client process. NFS, in this sense, is an RPC application.

Because the server and client processes can reside on two different physical systems which may have completely different architectures, RPC must address the possibility that the two systems might not represent data in the same way. For this reason, RPC uses data types defined by the eXternal Data Representation (XDR) protocol.