Practical UNIX and Internet Security, 3rd Edition

Remote Procedure Call (RPC)

The fundamental building block of all network information systems is a mechanism for performing remote operations. Abstractly, this can be done via either messages or procedure calls; systems have been developed using both paradigms, and the capabilities are equivalent. Sun’s software engineers chose to use the abstraction of procedure calls. This mechanism, usually called RPC, allows a program running on one computer to more or less transparently execute a function that is actually running on another computer.

RPC allows programs to be distributed so that a computationally intensive algorithm can be run on a high-speed computer, a remote sensing device can be run on another computer, and the results can be compiled on a third. RPC also makes it easy to create network-based client/server programs. The clients and servers communicate with each other using remote procedure calls.

The RPC system was developed by Sun Microsystems for use with NIS and NFS. Sun’s RPC uses a system called XDR (external data representation) to represent binary information in a uniform manner and bit order. XDR allows a program running on a computer with one byte order, such as a SPARC workstation, to communicate seamlessly with a program running on a computer with an opposite byte order, such as a workstation with an Intel x86 microprocessor. RPC messages can be sent with either the TCP or UDP IP protocols (currently, the UDP version is more common). After their creation by Sun, ...