Open Network Computing (ONC) is an operating environment developed by Sun Microsystems that serves as an interface to all resources on a network. It is the model of distributed computing supported by most Unix environments.
In the transport-oriented layers 1 to 4, ONC computing uses the TCP/ IP, SPX/ IPX or OSI transport protocols. The transport services are accessed via the Transport Layer Interface( TLI). Of the application-oriented layers, only the application layer is used, namely for Remote Procedure Call( RPC) and the Network File System( NFS). This is used to handle files that are distributed across remote nodes. The transfer of the distributed files is done by Remote Procedure Call (RPC).