About clients and servers

SCO networking is based on the ``client-server'' model. In its simplest form, a ``client'' is a program that requests a service and a ``server'' is a program that provides a service. In a networked environment, client programs frequently issue RPCs (Remote Procedure Calls) to request that an operation be performed; a server responds to the RPC by executing procedures to perform the operation and sending a response to the client. The terms may also refer to machines; ``server'' may refer to a host whose files or services are made available through RPCs, and ``client'' to the requesting host.

The implications of the terms ``client'' and ``server'' may vary in specific networking components. The following table summarizes some of these variations.

Table 1-1 Examples of client-server implementations in SCO networking components

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 Component     Client             Server
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 DNS           any program that   any program that
 (Domain       queries for host   responds to
 Name          names and          queries for host
 Service)      addresses          information
 --------------------------------------------------
 NFS           any host           any host that
 (Network      requesting that    ``exports'' file
 File          a remote file      systems for
 System)       system be          remote mounting
               mounted locally
 --------------------------------------------------
 NIS           any host that      any host that
 (Network      requests NIS-      fulfills requests
 Information   managed            for NIS-managed
 Service)      information        information
               across the
               network
 --------------------------------------------------
 SNMP          also called        also called
 (Simple       ``management       ``agent''; any
 Network       station''; any     program that
 Management    program that       responds to
 Protocol)     queries for        queries from a
               system status      management
               information from   station
               a remote system