A client sends requests to a server, according to some
protocol, asking for information or action, and the server
responds.
This is analogous to a customer (client) who sends an order
(request) on an order form to a supplier (server) who
despatches the goods and an invoice (response). The order
form and invoice are part of the "protocol" used to
communicate in this case.
There may be either one centralised server or several
distributed ones. This model allows clients and servers to be
their function, e.g. fast server/cheap client.
Examples are the name-server/name-resolver relationship in
DNS, the file-server/file-client relationship in
NFS and
["The Essential Client/Server Survival Guide", 2nd edition,
1996].
(1998-01-25)