OSF DCE Administration Guide--Introduction

OSF DCE Administration Guide—Introduction
• Replication, which is the process by which copies of information are created and kept
consistent
1.1 Clients and Servers
DCE is based on the client/server model. A server is a machine or process that provides
a specialized service to other machines or processes. A client is a machine or process
that uses a server’s specialized service during the course of its own work. Distributed
applications consist of a client side that initiates a request for service, and a server side
that receives and executes that request, and returns any results to the client. For
example, a client can request that a file be printed, and the server where the printer
resides carries out that request.
More than one server process can reside on a single machine. Also, one machine can be
both a client and a server. For example, a machine can be a client for one DCE
component and a server for another.
Figure 1-1 shows a machine that is a name server for a client that issues a name request.
The same machine is a client for a file server.
Figure 1-1. Interaction of Clients and Servers
response
request
name
name
Machine 2Machine 1
client
name
Machine 3
server
file
response
file
request
file
name
clientserver
file
1.2 Remote Procedure Call
A Remote Procedure Call (RPC) is a synchronous request and response between a local
calling program and a remote procedure. An RPC begins with a request from a local
calling program to use a remote procedure. It completes when the calling program
receives all the results (or an error status or exception) from the procedure.
1.3 The Cell
The cell is the basic unit of administration in DCE. A cell usually consists of users,
machines, and resources that share a common purpose and a greater level of trust with
each other than with users, machines, and resources outside of the cell. Members of a
1− 2 Tandem Computers Incorporated 124244