ESDS Knowledge Base


Client Server Network Operating Systems

A server is either a software (a computer program) in the client-server model, or hardware (a computer), on which, software runs under this concept.

A server (software) is a program with another program, the client communicates to procure.

A server (hardware) is a computer on which it run one or more server (software).

As the server hardware is in the jargon, the term Host is used. For the server as a software-term, there is no other name. The ambiguity of the term server is further explained and discussed in the following section.


History of the server-term

When the first server was programmed, they were the computers on which they are installed, referred to as a host. At that time, they were almost exclusively hosted special powerful computer ( mainframe ). With the increasing power of standard computers certain server services could also be provided by them and thus came into the light of a broader public.

The ambiguity present in some cases leads to confusion because the name server is often used in a form in which for the layman, it is especially difficult to see whether it is the hardware or software.

Evolution of host and server

The term host is in the computer since 1960s in connection with mainframes or mid-range systems and there usual time-sharing or multi-user-operating systems used. These systems are highly structured and essentially consist of a central processing unit, which is also known as the host and all the “intelligence” of houses, and the “dumb” terminals, which are only used as user devices in the workplace and in practice only for input and output of data are used.

In the Unix environment, differentiation at this time is clear, here are (usually graphical) workstations and workstation operating systems and their software (mostly console-based) distinction servers and server operating systems and associated software. However, by now are both expressions – at least colloquially and in connection with hardware – practically synonymous.

Server as a term for software / client-server concept

A server is a program that is offering services. As part of the client-server model , a different program, the client (customer), use this service. The server is ready to respond at any time to contact a client. The rules of communication (format, call the server and the meaning of exchanged between server and client data), called protocol and are each defined for a service.

In general, the concept can be extended to a group of servers that offers a set of services. Examples: mail server (extended) web server, application server, database server.

In practice, since servers usually collected run on specific machines, it has become common to refer to this computer as a server itself. The same examples: mail server, web server or application server.

Server as a term for hardware

The term server as hardware is used:

When referring to a computer whose hardware is designed for server applications, and partly by specific service areas (eg, high I / O throughput, large memory, many CPUs , high reliability, yet insignificant graphics performance).

  • Server farm
  • Server Rack
  • Blade Server

The monitoring and maintenance of a server is an important activity in any organization. Frequently used come between so-called network monitoring systems.


Virtual Server

The simplest case of a server is the one where on a host server software is installed.

If the performance of a single host is not sufficient to cope with the tasks of a server, you can connect several hosts to form a composite, which is also called computer cluster. For this purpose, a software is installed on all hosts that causes this and represents clusters towards the clients as a single server.

Dedicated Servers

A dedicated server is a server that is intended for a network service or more permanently operated services, and not for everyday tasks (Workstation) is used. In marketing, the term is used to suggest to the customer exclusivity.

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