- This article is about computer servers. For the food service use, see Waiter.
A server in computing is:
- The term is now also used to mean the physical computer on
which the software runs. Originally server software would be located on a mainframe computer or minicomputer. These have
largely been replaced by computers built using a more robust version of the microprocessor technology that is used in personal computers, and the term "server" was adopted to describe microprocessor-based machines designed
for this purpose.
Usage
Sometimes this dual usage can lead to confusion, for example in the case of a web server. This term could refer to the machine which stores and operates the websites, and it used in this sense by companies offering commercial hosting facilities. Alternatively, web
server could refer to the software, such as the Apache HTTP
server, which runs on such a machine and manages the delivery of web page components in response to requests from web browser clients.
Server hardware
A server computer shares its resources, such as peripherals and file storage, with the users' computers, called clients, on a network. It is possible for a computer to be a client and
a server simultaneously, by connecting to itself in the same way a separate computer would.
Many new devices now come with server capabilities. The X-Internet, Web Services, and Microsoft's .NET initiative all
work to make even the smallest system a server.
Many large enterprises employ numerous servers to support their needs. A collection of servers in one location is often
referred to as a server farm. It is possible to configure the machines to
distribute tasks so that no single machine is overwhelmed by the demands placed upon it (called "load balancing"), and this is
often done for hosts that expect tremendous amounts of activity. The terminology can be even more confusing in this case because
the client (or user) will connect to a remote host to access the server application, and that server application may need to
access other server software and/or another server machine.
Due to the continual demand for ever more powerful servers in ever decreasing spaces, companies such as IBM have developed
higher density configurations, the most notable of which is known as the "blade server". Blade servers incorporate a number of
server computers - sometimes as many as nine - each housed inside a high-density module known as a "blade", within the space
typically occupied by a single computer.
The rise of the microprocessor-based server was facilitated by the development of several versions of Unix to run on the Intel microprocessor architecture, including Solaris, Linux and FreeBSD. The Microsoft Windows series of operating systems also now includes server versions that support multitasking and other features required for servers, beginning with Windows NT.
X Window server
The X Window System can cause some confusion in the definition of
servers and clients. One might expect that the "server" in X would be the computer in which individual programs are running. In
reality, an X server provides access to computer input and output devices, such as monitors, keyboards, and mice. Programs that
are running in an X environment connect to the server to gain access to the hardware. In most situations, both the X server, and
the X clients (programs) reside on the same computer, but X allows for situations where clients can be running on multiple
computers that are miles away.
Historical note
Mainframes and minicomputers were originally accessed using dumb
terminals, which were unable to carry out any significant processing. This largely ended with the widespread use of personal computers by users.
See also
External links
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