IMAGICA SERVICES

Operation

         

          A network based on the client–server model where multiple individual clientsrequest services and resources from centralized servers

          Strictly speaking, the term server refers to a computer program or process (running program). Through metonymy, it refers to a device used for (or a device dedicated to) running one or several server programs. On a network, such a device is called a host. In addition to server, the words serve and service (as noun and as verb) are frequently used, though servicer and servant are not. The word service (noun) may refer to either the abstract form of functionality, e.g. Web service. Alternatively, it may refer to a computer program that turns a computer into a server, e.g. Windows service. Originally used as "servers serve users" (and "users use servers"), in the sense of "obey", today one often says that "servers serve data", in the same sense as "give". For instance, web servers "serve [up] web pages to users" or "service their requests".

          The server is part of the client–server model; in this model, a server serves data for clients. The nature of communication between a client and server is request and response. This is in contrast with peer-to-peer model in which the relationship is on-demand reciprocation. In principle, any computerized process that can be used or called by another process (particularly remotely, particularly to share a resource) is a server, and the calling process or processes is a client. Thus any general purpose computer connected to a network can host servers. For example, if files on a device are shared by some process, that process is a file server. Similarly, web server software can run on any capable computer, and so a laptop or a personal computer can host a web server.

While request–response is the most common client–server design, there are others, such as the publish–subscribe pattern. In the publish–subscribe pattern, clients register with a pub–sub server, subscribing to specified types of messages; this initial registration may be done by request–response. Thereafter, the pub–sub server forwards matching messages to the clients without any further requests: the server pushes messages to the client, rather than the client pulling messages from the server as in request–response.

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Hardware requirement

       

          A rack-mountable server with the top cover removed to reveal internal components

Hardware requirement for servers vary widely, depending on the server's purpose and its software.

Since servers are usually accessed over a network, many run unattended without a computer monitor or input device, audio hardware and USB interfaces. Many servers do not have a graphical user interface (GUI). They are configured and managed remotely. Remote management can be conducted via various methods including Microsoft Management Console (MMC), PowerShell, SSH and browser-based out-of-band management systems such as Dell's iDRAC or HP's iLo.

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Operating systems

         

          Sun's Cobalt Qube 3; a computer server appliance (2002); running Cobalt Linux (a customized version of Red Hat Linux, using the 2.2 Linux kernel), complete with the Apache web server.

          On the Internet the dominant operating systems among servers are UNIX-like open source distributions, such as those based on Linux and FreeBSD,[10] with Windows Server also having a very significant share. Proprietary operating systems such as z/OS and macOS Server are also deployed, but in much smaller numbers.

          Specialist server-oriented operating systems have traditionally had features such as:

• GUI not available or optional

• Ability to reconfigure and update both hardware and software to some extent without restart

• Advanced backup facilities to permit regular and frequent online backups of critical data,

• Transparent data transfer between different volumes or devices

• Flexible and advanced networking capabilities

• Automation capabilities such as daemons in UNIX and services in Windows

• Tight system security, with advanced user, resource, data, and memory protection.

• Advanced detection and alerting on conditions such as overheating, processor and disk failure.

In practice, today many desktop and server operating systems share similar code bases, differing mostly in configuration.

 

Energy consumption

         

       In 2010, data centers (servers, cooling, and other electrical infrastructure) were responsible for 1.1-1.5% of electrical energy consumption worldwide and 1.7-2.2% in the United States. One estimate is that total energy consumption for information and communications technology saves more than 5 times its carbon footprint in the rest of the economy by enabling efficiency.