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[[Датотека:First-server-cern-computer-center.jpg|thumb| First [[WWW]] server located at [[CERN]] with its original sticker that says: „This machine is a server. DO NOT POWER IT DOWN!!”]]
У [[Рачунарство|рачунарству]], '''сервер''' ({{Јез-енгл|server}} — „послужитељ”) [[Рачунарски програм|рачунарски je програм]] или [[Рачунар|уређај]] који пружа функционалност другим програмима или уређајима који се названју [[Klijent (računarstvo)|клијенти]] ({{Јез-енгл|client}} — „клијент, муштерија”). Ова {{Међујезичка веза|en|Архитектура система|Systems architecture|архитектура}} назива се [[Model klijent—server|модел клијент—сервер]], те се једно опште рачунање дели на више процеса или уређаја. Сервери могу да пружају различите функционалности, често се називају „услугама”, попут дељења података или {{Међујезичка веза|en|Системски ресурс|System resource|ресурса}} између више клијената или извођење рачунања за клијента. Један сервер може служити више клијената, а један клијент може користити више сервера. Поступак клијента може се покренути на истом уређају или се може повезати преко мреже на сервер на другом уређају.<ref>{{cite book
|title = Windows Server Administration Fundamentals
|publisher = [[John Wiley & Sons]]
|location = 111 River Street, Hoboken, NJ 07030
|series = Microsoft Official Academic Course
|year = 2011
|pages = 2–3
|isbn = 978-0-470-90182-3}}</ref> Типични сервери су: {{Међујезичка веза|en|Сервер база података|Database server|сервери база података}}, {{Међујезичка веза|en|Сервер датотека|File server|сервери датотека}}, [[MTA|сервери е-поште]], {{Међујезичка веза|en|Сервер штампача|Print server|сервери штампача}}, {{Међујезичка веза|en|Веб-сервер|Web server|веб-сервери}}, {{Међујезичка веза|en|Сервер игара|Game server|сервери игара}} и {{Међујезичка веза|en|Сервер апликација|Application server|сервери апликација}}.<ref>{{cite book
|last1 last= Comer
|first1first = Douglas E.
|last2 = Stevens
|first2 = David L.
|title = Vol III: Client-Server Programming and Applications
|publisher = [[Prentice Hall]]
|location = Department of Computer Sciences, Purdue University, West Lafayette, IN 479
|series = Internetworking with TCP/IP
|year = 1993
|pages = 11d
|isbn = 978-0-13-474222-9}}</ref>
Client—server systems are today most frequently implemented by (and often identified with) the [[request–response]] model: a client sends a request to the server, which performs some action and sends a response back to the client, typically with a result or acknowledgement. Designating a computer as „server-class hardware” implies that it is specialized for running servers on it. This often implies that it is more powerful and reliable than standard [[personal computer]]s, but alternatively, large [[computing cluster]]s may be composed of many relatively simple, replaceable server components.
== Историја ==
The use of the word ''server'' in computing comes from [[queueing theory]],<ref>{{cite book |title=Desktop computers: in perspective |authors=Richard A. Henle, Boris W. Kuvshinoff, C. M. Kuvshinoff |publisher=Oxford University Press |year=1992 |url=https://books.google.com/books?id=g4krAAAAYAAJ&dq=server+%22queuing+theory%22 |page=417 |quote="Server is a fairly recent computer networking term derived from queuing theory."|pages=417}}</ref> where it dates to the mid 20th century, being notably used in {{Harvtxtharvnb|Kendall|1953}} (along with „service”), the paper that introduced [[Kendall's notation]]. In earlier papers, such as the {{Harvtxtharvnb|Erlang|1909}}, more concrete terms such as „[telephone] operators” are used.
In computing, „server” dates at least to RFC 5 (1969),<ref name="rulifson">{{cite IETF |title=DEL |rfc=5 |last=Rulifson |first=Jeff |authorlink=Jeff Rulifson |date=June 1969 |publisher=[[Internet Engineering Task Force|IETF]] |accessdate=30. November11. 2013}}</ref> one of the earliest documents describing [[ARPANET]] (the predecessor of [[Internet]]), and is contrasted with „user”, distinguishing two types of [[Host (network)|host]]: „server-host” and „user-host”. The use of „serving” also dates to early documents, such as RFC 4,<ref>{{cite IETF |title=Network Timetable |rfc=4 |last=Shapiro |first=Elmer B. |date=March 1969 |publisher=[[Internet Engineering Task Force|IETF]] |accessdate=30. November11. 2013}}</ref> contrasting „serving-host” with „using-host”.
The [[Jargon File]] defines „[http://www.catb.org/jargon/html/S/server.html server]” in the common sense of a process performing service for requests, usually remote, with the 1981 ([http://www.catb.org/jargon/oldversions/jarg110.txt 1.1.0]) version reading:
|-
|Virtual server
|Shares hardware and software resources with other virtual servers. It exists only as defined within specialized software called [[hypervisor]]. The [[hypervisor]] presents virtual hardware to the server as if it were real physical hardware.<ref>{{cite web |last1last=IT Explained |title=Server – Definition and Details |url=https://www.paessler.com/it-explained/server |website=www.paessler.com |language=en}}</ref> Server virtualization allows for a more efficient infrastructure.
|Any networked computer
|-
|Computers with a web browser
|}
Almost the entire structure of the [[Internet]] is based upon a [[client–server]] model. High-level [[root nameserver]]s, [[Domain Name System|DNS]], and routers direct the traffic on the internet. There are millions of servers connected to the Internet, running continuously throughout the world<ref>{{cite web|title=Web Servers|url=http://www.serverwatch.com/stypes/index.php/V2Vi|publisher=IT Business Edge|accessdate=July 31,. 7. 2013}}</ref> and virtually every action taken by an ordinary [[Internet]] user requires one or more interactions with one or more server. There are exceptions that do not use dedicated servers; for example [[File sharing|peer-to-peer file sharing]], some implementations of [[telephony]] (e.g. pre-Microsoft [[Skype]]).
== Потрошња енергије ==
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.<ref>{{cite news |url=https://www.nytimes.com/2011/08/01/technology/data-centers-using-less-power-than-forecast-report-says.html?_r=0 |title=Data Centers Using Less Power Than Forecast, Report Says |date=31 Jul 2011 |publisher=''[[NY Times]]'' |accessdate=18. Jan1. 2013 |first=John |last=Markoff}}</ref> One estimate is that total energy consumption for information and communications technology saves more than 5 times its [[carbon footprint]]<ref>{{cite web |url=http://www.smart2020.org/_assets/files/02_Smart2020Report.pdf |archive-url=https://web.archive.org/web/20101122051650/http://www.smart2020.org/_assets/files/02_Smart2020Report.pdf |dead-url=yes |archive-date=22. November11. 2010 |title=SMART 2020: Enabling the low carbon economy in the information age |date=6 Oct 2008 |publisher=''[[The Climate Group]]'' |accessdate=18. Jan1. 2013 |df= }}</ref> in the rest of the economy by increasing efficiency.
== Види још ==
== Додатна литература ==
{{категорија на Остави|Servers}}
{{refbegin|30em}}
* {{cite journal | authorlink = Agner Krarup Erlang | first = Agner Krarup | last = Erlang
| title = The theory of probabilities and telephone conversations | journal = NYT Tidsskrift for Matematik B | volume = 20 | pages = 33–39 | archiveurl = https://web.archive.org/web/20111001212934/http://oldwww.com.dtu.dk/teletraffic/erlangbook/pps131-137.pdf | archivedate archive-date=1. 2011-10-01. 2011. | url = http://oldwww.com.dtu.dk/teletraffic/erlangbook/pps131-137.pdf | year = 1909}}
* {{Cite journal
| last1 last= Kendall | first1first = D. G. | authorlink1authorlink = David George Kendall
| title = Stochastic Processes Occurring in the Theory of Queues and their Analysis by the Method of the Imbedded Markov Chain
| doi = 10.1214/aoms/1177728975
| volume = 24
| issue = 3
| pages = 338–354 | year = 1953
| pmid =
| pmc =
| 