Web server
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The term web server can mean one of two things:
- a computer responsible for serving web pages, mostly HTML documents, via the HTTP protocol to clients, mostly web browsers;
- a software program that is working as a daemon serving web documents.
Connections to HTTP servers are made using web browsers.
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Common features
Although web server programs differ in detail, they all share some basic common features. Every web server program operates by accepting HTTP requests from the network, and providing an HTTP response to the requester. The HTTP response typically consists of an HTML document, but can also be a raw text file, an image, or some other type of document.
Path translation
Web servers translate the path component of a URI into a local file system resource. The URI path specified by the client is relative to the web server's root directory.
Consider the following URI as it would be requested by a client:
http://www.example.com/path/file.html
The client's web browser will translate it into a connection to www.example.com with the following HTTP 1.1 request:
GET /path/file.html HTTP/1.1 Host: www.example.com
The web server on www.example.com will append to its root path, which on a UNIX machine would commonly be /var/www/htdocs. The result will be the local file system resource:
/var/www/htdocs/path/file.html
The web server will then read the file, if it exists, and send a response to the client's web browser. The request will contain any appropriate headers and the file itself.
Historical note
The first webserver was developed at CERN to handle the huge telephone book. It ran on a black NeXT cube, which was also used to develop the first web browser, WorldWideWeb.
Software
The most common web or HTTP server programs are:
- Apache HTTP Server from the Apache Software Foundation.
- Internet Information Services (IIS) from Microsoft.
- Sun ONE from Sun Microsystems, which was formerly Netscape's iPlanet, née Enterprise.
- Zeus Web Server from Zeus Technology (http://www.zeus.com/).
Apache is by far the most common software, with over 69% market share according to the June 2005 Netcraft Web Server Survey (http://news.netcraft.com/archives/web_server_survey.html).
See Category:Web server software for a comprehensive list of HTTP server programs.
See also
External link
- RFC 2616—The Request for Comments document that defines the HTTP 1.1 protocol.da:Webserver
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