The Httpd Web Server, commonly referred to as Apache , is web server software matchless with a view playing a key duty in the commencing growth of the Set Wide Web. In 2009 it became the principal web server software to surpass the 100 million website milestone. Apache was the beginning practicable possibility to the Netscape Communications Corporation network server (currently known as Seer iPlanet Web Server), and has since evolved to compete with other snare servers in terms of functionality and performance. Typically Apache is hop to it on a Unix-like operating system.
Apache is developed and maintained during an unspoken for community of developers impaired the approval of the Apache Software Foundation. The application is readily obtainable on a wide multiplicity of operating systems, including Unix, GNU, FreeBSD, Linux, Solaris, Novell NetWare, AmigaOS, Mac OS X, Microsoft Windows, OS/2, TPF, and eComStation. Released supervised the Apache License, Apache is open-source software.
Since April 1996 Apache has been the most popular HTTP server software in use. As of May 2011 Apache was estimated to be accurate 63% of all websites and 66% of the million busiest.
Features

Apache supports a mixture of features, divers implemented as compiled modules which augment the insides functionality. These can choice from server-side programming language authenticate to authentication schemes. Some inferior words interfaces support Perl, Python, Tcl, and PHP. Popular authentication modules include mod_access, mod_auth, mod_pr‚cis, and mod_auth_r‚sum‚, the successor to mod_digest. A example of other features embrace SSL and TLS stick (mod_ssl), a factor module (mod_representative), a URL rewriter (also known as a rewrite appliance, implemented supervised mod_rewrite), to order log files (mod_log_config), and filtering affirm (mod_contain and mod_ext_cheesecloth).
In demand compression methods on Apache categorize the superficial height module, mod_gzip, implemented to ease with reduction of the area (authority) of cobweb pages served to HTTP. ModSecurity is an uncommitted source intrusion detection and interception machine for cobweb applications. Apache logs can be analyzed in the course a web browser using sprung scripts such as AWStats/W3Perl or Visitors.
Virtual hosting allows everyone Apache installation to help innumerable divers verifiable websites. Through despite pattern, joined mechanism with harmonious Apache swearing-in could simultaneously serve www.example.com, www.test.com, evaluate47.test-server.test.com, etc.
Apache features configurable fluff messages, DBMS-based authentication databases, and constituents negotiation. It is also supported not later than disparate graphical consumer interfaces (GUIs).
It supports watchword authentication and digital certificate authentication. Apache has a built in search locomotive and an HTML authorizing dupe and supports FTP.

Performance


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Although the primary cabal aspiration of Apache is not to be the "fastest" trap server, Apache does entertain dispatch comparable to other "high-performance" spider's web servers. Instead of implementing a only architecture, Apache provides a choice of MultiProcessing Modules (MPMs) which concede Apache to skip out in a process-based, hybrid (deal with and filament) or event-hybrid look, to think twice blend the demands of each thorough infrastructure. This implies that the choice of correct MPM and the mark configuration is important. Where compromises in playing dire to be made, the lay out of Apache is to slash latency and advance throughput, appurtenant to to simply handling more requests, consequently ensuring predictable and secure processing of requests within reasonable time-frames.
The Apache version considered past the Apache Endowment as providing high-performance is the multi-threaded translation which mixes the use of several processes and various threads per process.
While this architecture works faster than the erstwhile multi-process based topology (because threads set up a lower running costs than processes), it does not accord the performances of the event-based architecture provided via other servers, unusually when they prepare events with respective hand threads.
This dissimilarity can be without even trying explained by means of the high up that undivided plot per interrelationship brings (as opposed to a four of tradesman threads per CPU, each processing profuse drag relatives events). Each squeeze through needs to keep going its own stack, milieu, and switching from inseparable plot to another is also an high-priced task in compensation CPUs.