The Apache HTTP Server, commonly referred to as Apache , is snare server software renowned with a view playing a key role in the introductory broadening of the Society Big Web. In 2009 it became the ahead cobweb server software to pass beyond the 100 million website milestone. Apache was the beginning rapport selection to the Netscape Communications Corporation cobweb server (currently known as Message iPlanet Network Server), and has since evolved to compete with other web servers in terms of functionality and performance. Typically Apache is manufacture on a Unix-like operating system.
Apache is developed and maintained during an open community of developers underneath the approval of the Apache Software Foundation. The operation is available instead of a broad multiplicity of operating systems, including Unix, GNU, FreeBSD, Linux, Solaris, Novell NetWare, AmigaOS, Mac OS X, Microsoft Windows, OS/2, TPF, and eComStation. Released under the Apache Accredit, Apache is open-source software.
Since April 1996 Apache has been the most fashionable HTTP server software in use. As of May 2011 Apache was estimated to serve 63% of all websites and 66% of the million busiest.
Features

Apache supports a mixture of features, many implemented as compiled modules which on the gist functionality. These can class from server-side programming language stick up for to authentication schemes. Some inferior language interfaces buttress Perl, Python, Tcl, and PHP. In demand authentication modules classify mod_access, mod_auth, mod_grasp, and mod_auth_epitomize, the successor to mod_digest. A illustration of other features embrace SSL and TLS stick (mod_ssl), a surrogate module (mod_agent), a URL rewriter (also known as a rewrite apparatus, implemented lower than drunk mod_rewrite), wont log files (mod_log_config), and filtering sustain (mod_comprehend and mod_ext_filter).
Popular compression methods on Apache categorize the superficial extension module, mod_gzip, implemented to improve with reduction of the appraise (strain) of snare pages served over HTTP. ModSecurity is an uncover fountain-head intrusion detection and enjoining machine for web applications. Apache logs can be analyzed from one end to the other a entanglement browser using relieved of scripts such as AWStats/W3Perl or Visitors.
Effective hosting allows everyone Apache consecration to serve innumerable unalike actual websites. For example, joined gizmo with harmonious Apache swearing-in could simultaneously be in the service of www.example.com, www.test.com, evaluate47.test-server.test.com, etc.
Apache features configurable boob messages, DBMS-based authentication databases, and constituents negotiation. It is also supported next to sundry graphical user interfaces (GUIs).
It supports shibboleth authentication and digital certificate authentication. Apache has a built in search machine and an HTML authorizing gimmick and supports FTP.

Performance


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Although the sheer design goal of Apache is not to be the "fastest" spider's web server, Apache does take dispatch comparable to other "high-performance" web servers. A substitute alternatively of implementing a only architecture, Apache provides a choice of MultiProcessing Modules (MPMs) which deduct Apache to skip out in a process-based, combination (deal with and filament) or event-hybrid way, to excel blend the demands of each discriminating infrastructure. This implies that the select of suitable MPM and the traditional configuration is important. Where compromises in doing desperate straits to be made, the conceive of Apache is to slash latency and increase throughput, associated to austerely handling more requests, that reason ensuring in concordance and honourable processing of requests within tenable time-frames.
The Apache adaptation considered by means of the Apache Foundation as providing high-performance is the multi-threaded style which mixes the manipulate of diverse processes and several threads per process.
While this architecture works faster than the erstwhile multi-process based topology (because threads prepare a deign outlay than processes), it does not match the performances of the event-based architecture provided via other servers, uniquely when they process events with respective wage-earner threads.
This inequality can be easily explained by the high up that identical filament per relevance brings (as opposed to a twosome of worker threads per CPU, each processing profuse interplay events). Each ease needs to contend its own clamp, habitat, and switching from inseparable thread to another is also an high-priced stint after CPUs.