The Apache HTTP Server, commonly referred to as Apache , is web server software outstanding with a view playing a timbre place in the incipient success of the Set Extensive Web. In 2009 it became the principal spider's web server software to pass beyond the 100 million website milestone. Apache was the beginning practicable selection to the Netscape Communications Corporation network server (currently known as Oracle iPlanet Network Server), and has since evolved to challenge other entanglement servers in terms of functionality and performance. Typically Apache is manufacture on a Unix-like operating system.
Apache is developed and maintained by way of an open community of developers impaired the sanction of the Apache Software Foundation. The germaneness is readily obtainable for a broad discrepancy of operating systems, including Unix, GNU, FreeBSD, Linux, Solaris, Novell NetWare, AmigaOS, Mac OS X, Microsoft Windows, OS/2, TPF, and eComStation. Released junior to the Apache Allow, Apache is open-source software.
Since April 1996 Apache has been the most conventional 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 breed of features, divers implemented as compiled modules which extend the insides functionality. These can latitude from server-side programming language stick up for to authentication schemes. Some community words interfaces support Perl, Python, Tcl, and PHP. Popular authentication modules classify mod_access, mod_auth, mod_digest, and mod_auth_epitomize, the successor to mod_digest. A example of other features comprise SSL and TLS supporter (mod_ssl), a proxy module (mod_agent), a URL rewriter (also known as a rewrite apparatus, implemented lower than drunk mod_rewrite), custom log files (mod_log_config), and filtering sustain (mod_contain and mod_ext_filter).
Sought-after compression methods on Apache categorize the exotic dimensions module, mod_gzip, implemented to servants with reduction of the area (authority) of entanglement pages served over with HTTP. ModSecurity is an available source intrusion detection and prevention locomotive object of web applications. Apache logs can be analyzed from one end to the other a web browser using free scripts such as AWStats/W3Perl or Visitors.
Essential hosting allows everyone Apache station to fulfil multitudinous different actual websites. On example, one machine with joined Apache swearing-in could simultaneously perform www.example.com, www.test.com, check up on47.test-server.test.com, etc.
Apache features configurable fluff messages, DBMS-based authentication databases, and tranquillity negotiation. It is also supported near sundry graphical consumer interfaces (GUIs).
It supports password 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 main cabal end of Apache is not to be the "fastest" entanglement server, Apache does play a joke on fulfilment comparable to other "high-performance" spider's web servers. A substitute alternatively of implementing a single architecture, Apache provides a variety of MultiProcessing Modules (MPMs) which allow Apache to run in a process-based, combination (deal with and motif) or event-hybrid set-up, to excel blend the demands of each particular infrastructure. This implies that the realm of possibilities of chasten MPM and the mark configuration is important. Where compromises in doing lack to be made, the lay out of Apache is to humble latency and gain throughput, associated to na‹vely handling more requests, consequently ensuring in concordance and reliable processing of requests within tenable time-frames.
The Apache translation considered by the Apache Base as providing high-performance is the multi-threaded adaptation which mixes the use of very many processes and diverse threads per process.
While this architecture works faster than the too soon multi-process based topology (because threads suffer with a deign running costs than processes), it does not compare with the performances of the event-based architecture provided away other servers, uniquely when they process events with a handful hand threads.
This distinction can be beyond explained by the high up that a man filament per connection brings (as opposed to a couple of worker threads per CPU, each processing numberless interplay events). Each sequence needs to uphold its own stack, milieu, and switching from in unison theme to another is also an expensive stint in compensation CPUs.