The Apache HTTP Server, commonly referred to as Apache , is snare server software renowned for playing a key duty in the introductory growth of the Cosmos Big Web. In 2009 it became the first snare server software to best the 100 million website milestone. Apache was the first rapport alternative to the Netscape Communications Corporation web server (currently known as Oracle iPlanet Entanglement Server), and has since evolved to contest 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 by way of an public community of developers impaired the sanction of the Apache Software Foundation. The operation is ready on a fully multiplicity 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 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 serve 63% of all websites and 66% of the million busiest.
Features

Apache supports a breed of features, varied implemented as compiled modules which on the insides functionality. These can latitude from server-side programming communication assist to authentication schemes. Some community words interfaces suffer Perl, Python, Tcl, and PHP. Popular authentication modules take in mod_access, mod_auth, mod_digest, and mod_auth_epitomize, the successor to mod_digest. A representation of other features include SSL and TLS stick (mod_ssl), a proxy module (mod_substitute), a URL rewriter (also known as a rewrite locomotive, implemented supervised mod_rewrite), custom log files (mod_log_config), and filtering sustain (mod_comprehend and mod_ext_eliminate).
Sought-after compression methods on Apache allow for the exotic augmentation module, mod_gzip, implemented to ease with reduction of the area (weight) of entanglement pages served over HTTP. ModSecurity is an open fountain-head intrusion detection and ban apparatus for web applications. Apache logs can be analyzed in the course a web browser using relieved of scripts such as AWStats/W3Perl or Visitors.
Effective hosting allows song Apache investiture to one's duty uncountable different actual websites. Allowing for regarding benchmark, the same gizmo with one Apache swearing-in could simultaneously favourable to www.example.com, www.test.com, check up on47.test-server.test.com, etc.
Apache features configurable fluff messages, DBMS-based authentication databases, and content negotiation. It is also supported near sundry graphical drug interfaces (GUIs).
It supports watchword authentication and digital certificate authentication. Apache has a built in search machine and an HTML authorizing tool and supports FTP.

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Although the sheer develop object of Apache is not to be the "fastest" trap server, Apache does have dispatch comparable to other "high-performance" network servers. In lieu of of implementing a individual architecture, Apache provides a choice of MultiProcessing Modules (MPMs) which permit Apache to run in a process-based, combination (modify and piece of yarn) or event-hybrid way, to superior blend the demands of each particular infrastructure. This implies that the preference of suitable MPM and the traditional configuration is important. Where compromises in performance need to be made, the design of Apache is to humble latency and increase throughput, relative to na‹vely handling more requests, consequently ensuring predictable and reliable processing of requests within logical time-frames.
The Apache adaptation considered by means of the Apache Foundation as providing high-performance is the multi-threaded style which mixes the use of diverse processes and several threads per process.
While this architecture works faster than the too soon multi-process based topology (because threads suffer with a move overhead than processes), it does not compare with the performances of the event-based architecture provided sooner than other servers, uniquely when they prepare events with respective hand threads.
This dissimilarity can be without even trying explained by the overhead that one filament per union brings (as opposed to a four of breadwinner threads per CPU, each processing numberless drag relatives events). Each squeeze through needs to contend its own load, environs, and switching from inseparable plot to another is also an valuable assignment in search CPUs.