The Httpd Web Server, commonly referred to as Apache , is spider's web server software outstanding with a view playing a level duty in the commencing growth of the World Big Web. In 2009 it became the beginning cobweb server software to outshine the 100 million website milestone. Apache was the beginning feasible possibility to the Netscape Communications Corporation web server (currently known as Oracle iPlanet Entanglement Server), and has since evolved to rival other trap 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 unspoken for community of developers impaired the protection 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 Commission, 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 mixture of features, varied implemented as compiled modules which augment the pit functionality. These can choice from server-side programming phrasing support to authentication schemes. Some inferior lingua franca interfaces support Perl, Python, Tcl, and PHP. In demand authentication modules include mod_access, mod_auth, mod_pr‚cis, and mod_auth_synopsis, the successor to mod_digest. A sample of other features classify SSL and TLS stick (mod_ssl), a factor module (mod_agent), a URL rewriter (also known as a rewrite apparatus, implemented supervised mod_rewrite), to order log files (mod_log_config), and filtering sustain (mod_contain and mod_ext_screen).
In demand compression methods on Apache take in the exotic augmentation module, mod_gzip, implemented to servants with reduction of the appraise (authority) of cobweb pages served during the course of HTTP. ModSecurity is an uncommitted rise intrusion detection and prevention apparatus in the direction of entanglement applications. Apache logs can be analyzed from one end to the other a web browser using relieved of scripts such as AWStats/W3Perl or Visitors.
Effective hosting allows one Apache investiture to fulfil many different physical websites. For pattern, one gizmo with harmonious Apache consecration could simultaneously favourable to www.example.com, www.test.com, evaluate47.test-server.test.com, etc.
Apache features configurable boob messages, DBMS-based authentication databases, and capacity negotiation. It is also supported next to several graphical drug interfaces (GUIs).
It supports shibboleth authentication and digital certificate authentication. Apache has a built in search machine and an HTML authorizing tool and supports FTP.

Performance


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Although the sheer layout goal of Apache is not to be the "fastest" entanglement server, Apache does take fulfilment comparable to other "high-performance" spider's web servers. In lieu of of implementing a only architecture, Apache provides a variety of MultiProcessing Modules (MPMs) which deduct Apache to run in a process-based, hybrid (deal with and thread) or event-hybrid way, to better match the demands of each particular infrastructure. This implies that the preference of suitable MPM and the nullify configuration is important. Where compromises in doing dire to be made, the stratagem of Apache is to humble latency and advance throughput, appurtenant to to na‹vely handling more requests, thus ensuring accordant and trusted processing of requests within logical time-frames.
The Apache version considered by means of the Apache Foundation as providing high-performance is the multi-threaded adaptation which mixes the manipulate of a handful processes and several threads per process.
While this architecture works faster than the erstwhile multi-process based topology (because threads have a lower upper basic than processes), it does not copy the performances of the event-based architecture provided by other servers, uncommonly when they prepare events with respective worker threads.
This dissimilarity can be smoothly explained by the overhead that identical thread per interrelationship brings (as opposed to a yoke of tradesman threads per CPU, each processing numberless correlation events). Each squeeze through needs to contend its own stack, milieu, and switching from one thread to another is also an expensive stint for CPUs.