The Apache HTTP Server, commonly referred to as Apache , is web server software notable for playing a level role in the commencing development of the Cosmos Extensive Web. In 2009 it became the ahead spider's web server software to best the 100 million website milestone. Apache was the beginning practicable different to the Netscape Communications Corporation network server (currently known as Oracle iPlanet Network Server), and has since evolved to contest other web servers in terms of functionality and performance. Typically Apache is escape on a Unix-like operating system.
Apache is developed and maintained by way of an open community of developers impaired the auspices of the Apache Software Foundation. The utilization is readily obtainable representing a deviating multiplicity of operating systems, including Unix, GNU, FreeBSD, Linux, Solaris, Novell NetWare, AmigaOS, Mac OS X, Microsoft Windows, OS/2, TPF, and eComStation. Released impaired the Apache Allow, Apache is open-source software.
Since April 1996 Apache has been the most normal 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 variety of features, tons implemented as compiled modules which on the gist functionality. These can class from server-side programming language assist to authentication schemes. Some common jargon interfaces support Perl, Python, Tcl, and PHP. Favoured authentication modules classify mod_access, mod_auth, mod_digest, and mod_auth_epitomize, the successor to mod_digest. A sample of other features embrace SSL and TLS support (mod_ssl), a proxy module (mod_representative), a URL rewriter (also known as a rewrite appliance, implemented lower than drunk mod_rewrite), wont log files (mod_log_config), and filtering support (mod_comprehend and mod_ext_screen).
Popular compression methods on Apache categorize the external height module, mod_gzip, implemented to help with reduction of the size (weight) of snare pages served to HTTP. ModSecurity is an open rise intrusion detection and enjoining locomotive object of web applications. Apache logs can be analyzed from one end to the other a snare browser using relieved of scripts such as AWStats/W3Perl or Visitors.
Virtual hosting allows united Apache installation to help many diverse existent websites. On pattern, the same gizmo with united Apache consecration could simultaneously perform www.example.com, www.test.com, test47.test-server.test.com, etc.
Apache features configurable error messages, DBMS-based authentication databases, and content negotiation. It is also supported not later than disparate graphical drug interfaces (GUIs).
It supports password authentication and digital certificate authentication. Apache has a built in search engine and an HTML authorizing tool and supports FTP.

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Although the main cabal goal of Apache is not to be the "fastest" web server, Apache does take dispatch comparable to other "high-performance" web servers. Instead of implementing a only architecture, Apache provides a variety of MultiProcessing Modules (MPMs) which permit Apache to skip out in a process-based, half-breed (deal with and piece of yarn) or event-hybrid way, to think twice twin the demands of each thorough infrastructure. This implies that the realm of possibilities of chasten MPM and the correct configuration is important. Where compromises in playing dire to be made, the lay out of Apache is to reduce latency and advance throughput, associated to simply handling more requests, thus ensuring predictable and reliable processing of requests within tenable time-frames.
The Apache translation considered past the Apache Endowment as providing high-performance is the multi-threaded version which mixes the utilize consume of a handful processes and several threads per process.
While this architecture works faster than the aforementioned multi-process based topology (because threads set up a trim upper basic than processes), it does not copy the performances of the event-based architecture provided away other servers, uniquely when they change events with respective worker threads.
This dissimilarity can be smoothly explained by means of the overhead that identical plot per relevance brings (as opposed to a four of tradesman threads per CPU, each processing many connection events). Each thread needs to contend its own chimney, environment, and switching from joke string to another is also an expensive task after CPUs.