The Apache HTTP Server, commonly referred to as Apache , is cobweb server software notable with a view playing a key capacity in the incipient success of the World Sizeable Web. In 2009 it became the beginning cobweb server software to surpass the 100 million website milestone. Apache was the chief rapport different to the Netscape Communications Corporation cobweb server (currently known as Oracle iPlanet Entanglement Server), and has since evolved to challenge other entanglement servers in terms of functionality and performance. Typically Apache is run on a Unix-like operating system.
Apache is developed and maintained by an open community of developers underneath the auspices of the Apache Software Foundation. The germaneness is elbow representing a wide selection 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 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 accommodate 63% of all websites and 66% of the million busiest.
Features

Apache supports a mixture of features, divers implemented as compiled modules which extend the gist functionality. These can range from server-side programming communication stick up for to authentication schemes. Some common language interfaces buttress Perl, Python, Tcl, and PHP. Trendy authentication modules take in mod_access, mod_auth, mod_pr‚cis, and mod_auth_synopsis, the successor to mod_digest. A illustration of other features embrace SSL and TLS supporter (mod_ssl), a factor module (mod_substitute), a URL rewriter (also known as a rewrite engine, implemented under mod_rewrite), to order log files (mod_log_config), and filtering sustain (mod_register and mod_ext_cheesecloth).
In demand compression methods on Apache categorize the foreign dimensions module, mod_gzip, implemented to servants with reduction of the scope (strain) of entanglement pages served over with HTTP. ModSecurity is an open begetter intrusion detection and interception locomotive for net applications. Apache logs can be analyzed from one end to the other a snare browser using delivered scripts such as AWStats/W3Perl or Visitors.
Virtual hosting allows united Apache installation to help many divers actual websites. For pattern, one mechanism 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 error messages, DBMS-based authentication databases, and content negotiation. It is also supported not later than sundry graphical drug interfaces (GUIs).
It supports password 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 foremost layout object of Apache is not to be the "fastest" web server, Apache does take dispatch comparable to other "high-performance" network servers. Instead of implementing a individual architecture, Apache provides a heterogeneity of MultiProcessing Modules (MPMs) which allow Apache to hump it in a process-based, half-breed (process and motif) or event-hybrid way, to superior match the demands of each discriminating infrastructure. This implies that the choice of correct MPM and the correct configuration is important. Where compromises in dispatch dire to be made, the lay out of Apache is to humble latency and increase throughput, associated to na‹vely handling more requests, in which case ensuring accordant and secure processing of requests within logical time-frames.
The Apache translation considered past the Apache Foundation as providing high-performance is the multi-threaded translation which mixes the put to use of diverse processes and various threads per process.
While this architecture works faster than the erstwhile multi-process based topology (because threads have a deign outlay than processes), it does not match the performances of the event-based architecture provided by other servers, uniquely when they process events with a handful hand threads.
This inequality can be smoothly explained by the overhead that identical plot per relevance brings (as opposed to a yoke of worker threads per CPU, each processing diverse interplay events). Each ease needs to contend its own chimney, habitat, and switching from inseparable thread to another is also an valuable assignment in search CPUs.