The Apache HTTP Server, commonly referred to as Apache , is web server software renowned for the purpose playing a key place in the initial success of the World Big Web. In 2009 it became the ahead spider's web server software to surpass the 100 million website milestone. Apache was the beginning practicable different to the Netscape Communications Corporation web server (currently known as Oracle iPlanet Snare 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 an bare community of developers impaired the protection of the Apache Software Foundation. The application is available on a broad selection of operating systems, including Unix, GNU, FreeBSD, Linux, Solaris, Novell NetWare, AmigaOS, Mac OS X, Microsoft Windows, OS/2, TPF, and eComStation. Released supervised the Apache Commission, Apache is open-source software.
Since April 1996 Apache has been the most fashionable HTTP server software in use. As of May 2011 Apache was estimated to minister to 63% of all websites and 66% of the million busiest.
Features

Apache supports a breed of features, many implemented as compiled modules which proffer the pit functionality. These can class from server-side programming lingo authenticate to authentication schemes. Some common words interfaces suffer Perl, Python, Tcl, and PHP. Trendy authentication modules take in mod_access, mod_auth, mod_digest, and mod_auth_digest, the successor to mod_digest. A sample of other features comprise SSL and TLS stick (mod_ssl), a representative module (mod_representative), a URL rewriter (also known as a rewrite locomotive, implemented under mod_rewrite), to order log files (mod_log_config), and filtering sustain (mod_contain and mod_ext_cheesecloth).
Sought-after compression methods on Apache include the foreign dimensions module, mod_gzip, implemented to improve with reduction of the size (authority) of cobweb pages served over HTTP. ModSecurity is an open rise intrusion detection and interception engine object of cobweb applications. Apache logs can be analyzed through a entanglement browser using sprung scripts such as AWStats/W3Perl or Visitors.
Virtual hosting allows song Apache installation to serve uncountable different existent websites. Allowing for regarding pattern, the same mechanism with united Apache ordination could simultaneously be in the service of www.example.com, www.test.com, examine47.test-server.test.com, etc.
Apache features configurable slip-up messages, DBMS-based authentication databases, and content negotiation. It is also supported next to respective graphical operator interfaces (GUIs).
It supports watchword authentication and digital certificate authentication. Apache has a built in search machine and an HTML authorizing dupe and supports FTP.

Engagement


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Although the main layout aspiration of Apache is not to be the "fastest" entanglement server, Apache does take dispatch comparable to other "high-performance" web servers. In lieu of of implementing a single architecture, Apache provides a breed of MultiProcessing Modules (MPMs) which deduct Apache to skip out in a process-based, half-breed (modify and motif) or event-hybrid way, to superior meet the demands of each particular infrastructure. This implies that the select of chasten MPM and the traditional configuration is important. Where compromises in dispatch need to be made, the design of Apache is to slash latency and augment throughput, relative to austerely handling more requests, thus ensuring predictable and trusted processing of requests within tenable time-frames.
The Apache reading considered by the Apache Base as providing high-performance is the multi-threaded adaptation which mixes the utilize consume of several processes and several threads per process.
While this architecture works faster than the erstwhile multi-process based topology (because threads have a lower running costs than processes), it does not copy the performances of the event-based architecture provided by other servers, especially when they procedure events with a handful hand threads.
This inequality can be smoothly explained beside the aloft that undivided thread per connection brings (as opposed to a four of breadwinner threads per CPU, each processing many interplay events). Each squeeze through needs to keep going its own clamp, milieu, and switching from in unison string to another is also an expensive assignment for CPUs.