The Httpd Web Server, commonly referred to as Apache , is web server software renowned seeking playing a level capacity in the commencing growth of the Society Wide Web. In 2009 it became the principal snare server software to best the 100 million website milestone. Apache was the chief practicable possibility to the Netscape Communications Corporation web server (currently known as Message iPlanet Web Server), and has since evolved to contest other snare servers in terms of functionality and performance. Typically Apache is escape on a Unix-like operating system.
Apache is developed and maintained by an bare community of developers under the auspices of the Apache Software Foundation. The germaneness 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 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 minister to 63% of all websites and 66% of the million busiest.
Features

Apache supports a breed of features, divers implemented as compiled modules which extend the pit functionality. These can choice from server-side programming phrasing support to authentication schemes. Some community lingua franca interfaces suffer Perl, Python, Tcl, and PHP. Favoured authentication modules include mod_access, mod_auth, mod_grasp, and mod_auth_digest, the successor to mod_digest. A example of other features embrace SSL and TLS stick (mod_ssl), a proxy module (mod_agent), a URL rewriter (also known as a rewrite appliance, implemented high mod_rewrite), custom log files (mod_log_config), and filtering support (mod_contain and mod_ext_cheesecloth).
Stock compression methods on Apache categorize the exotic height module, mod_gzip, implemented to help with reduction of the appraise (authority) of entanglement pages served to HTTP. ModSecurity is an uncommitted source intrusion detection and prevention apparatus exchange for entanglement applications. Apache logs can be analyzed through a snare browser using free scripts such as AWStats/W3Perl or Visitors.
Effective hosting allows song Apache station to fulfil uncountable different physical websites. For pattern, the same machine with one Apache installation could simultaneously serve 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 next to respective graphical drug interfaces (GUIs).
It supports watchword authentication and digital certificate authentication. Apache has a built in search engine and an HTML authorizing contraption and supports FTP.

Engagement


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Although the primary design aspiration of Apache is not to be the "fastest" web server, Apache does have performance comparable to other "high-performance" trap servers. In lieu of of implementing a fix architecture, Apache provides a breed of MultiProcessing Modules (MPMs) which permit Apache to skip out in a process-based, combination (function and motif) or event-hybrid look, to superior twin the demands of each separate infrastructure. This implies that the select of chasten MPM and the correct configuration is important. Where compromises in dispatch dire to be made, the lay out of Apache is to belittle latency and increase throughput, associated to austerely handling more requests, that reason ensuring in concordance and secure processing of requests within judicious time-frames.
The Apache adaptation considered by means of the Apache Foundation as providing high-performance is the multi-threaded version which mixes the put to use of several processes and diverse threads per process.
While this architecture works faster than the erstwhile multi-process based topology (because threads set up a deign overhead than processes), it does not copy the performances of the event-based architecture provided via other servers, unusually when they process events with respective worker threads.
This distinction can be beyond explained by means of the overhead that identical plot per relevance brings (as opposed to a twosome of wage-earner threads per CPU, each processing many correlation events). Each squeeze through needs to maintain its own stack, milieu, and switching from joke thread to another is also an valuable stint after CPUs.