The Httpd Web Server, commonly referred to as Apache , is web server software outstanding for playing a pivotal place in the initial success of the Set Big Web. In 2009 it became the principal web server software to pass beyond the 100 million website milestone. Apache was the beginning rapport possibility to the Netscape Communications Corporation network server (currently known as Message iPlanet Entanglement Server), and has since evolved to challenge other trap servers in terms of functionality and performance. Typically Apache is hop to it on a Unix-like operating system.
Apache is developed and maintained not later than an unspoken for community of developers underneath the protection of the Apache Software Foundation. The utilization is ready for a broad variety of operating systems, including Unix, GNU, FreeBSD, Linux, Solaris, Novell NetWare, AmigaOS, Mac OS X, Microsoft Windows, OS/2, TPF, and eComStation. Released junior to the Apache Accredit, 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 variety of features, divers implemented as compiled modules which on the insides functionality. These can class from server-side programming lingo support to authentication schemes. Some inferior jargon interfaces guy Perl, Python, Tcl, and PHP. Favoured authentication modules classify 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 support (mod_ssl), a proxy module (mod_agent), a URL rewriter (also known as a rewrite engine, implemented lower than drunk mod_rewrite), wont log files (mod_log_config), and filtering affirm (mod_register and mod_ext_filter).
Stock compression methods on Apache allow for the exotic augmentation module, mod_gzip, implemented to improve with reduction of the area (strain) of entanglement pages served over with HTTP. ModSecurity is an available fountain-head intrusion detection and interception machine exchange for web applications. Apache logs can be analyzed in the course a snare browser using sprung scripts such as AWStats/W3Perl or Visitors.
Virtual hosting allows one Apache installation to fulfil multitudinous diverse existent websites. On model, joined gizmo with harmonious Apache ordination could simultaneously serve www.example.com, www.test.com, evaluate47.test-server.test.com, etc.
Apache features configurable error messages, DBMS-based authentication databases, and tranquillity negotiation. It is also supported by sundry graphical operator interfaces (GUIs).
It supports password authentication and digital certificate authentication. Apache has a built in search machine and an HTML authorizing gimmick and supports FTP.

Performance


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Although the sheer design goal of Apache is not to be the "fastest" trap server, Apache does play a joke on dispatch comparable to other "high-performance" spider's web servers. As contrasted with of implementing a individual architecture, Apache provides a breed of MultiProcessing Modules (MPMs) which concede Apache to hump it in a process-based, composite (modify and piece of yarn) or event-hybrid look, to better meet the demands of each thorough infrastructure. This implies that the select of correct MPM and the mark configuration is important. Where compromises in dispatch dire to be made, the design of Apache is to belittle latency and increase throughput, appurtenant to to simply handling more requests, thus ensuring accordant and honourable processing of requests within tenable time-frames.
The Apache version considered past the Apache Foundation as providing high-performance is the multi-threaded version which mixes the put to use of several processes and several threads per process.
While this architecture works faster than the previous multi-process based topology (because threads have a deign upper basic than processes), it does not compare with the performances of the event-based architecture provided sooner than other servers, especially when they change events with a variety of worker threads.
This difference can be without even trying explained by the overhead that one thread per relevance brings (as opposed to a four of worker threads per CPU, each processing diverse interplay events). Each thread needs to maintain its own clamp, habitat, and switching from inseparable theme to another is also an high-priced censure after CPUs.