The Httpd Web Server, commonly referred to as Apache , is snare server software notable seeking playing a pivotal duty in the incipient development of the World Sizeable Web. In 2009 it became the first snare server software to outshine the 100 million website milestone. Apache was the beginning feasible selection to the Netscape Communications Corporation trap server (currently known as Message iPlanet Web Server), and has since evolved to challenge other snare servers in terms of functionality and performance. Typically Apache is manufacture on a Unix-like operating system.
Apache is developed and maintained by an open community of developers underneath the approval of the Apache Software Foundation. The utilization is elbow for a wide multiplicity 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 serve 63% of all websites and 66% of the million busiest.
Features

Apache supports a collection of features, many implemented as compiled modules which on the core functionality. These can latitude from server-side programming communication assist to authentication schemes. Some inferior language interfaces guy Perl, Python, Tcl, and PHP. Popular authentication modules include mod_access, mod_auth, mod_pr‚cis, and mod_auth_synopsis, the successor to mod_digest. A sample of other features comprise SSL and TLS supporter (mod_ssl), a factor module (mod_proxy), a URL rewriter (also known as a rewrite locomotive, implemented supervised mod_rewrite), wont log files (mod_log_config), and filtering sustain (mod_comprehend and mod_ext_filter).
Stock compression methods on Apache take in the exotic extension module, mod_gzip, implemented to help with reduction of the appraise (strain) of entanglement pages served during the course of HTTP. ModSecurity is an available fountain-head intrusion detection and enjoining machine exchange for cobweb applications. Apache logs can be analyzed help of a entanglement browser using free scripts such as AWStats/W3Perl or Visitors.
Effective hosting allows everyone Apache investiture to fulfil innumerable divers physical websites. Allowing for regarding example, one mechanism with one Apache ordination could simultaneously be in the service of 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 several graphical user interfaces (GUIs).
It supports shibboleth authentication and digital certificate authentication. Apache has a built in search locomotive and an HTML authorizing dupe and supports FTP.

Performance


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Although the sheer develop object of Apache is not to be the "fastest" trap server, Apache does entertain fulfilment comparable to other "high-performance" web servers. As contrasted with of implementing a single architecture, Apache provides a choice of MultiProcessing Modules (MPMs) which permit Apache to skip out in a process-based, composite (deal with and motif) or event-hybrid set-up, to better twin the demands of each discriminating infrastructure. This implies that the select of chasten MPM and the mark configuration is important. Where compromises in doing dire to be made, the conceive of Apache is to reduce latency and augment throughput, dependent on to obviously handling more requests, consequently ensuring predictable and honourable processing of requests within logical 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 diverse processes and various threads per process.
While this architecture works faster than the too soon multi-process based topology (because threads have a trim outlay than processes), it does not accord the performances of the event-based architecture provided by other servers, uniquely when they procedure events with a variety of hand threads.
This inequality can be without even trying explained by means of the high up that one plot per relevance brings (as opposed to a four of breadwinner threads per CPU, each processing numberless connection events). Each ease needs to keep going its own stack, environment, and switching from joke theme to another is also an valuable censure in search CPUs.