The Apache HTTP Server Project is a collaborative software development effort aimed at creating a robust, commercial-grade, featureful, and freely-available source code implementation of an HTTP (Web) server. The project is jointly managed by a group of volunteers located around the world, using the Internet and the Web to communicate, plan, and develop the server and its related documentation. This project is part of the Apache Software Foundation. In addition, hundreds of users have contributed ideas, code, and documentation to the project. This file is intended to briefly describe the history of the Apache HTTP Server and recognize the many contributors.

The Number One HTTP Server On The Internet

The Apache HTTP Server Project is an effort to develop and maintain an open-source HTTP server for modern operating systems including UNIX and Windows. The goal of this project is to provide a secure, efficient and extensible server that provides HTTP services in sync with the current HTTP standards.

Features

A more detailed list of features is provided below:

• Loadable Dynamic Modules
• Multiple Request Processing modes (MPMs) including Event-based/Async, Threaded and Prefork.
• Highly scalable (easily handles more than 10,000 simultaneous connections)
• Handling of static files, index files, auto-indexing and content negotiation
• .htaccess per-directory configuration support^[25]
• Reverse proxy with caching^[26]
  • Load balancing with in-band health checks
  • Multiple load balancing mechanisms
  • Fault tolerance and Failover with automatic recovery
  • WebSocket, FastCGI, SCGI, AJP and uWSGI support with caching
  • Dynamic configuration
• TLS/SSL with SNI and OCSP stapling support, via OpenSSL or wolfSSL.
• Name- and IP address-based virtual servers
• IPv6-compatible
• HTTP/2 support
• Fine-grained authentication and authorization access control
• gzip compression and decompression
• URL rewriting
• Headers and content rewriting
• Custom logging with rotation
• Concurrent connection limiting
• Request processing rate limiting
• Bandwidth throttling
• Server Side Includes
• IP address-based geolocation
• User and Session tracking
• WebDAV
• Embedded Perl, PHP and Lua scripting
• CGI support
• public_html per-user web-pages
• Generic expression parser
• Real-time status views
• FTP support (by a separate module)

Performance

Instead of implementing a single architecture, Apache provides a variety of MultiProcessing Modules (MPMs), which allow it to run in either a process-based mode, a hybrid (process and thread) mode, or an event-hybrid mode, in order to better match the demands of each particular infrastructure. Choice of MPM and configuration is therefore important. Where compromises in performance must be made, Apache is designed to reduce latency and increase throughput relative to simply handling more requests, thus ensuring consistent and reliable processing of requests within reasonable time-frames.

For delivering static pages, Apache 2.2 series was considered significantly slower than nginx and varnish.^[ To address this issue, the Apache developers created the Event MPM, which mixes the use of several processes and several threads per process in an asynchronous event-based loop. This architecture as implemented in the Apache 2.4 series performs at least as well as event-based web servers, according to Jim Jagielski and other independent sources. However, some independent but significantly outdated benchmarks show that it is still half as fast as nginx.

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