A web server is computer software and underlying hardware that accepts requests via HTTP or its secure variant HTTPS. A user agent, commonly a web browser or web crawler, initiates communication by making a request for a web page or other resource using HTTP, and the server responds with the content of that resource or an error message. A web server can also accept and store resources sent from the user agent if configured to do so.
In computer networking, a proxy server is a server application that acts as an intermediary between a client requesting a resource and the server providing that resource. It improves privacy, security, and performance in the process.
Privoxy is a free non-caching web proxy with filtering capabilities for enhancing privacy, manipulating cookies and modifying web page data and HTTP headers before the page is rendered by the browser. Privoxy is a "privacy enhancing proxy", filtering web pages and removing advertisements. Privoxy can be customized by users, for both stand-alone systems and multi-user networks. Privoxy can be chained to other proxies and is frequently used in combination with Squid among others and can be used to bypass Internet censorship.
Squid is a caching and forwarding HTTP web proxy. It has a wide variety of uses, including speeding up a web server by caching repeated requests, caching World Wide Web (WWW), Domain Name System (DNS), and other network lookups for a group of people sharing network resources, and aiding security by filtering traffic. Although used for mainly HTTP and File Transfer Protocol (FTP), Squid includes limited support for several other protocols including Internet Gopher, Secure Sockets Layer (SSL), Transport Layer Security (TLS), and Hypertext Transfer Protocol Secure (HTTPS). Squid does not support the SOCKS protocol, unlike Privoxy, with which Squid can be used in order to provide SOCKS support.
A Web cache is a system for optimizing the World Wide Web. It is implemented both client-side and server-side. The caching of multimedia and other files can result in less overall delay when browsing the Web.
lighttpd is an open-source web server optimized for speed-critical environments while remaining standards-compliant, secure and flexible. It was originally written by Jan Kneschke as a proof-of-concept of the c10k problem – how to handle 10,000 connections in parallel on one server, but has gained worldwide popularity. Its name is a portmanteau of "light" and "httpd".
In computer networks, a reverse proxy or surrogate server is a proxy server that appears to any client to be an ordinary web server, but in reality merely acts as an intermediary that forwards the client's requests to one or more ordinary web servers. Reverse proxies help increase scalability, performance, resilience, and security, but they also carry a number of risks.
A web accelerator is a proxy server that reduces website access time. They can be a self-contained hardware appliance or installable software.
Google Web Accelerator was a web accelerator produced by Google. It used client software installed on the user's computer, as well as data caching on Google's servers, to speed up page load times by means of data compression, prefetching of content, and sharing cached data between users. The beta, released on May 4, 2005, works with Mozilla Firefox 1.0+ and Internet Explorer 5.5+ on Windows 2000 SP3+, Windows XP, Windows Server 2003, Windows Vista and Windows 7 machines. It was discontinued in October 2008.
Sun Microsystems' UltraSPARC T1 microprocessor, known until its 14 November 2005 announcement by its development codename "Niagara", is a multithreading, multicore CPU. Designed to lower the energy consumption of server computers, the CPU typically uses 72 W of power at 1.4 GHz.
A proxy auto-config (PAC) file defines how web browsers and other user agents can automatically choose the appropriate proxy server for fetching a given URL.
Pound is a lightweight open source reverse proxy program and application firewall suitable to be used as a web server load balancing solution. Originally developed by an IT security company, it has a strong emphasis on security. The original intent on developing Pound was to allow distributing the load among several Zope servers running on top of ZEO. However, Pound is not limited to Zope-based installations. Using regular expression matching on the requested URLs, Pound can pass different kinds of requests to different backend server groups. A few more of its most important features:
A PHP accelerator is a PHP extension designed to improve the performance of software applications written in the PHP programming language.
Varnish is a reverse caching proxy used as HTTP accelerator for content-heavy dynamic web sites as well as APIs. In contrast to other web accelerators, such as Squid, which began life as a client-side cache, or Apache and nginx, which are primarily origin servers, Varnish was designed as an HTTP accelerator. Varnish is focused exclusively on HTTP, unlike other proxy servers that often support FTP, SMTP, and other network protocols.
Nginx is a web server that can also be used as a reverse proxy, load balancer, mail proxy and HTTP cache. The software was created by Russian developer Igor Sysoev and publicly released in 2004. Nginx is free and open-source software, released under the terms of the 2-clause BSD license. A large fraction of web servers use Nginx, often as a load balancer.
Resin is a web server and Java application server developed by Caucho Technology. There are currently only two versions available: Resin (GPL), which is free for production use, and Resin Pro, designed for enterprise and production environments with a licensing fee. Resin supports the Java EE standard and features a mod_php/PHP-like engine known as Quercus.
Polipo is a discontinued lightweight caching and forwarding web proxy server. It has a wide variety of uses, from aiding security by filtering traffic; to caching web, DNS and other computer network lookups for a group of people sharing network resources; to speeding up a web server by caching repeated requests. It can be configured to use on-disk cache and serve cached content when offline and perform various forms of content filtering.
Cherokee is an open-source cross-platform web server that runs on Linux, BSD variants, Solaris, OS X, and Windows. It is a lightweight, high-performance web server/reverse proxy licensed under the GNU General Public License. Its goal is to be fast and fully functional yet still light. Major features of Cherokee include a graphical administration interface named cherokee-admin, and a modular light-weight design.
