Web accelerator
Encyclopedia
A web accelerator is a proxy server
Proxy server
In computer networks, a proxy server is a server that acts as an intermediary for requests from clients seeking resources from other servers. A client connects to the proxy server, requesting some service, such as a file, connection, web page, or other resource available from a different server...

 that reduces web site access time
Access time
Access time is the time delay or latency between a request to an electronic system, and the access being completed or the requested data returned....

s. They can be a self-contained hardware appliance or installable software.

Web accelerators may be installed on the client (browsing) computer / mobile device, on ISP servers, on the server computer/network, or a combination. Accelerating delivery through compression requires some type of host based server to collect, compress and then deliver content to a client computer.

Techniques

Web accelerators may use several techniques to achieve this reduction:
  • They may cache
    Web cache
    A web cache is a mechanism for the temporary storage of web documents, such as HTML pages and images, to reduce bandwidth usage, server load, and perceived lag...

     recently or frequently accessed documents
    Electronic document
    An electronic document is any electronic media content that are intended to be used in either an electronic form or as printed output....

     so they may be sent to the client
    Client (computing)
    A client is an application or system that accesses a service made available by a server. The server is often on another computer system, in which case the client accesses the service by way of a network....

     with less latency
    Lag
    Lag is a common word meaning to fail to keep up or to fall behind. In real-time applications, the term is used when the application fails to respond in a timely fashion to inputs...

     or at a faster transfer rate than the remote server
    Server (computing)
    In the context of client-server architecture, a server is a computer program running to serve the requests of other programs, the "clients". Thus, the "server" performs some computational task on behalf of "clients"...

     could.
  • They may freshen objects in the cache ensuring that frequently accessed content is readily available for display.
  • They may preemptively resolve hostnames
    Domain name system
    The Domain Name System is a hierarchical distributed naming system for computers, services, or any resource connected to the Internet or a private network. It associates various information with domain names assigned to each of the participating entities...

     present in a document (HTML
    HTML
    HyperText Markup Language is the predominant markup language for web pages. HTML elements are the basic building-blocks of webpages....

     or Javascript
    JavaScript
    JavaScript is a prototype-based scripting language that is dynamic, weakly typed and has first-class functions. It is a multi-paradigm language, supporting object-oriented, imperative, and functional programming styles....

    ) in order to reduce latency.
  • They may prefetch
    Link prefetching
    Link prefetching is a proprietary syntax to give web browsers a hint about documents that it should pre-fetch because the user might visit them in the near future. It is proposed as a draft internet standard by Mozilla...

     documents that are likely to be accessed in the near future.
  • They may compress
    Data compression
    In computer science and information theory, data compression, source coding or bit-rate reduction is the process of encoding information using fewer bits than the original representation would use....

     documents to a smaller size, for example by reducing the quality of images
    Digital image
    A digital image is a numeric representation of a two-dimensional image. Depending on whether or not the image resolution is fixed, it may be of vector or raster type...

     or by sending only what's changed since the document was last requested.
  • They may optimize
    Optimization (computer science)
    In computer science, program optimization or software optimization is the process of modifying a software system to make some aspect of it work more efficiently or use fewer resources...

     the code from certain documents (such as HTML
    HTML
    HyperText Markup Language is the predominant markup language for web pages. HTML elements are the basic building-blocks of webpages....

     or Javascript
    JavaScript
    JavaScript is a prototype-based scripting language that is dynamic, weakly typed and has first-class functions. It is a multi-paradigm language, supporting object-oriented, imperative, and functional programming styles....

    ).
  • They may filter
    Filter (software)
    A filter is a computer program to process a data stream. Some operating systems such as Unix are rich with filter programs. Even Windows has some simple filters built into its command shell, most of which have significant enhancements relative to the similar filter commands that were available in...

     out ads and other undesirable objects so they are not sent to the client at all.
  • They may maintain persistent TCP
    Transmission Control Protocol
    The Transmission Control Protocol is one of the core protocols of the Internet Protocol Suite. TCP is one of the two original components of the suite, complementing the Internet Protocol , and therefore the entire suite is commonly referred to as TCP/IP...

     connections between the client and the proxy server.
  • They may improve the performance via protocol level accelerations, such as TCP acceleration
    TCP Acceleration
    TCP acceleration is the name of a series of techniques for achieving better throughput on an Internet connection than standard TCP achieves, without modifying the end applications...

    .

Web client accelerator

As of July 2006, these applications generally serve to improve dial-up, broadband
Broadband
The term broadband refers to a telecommunications signal or device of greater bandwidth, in some sense, than another standard or usual signal or device . Different criteria for "broad" have been applied in different contexts and at different times...

 and other connections from which users may not be getting the best speed. Many users can achieve a 2- to 10-times speed increase in average browsing experience, while some report a 5- to 20-times speed increases for specific web sites and pages. Many ISPs offer web accelerators as a part of their dial up and broadband services. Web accelerators are typically designed for web browsing and, sometimes, for e-mailing and can not improve speeds of streaming
Streaming media
Streaming media is multimedia that is constantly received by and presented to an end-user while being delivered by a streaming provider.The term "presented" is used in this article in a general sense that includes audio or video playback. The name refers to the delivery method of the medium rather...

, gaming, P2P downloads or many other Internet applications. However, there is substantial work being done on client-side Web Accelerators for Application Delivery Networks by several companies including Cisco Systems and F5 Networks as the demand for SaaS and PaaS look set to grow among SMEs.

Comparison

Web client accelerator Compression Operating
system
Browser Caching Prefetching Optimize
code
Preemptive
hostname
resolution
Ad removal Client Connection Price
CACHEbox None Appliance (Linux) All Yes Yes No No Yes End user, ISP Broadband, Satellite, Wireless, Fiber, DSL Commercial
CProxy Gzip, images Windows All ? ? ? ? ? user up to 756kbps Free demo, full version 35USD per year
Fasterfox
Fasterfox
Fasterfox is a Mozilla Firefox extension that provides an interface to tweak some performance related settings such as browser network connection, cache, timings, as well as provide an optional controversial feature which forces Link prefetching. These changes can decrease page loading time...

None Windows, Mac, Linux and Mobile devices Firefox Yes Yes No No No user Dialup, Wireless, Broadband, DSL Free
fasTun Images, text & any gzippable data Any Any No No HTML
CSS
Yes Yes All Any Free
Freewire Images and email attachments Windows, except NT and 95 Internet Explorer 5.0 or higher ? ? No No No ISP Dial-up local rate
Google Web Accelerator
Google Web Accelerator
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...

 (discontinued)
Yes Windows Explorer, Firefox Yes Yes No No No user/Google server Broadband Free
Heigh Speed
Heigh Speed
Heigh Speed is a Web accelerator for Microsoft Windows operating systems. It works by changing settings in the Windows Registry that affect the way the operating system interacts with the network....

None Windows Any Yes No No No No All Any Commercial
Netfury Images, Text, Email, HTTP downloads Windows, Mac Explorer, Firefox, Opera, Netscape Yes No No No No End User, ISP Dial-up, Broadband, DSL, ISDN, Satellite, Wireless £24.99
Nitro Images, Text, Email, HTTP downloads Windows, Mac Explorer, Firefox, Opera, Netscape Yes Yes No No No End User, ISP Dial-up, Broadband, DSL, ISDN, Satellite, Wireless $29.95 a year
ONSPEED
OnSpeed
ONSPEED is a software program designed to accelerate an internet connection using compression techniques....

Text & Images & Flash & Office Docs Windows, Mac and Mobile devices Any No No No No No user Dialup, Wireless, Broadband, DSL $49.99 (US)
£24.99 pa
Free (for users of BT Yahoo! Dialup Internet in the UK)
Polipo
Polipo
Polipo is a fast and lightweight, forwarding and caching proxy server and computer software daemon.By virtue of being a compliant HTTP 1.1 proxy, Polipo has all the uses of traditional Web proxies. It features HTTP 1.1, IPv4 & IPv6, traffic filtering and privacy-enhancement. Polipo supports HTTP...

None Unix (Linux, *BSD, Mac OS X, others), Windows Any Yes No No No Yes user/ISP Any Free
Propel Images, Text, Email, PDF, HTTP downloads Windows, Mac Explorer, Firefox, Opera, Netscape Yes No No No No End User, ISP Dial, DSL, ISDN, Satellite, wireless $44.95 US per year. Free with many ISP subscriptions
Proxyconn Web Accelerator Text & Images & Flash & Office Docs Windows, Mac, Mobile devices Any Yes Yes No No No user Dialup, Wireless, Broadband, DSL $47.88 Yearly or $5.95 Monthly
RabbIT Images, text & any gzippable data Any system with Java 1.6 VM available Any Yes No No No Yes ISP Any Free
Squid None Unix (Linux, *BSD, Mac OS X, others), Windows Any Yes No No No No user/ISP Any Free
Toonel Text & Images Windows, Linux, Mac OS, Symbian, WindowsMobile Any No No No No No user/ISP Any Free
WinGate
Wingate
-Places:In New Zealand:* Wingate, New Zealand, A suburb of Lower HuttIn the United Kingdom:* Wingate, County Durham* Old Wingate, County Durham* Wingates, Bolton, Greater ManchesterIn the United States:* Wingate, Indiana...

Relies on origin Windows (2000 onwards) Any Yes No No No No All Any Commercial
Ziproxy
Ziproxy
Ziproxy is a forwarding, non-caching, HTTP proxy targeted for traffic optimization.The ziproxy software is regarded as lightweight in terms of memory and processing power consumption....

Images, text & any gzippable data Unix (Linux, *BSD, Mac OS X, others) Any No No HTML
Javascript
CSS
Yes Yes ISP Any Free

Web server accelerator

Other web accelerators are targeted at the web site or web application owners. This type of web accelerator is installed in front of web servers and application servers and use a variety of the above techniques to improve performance to all users accessing the accelerated web sites or web applications. Sometimes referred to as a Reverse proxy
Reverse proxy
In computer networks, a reverse proxy is a type of proxy server that retrieves resources on behalf of a client from one or more servers. These resources are then returned to the client as though it originated from the reverse proxy itself...

.

These type of server side accelerators has the added benefit of off-loading transactions and connection managements from the web or applications servers and hence, reducing its CPU utilisation and increasing web server or application scalability to handle more users with less bandwidth.

Comparison

Web server accelerator Compression Operating
system
Browser Caching Edge Side Includes Prefetching Optimize
code
Preemptive
hostname
resolution
Ad removal Client Connection Price
aiCache
AiCache
aiCache is an HTTP accelerator and load balancer designed to allow dynamic web pages to scale content by intelligently caching frequently requested content...

Gzip Linux All Yes No Yes Yes Yes ? All High Speed Commercial
CACHEbox None Appliance (Linux) All Yes No Yes No No Yes End user, ISP Broadband, Satellite, Wireless, Fiber, DSL Commercial
LotServer None Linux, Windows All No No No No No No Content Provider Any Commercial
Polipo
Polipo
Polipo is a fast and lightweight, forwarding and caching proxy server and computer software daemon.By virtue of being a compliant HTTP 1.1 proxy, Polipo has all the uses of traditional Web proxies. It features HTTP 1.1, IPv4 & IPv6, traffic filtering and privacy-enhancement. Polipo supports HTTP...

None Unix (Linux, *BSD, Mac OS X, others), Windows Any Yes No No No No No user/ISP Any Free
SiteCelerate Text & Images ? Any Yes No Yes No No No user/ISP Any Per CPU
Squid None Unix (Linux, *BSD, Mac OS X, others), Windows Any Yes Yes No No No No user/ISP Any Free
Varnish Gzip on-the-fly compression and decompression Unix (Linux, *BSD, Mac OS X, Solaris, others) Any Yes Yes (including stitching together compressed ESI
Edge Side Includes
Edge Side Includes or ESI is a small markup language for edge level dynamic web content assembly. The purpose of ESI is to tackle the problem of web infrastructure scaling. It is an application of edge computing....

 fragments)
No No No If You want. All Any Free. Commercial support and services are available.
Ziproxy
Ziproxy
Ziproxy is a forwarding, non-caching, HTTP proxy targeted for traffic optimization.The ziproxy software is regarded as lightweight in terms of memory and processing power consumption....

Images, text & any gzippable data Unix (Linux, *BSD, Mac OS X, others) Any No No No HTML
Javascript
CSS
Yes Yes ISP Any Free

Client–server

There may be two sections to the proxy as well - a server portion sits in front of the Web server
Web server
Web server can refer to either the hardware or the software that helps to deliver content that can be accessed through the Internet....

 and captures the input and output from the server and a client portion sits in front of the end-users Web Browser
Web browser
A web browser is a software application for retrieving, presenting, and traversing information resources on the World Wide Web. An information resource is identified by a Uniform Resource Identifier and may be a web page, image, video, or other piece of content...

to capture the input and output from the browser.

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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