血色衣冠项羽:Web accelerator

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Web accelerator

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A web accelerator is a proxy server that reduces web site access times. 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.

Contents

[hide]
  • 1 Techniques
  • 2 Web client accelerator
    • 2.1 Comparison
  • 3 Web server accelerator
    • 3.1 Comparison
  • 4 Client–server
  • 5 External links

[edit] Techniques

Web accelerators may use several techniques to achieve this reduction:

  • They may cache recently or frequently accessed documents so they may be sent to the client with less latency or at a faster transfer rate than the remote server could.
  • They may freshen objects in the cache ensuring that frequently accessed content is readily available for display.
  • They may preemptively resolve hostnames present in a document (HTML or Javascript) in order to reduce latency.
  • They may prefetch documents that are likely to be accessed in the near future.
  • They may compress documents to a smaller size, for example by reducing the quality of images or by sending only what's changed since the document was last requested.
  • They may optimize the code from certain documents (such as HTML or Javascript).
  • They may filter out ads and other undesirable objects so they are not sent to the client at all.
  • They may maintain persistent TCP connections between the client and the proxy server.

[edit] Web client accelerator

As of July 2006, these applications generally serve to improve dial-up, broadband 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, 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.

[edit] Comparison

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 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 (discontinued) Yes Windows Explorer, Firefox Yes Yes No No No user/Google server Broadband Free 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 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 None Unix (Linux, *BSD, Mac OS X, others), Windows Any Yes No No No No 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 Relies on origin Windows (2000 onwards) Any Yes No No No No All Any Commercial. Ziproxy Images, text & any gzippable data Unix (Linux, *BSD, Mac OS X, others) Any No No HTML
Javascript
CSS Yes Yes ISP Any Free Compression Operating
system Browser Caching Prefetching Optimize
code Preemptive
hostname
resolution Ad removal Client Connection Price

[edit] 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.

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.

[edit] Comparison

Compression Operating
system Browser Caching Prefetching Optimize
code Preemptive
hostname
resolution Ad removal Client Connection Price aiCache Gzip Linux All Yes Yes Yes Yes   All High Speed Commercial CACHEbox None Appliance (Linux) All Yes Yes No No Yes End user, ISP Broadband, Satellite, Wireless, Fiber, DSL Commercial Polipo None Unix (Linux, *BSD, Mac OS X, others), Windows Any Yes No No No No user/ISP Any Free SiteCelerate Text & Images   Any Yes Yes No No No user/ISP Any Per CPU Squid None Unix (Linux, *BSD, Mac OS X, others), Windows Any Yes No No No No user/ISP Any Free Varnish Relies on origin Unix (Linux, *BSD, Mac OS X, Solaris, others) Any Yes No No No No No Any Free. Commercial support and services available. Ziproxy Images, text & any gzippable data Unix (Linux, *BSD, Mac OS X, others) Any No No HTML
Javascript
CSS Yes Yes ISP Any Free

[edit] Client–server

There may be two sections to the proxy as well - a server portion sits in front of the Web server and captures the input and output from the server and a client portion sits in front of the end-users Web Browser to capture the input and output from the browser.

[edit] External links

  • Web Accelerators at the Open Directory Project
  • web application acceleration from aiCache
  • web application acceleration tools from Akamai
Retrieved from "http://en.wikipedia.org/wiki/Web_accelerator"Categories: Web acceleratorsHidden categories: Articles lacking sources from July 2009 | All articles lacking sources
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