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 or 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[edit]

Web accelerators may use several techniques to achieve this reduction in access time:

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.
  • freshen objects in the cache ensuring that frequently accessed content is readily available for display.
  • preemptively resolve hostnames present in a document (HTML or JavaScript) in order to reduce latency.
  • prefetch documents that are likely to be accessed in the near future.
  • 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.
  • optimize the code from certain documents (such as HTML or JavaScript).
  • filter out ads and other undesirable objects so they are not sent to the client at all.
  • maintain persistent TCP connections between the client and the proxy server.
  • improve the performance via protocol level accelerations, such as TCP acceleration.

These techniques align with best practices which are typically recommended to improve the performance of web applications.[1]

Web client accelerator[edit]

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 small and medium enterprises.

Comparison[edit]

Web client accelerator Compression Operating
system
Browser Caching Prefetching Optimize
code
Preemptive
hostname
resolution
Ad removal Client Connection Price
Apache Traffic Server Linux
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 756kbit/s 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
Heigh Speed 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 ($5.95 + tax per month in Canada)
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)
Opera Turbo Images, http header optimization and any gzippable data Android, Linux, Mac and Windows devices Opera Yes No No No No user/Opera server Any Free
Polipo 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
RabbIT4 Images, text & any gzippable data Any system with Java 1.6 or newer 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

Web server accelerator[edit]

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. Web server accelerators are sometimes referred to as reverse proxys or Application Delivery Controllers.[2]

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

Comparison[edit]

Web server accelerator Compression Operating
system
Browser Caching Edge Side Includes Prefetching Optimize
code
Preemptive
hostname
resolution
Ad removal Client Connection Price
aiCache Gzip Linux All Yes No Yes Yes Yes  ? All High Speed Commercial
Apache Traffic Server Linux
CACHEbox None Appliance (Linux) All Yes No Yes No No Yes End user, ISP Broadband, Satellite, Wireless, Fiber, DSL Commercial
Ishlangu Gzip Appliance (Linux) All Yes No No Yes Yes No All High Speed Commercial
LotServer None Linux, Windows All No No No No No No Content Provider Any Commercial
nginx Gzip Unix (Linux, *BSD, Mac OS X, Solaris, AIX, others), Windows Any Yes No No No Yes No user/ISP Any Free. Commercial support available.
Polipo 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 fragments) No No No If You want. All Any Free. Commercial support and services are available.
Ziproxy 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[edit]

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.

External links[edit]

References[edit]

  1. ^ Multiple (wiki). "Web application". Docforge. Retrieved 2012-12-13. 
  2. ^ http://aiscaler.com/what-is-an-application-delivery-controller-adc