Web accelerator

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

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.

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 small and medium enterprises.

Comparison

Web client accelerator	Compression	Operating system	Browser	Caching	Prefetching	Optimize code	Preemptive hostname resolution	Ad removal	Client	Connection	Price
Apache Traffic Server	with plugin	Linux, Unix-like									free
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 (no longer available)	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

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 proxies or Application Delivery Controllers.

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

Web server accelerator	Compression	Operating system	Browser	Caching	Edge Side Includes	Prefetching	Optimize code	Preemptive hostname resolution	Ad removal	Client	Connection	Price
aiScaler	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

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-user's web browser to capture the input and output from the browser.

External links

• Web Accelerators at DMOZ

References

Commercial Web Accelerators

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