Web accelerator

A web accelerator is a proxy server that reduces web site access times. They can be a self-contained hardware appliance or installable software.

[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] Location

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

[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] Client Side

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.

[edit] Server Side

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] Most Popular

Since there are so many different PC configurations, it is impossible for any one web accelerator to be the best as an application of its purpose. It is even possible for a web accelerator to slow down and clog up a connection.

[edit] Comparison

It is essential when selecting a web accelerator product that you take time to find the most suitable accelerator based on your needs and system setup. Not all accelerators will run on all operating systems and some may be optimised for a specific browser configuration.

It is important to check which internet connections the web accelerator is designed to work with. In some cases selecting the wrong product will reduce your internet connection speed dramatically.

The table below shows a number of web accelerators available:

[edit] External links

• Web Accelerators at the Open Directory Project

• Web Application Accelerator - web application acceleration tools from Akamai

• FAQ on hardware load balancing including HTTP acceleration