What does Application acceleration mean?

Advanced Load balancers have been around for some time, but there still seems to be a lot of confusion over the loosely used term “Application Acceleration” .

Ok, so you have heard the hype and read the sales material, but what does acceleration actually mean in real life? What real benefits can you expect to see and more importantly, what difference will it make for your customers or users?

The four main areas of acceleration are:

• Compression
• Connection Management
• Content Caching
• SSL Acceleration

This first blog (of 4) takes a look at HTTP Compression.

Compression:

Web pages are very compressible. Typically an average web page, whether it is dynamically generated or static content, can be reduced in size by 80-90%. Nearly all browsers can accept the compressed content automatically without the end user having to make any changes; i.e. no end user browser plug-in is required (it is naively supported as part of the HTTP 1.1 protocol definition).

This ability to send compressed HTTP data over the net has been around for years but it has still not been fully exploited and in many cases it can be misunderstood. This is partly because of the CPU power required to compress dynamic web pages and the unpredictable compatibility with early browsers.

Typically compression is used to compress the text based parts on a page i.e. java script, HTML, XML, CSS etc. Images such as JPG, PNG etc are already compressed; as such they see very little benefit from additional compression.
However, it is dangerous to assume that compression will have little positive effect if your site is image rich. Firstly, the images can't be displayed until the base page arrives at the client, so it follows that the quicker you can deliver the base page, the faster you can request the objects and the quicker the page can load.
Secondly, web sites and applications generally have a consistent look and feel. As such the effect of client side caching is significant. This means that most of the data that will be sent is compressible as most of the images are already saved at the client side.


Compression in real life.

This screen shot was taken from the GUI of a jetNEXUS ALB-X in action at an e-commerce customer's site. (You should see similar levels of compression with most of the top end vendors). The “Content Compression to Date” is 85%. This means that out of the content that can be compressed, the average level of compression is 85%. Only 164GB out of the 1126GB was sent.

The “Overall Compression to Date” is 81%. This number should equate to your bandwidth usage, assuming that all your traffic is from the ALB-X. In this example most of the traffic is compressible, as such the overall reduction in bandwidth is 81%. 1.17TB would have been sent but only 0.25Tb was actually sent.


Optimization rating ***** Compression will offer the easiest and most effective way to speed up your web application, especially if the distance between you and your users is great or you are working with a slow WAN connection. In addition, because you will be serving your users faster in a fixed amount of time, you can serve more of them and therefore experience a significant capacity increase - especially during peak periods where it’s needed most