Back to basics
 
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Lately I have been getting quite a few requests from readers for basic information on Web acceleration gear.
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In past newsletters, I've talked about a broad range of products, both hardware and software, and some of the drivers behind them. For newbies, I thought it would be helpful to put together a sample of what's out there. Please keep in mind that these definitions are short takes on some very complex technology.
The cache
A cache - as it relates to Web acceleration - is really just an application-specific storage device. Content caches combine hardware and software, though some vendors offer just plain software to do the job. The cache acts as a mechanism for distributing popular content.
The driver for using caches is that they store content that is ready for delivery. They can be deployed in front of Web server farms, or out on the edges of content delivery networks, closer to surfers - allowing sites to give faster response times. One of the key advantages to using a cache is that it eliminates the need for more expensive Web servers to assemble Web pages repeatedly, which is a process that can be slow and inefficient.
A static cache distributes content that doesn't change. A dynamic cache can distribute content that changes.
The load balancer
A load balancer's primary function is to make sure that requests for content or applications are distributed to a device that can handle the request. For example, a load balancer placed in front of a Web server farm would determine which server is most able to handle that request based on current load and availability.
Using a load balancer helps prevent any one device from being deluged while others sit idle. It also prevents requests from being routed to a device that isn't working. At the end of the day, response time should be better.
The traffic manager
A traffic manager is tied intimately to load balancing. It is more sophisticated, however, in that it determines where to send a request for content or an application based on the type of request.
For an online site, traffic management is critical. For example, if your e-commerce site has a premium subscriber list - people who pay to get certain content - you may want their requests to be handled by servers that are separate from the set serving non-paying users. Traffic managers also can help keep traffic flowing by allowing network managers to designate server farms for certain types of content, spreading the load more evenly.
The SSL offload device
The Secure Sockets Layer (SSL) offload device processes secure transaction computations, taking a big load off of Web servers. As more traffic becomes secure in nature and more people look to the Web to buy, SSL offloaders can help process requests more quickly.
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