I had an interesting discussion with a coworker about on which systems certain application logic should lie. In this case, our dialog revolved around whether an HTTP Redirect  should lie on a Web Server or on an F5 Application Delivery Controller. Naturally, being the ADC guy, I would want it on my system. Even with that said, I think it’s pretty obvious that logic like this should lie on the F5 device.

1. The F5 is closer to the user than the web server. If the F5 handles the redirect, the Web server doesn’t have to see the initial request, just the post-redirect one.

2. Instead of the redirect existing on multiple servers, it only has to exist on 1 (or 2) F5 devices.

Today, when most people discuss serving content on the “edge” or “closer to the customer,” they’re likely saying so because of the performance implications. The initial motivation for companies to utilize CDNs like Akamai  was to reduce dependence on their own infrastructure. By offloading static content to a CDN, companies could reduce their bandwidth costs and potentially even their server footprint. As demand for content-rich applications has increased, the main motivation for utilize a CDN has changed. The price of bandwidth has dropped dramatically while server consolidation technologies like Virtualization and Blades has made server resources cheaper than ever. Now, when a company chooses to utilize a CDN, it’s likely so its content can be even closer to its clients/users. Using technologies like Geographic Delivery, a user requesting a page from California can get sent to a CDN’s resource in California. This helps to deliver the rapid response time users have come to require out of new web applications.

There’s really no disputing that compression, caching, security, and redirects should be done as closer to the user as possible. The only potentially valid argument I see for not utilizing such services is a financial one. In retail, customers demand fast response times. In some environments, that isn’t the case. If users are apathetic to load time, then the optimal cost-effective solution would likely be one that doesn’t require a CDN at all…it’s all about finding out which solution fits best for your environment.

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