What is Cache Control?

Posted: November 16th, 2009
Filed under: Web Speed and Performance
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What is Cache Control?

Cache control is not to be confused directly with caching itself, which is generally a special high-speed storage mechanism that can be either a reserved section of main memory or an independent high-speed storage device. Cache control is also different from caching in ASP.NET or PHP Web development technologies that focus on the pre-generation of DB queries so dynamic pages load faster for browsers. 

Cache control is about making a cache smarter on the Web, essentially turning browsers and proxy servers on the Net into your own content distribution network.  The idea is to send less data, less often by making sure repeat visitors and Internet caches from any proxy servers do not re-validate static, unmodified content like an image (GIF, JPEG, PNG, Bitmap, whatever), CSS style sheets, JavaScript, a video, a PDF, an .exe, etc. Microsoft IIS does not yet provide an “easy access” mechanism for developers or admins to manage cache control centrally for a Web server and its virtual servers or Web sites, so a tool like CacheRight makes sense for Web professionals with timelines, budget and speed in mind.

Spend (or save) Your Cache

Once you know what content you would like to apply cache control to, using CacheRight to control your cache is fairly straightforward:  write a rule, save the rules file, request resource and examine headers to see if the right Expiration-based cache control headers were applied (the Expires: header and other headers for caches).  Browsers and proxy caches then rely on this data to decide whether to ping your Web server for new content and to avoid 304s at the Web server – this means your Web server answers higher priority requests, and repeat visitors see your Web site or application faster every time they use it as images and non-changing files pop quickly from their CPU, from the browser’s cache – or a closer proxy server.

Final Thoughts

Keep customers on your site. Serve less data, less often. Control your cache with a web server product like CacheRight from Port80 Software.

~ Port80

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