PowerPoint Presentation - HTTP Caching and Cache-Busting for Content Publishers

Revalidation works well

•Apache handles revalidation for static content

–Browser sends If-Modified-Since request

–Server replies with short 304 Not Modified

–No special configuration needed

•Use if you can’t predict when content will change

–Page designers can change immediately

–No renaming necessary

•Cost: extra HTTP transaction for 304

–Smaller with Keep-Alive, but large sites disable


	Each HTTP request has some latency. When you disable Keep-Alive (as any large site typically must do to scale), each HTTP request requires a full 3-way TCP handshake. The handshake latency can be perceptible, especially on a slow connection such as a 56k modem.