ETag

HTTP header tag helpful in RSS Scalability

Joe Gregorio http://bitworking.org/news/[[ETags__This_stuff_matters |example]] Bill De Hora links to some pieces on it.

• Tim Bray refines how to use it. What you want to do is compute the ETag based on the underlying data resources that actually drive the page creation; the input to that process, not its output. This is often going to be a small number (sometimes one) of timestamp or version fields in a database row, or metadata from the underlying filesystem. It's also going to be application-dependent. So a framework that was really designed for the Web would expose the ETag generation to the application programmer in a way that let them be smart about conserving the resources that actually matter.

• Mark Nottingham notes some issues, and that you might want to just consider alternatives like HttpConditionalGet.