Hacker News Reader

This is also known as key-based cache expiration, detailed by DHH here: https://signalvnoise.com/posts/3113-how-key-based-cache-expi...

You never worry about when to expire your cache entries if the key changes every time the item does. It's nice to finally see cache-busting coming out of the woods.

View on HN

You can already use that kind of cache expiration with HTTP of course, and many of us do -- but you can't _tell the user-agent_ or other client that you are using it. The best you can do is set a far-future expires date. Some agents/clients will still do HEAD/If-Modified-Since requests to check if it _really_ changed before your expire date.

So this is a new thing, properly called immutable responses, to tell the client that they really can treat this (in various ways) as a completely immutable response.

Reply on news.ycombinator.com