Over at rsscache they have a way of refreshing the cache only when the feed has changed. Unfortunately its .Net.
I would like to know what approach I should take to achieve this in php.
How are changes in the feed detected? Simply by a timestamp (time node in the beginning of the feed)?
My feed would be a yahoo pipe that has mixed many feeds together. So either the yahoo feed must generate a combined timestamp, or my cache mechanism must automagically detect if the pipe has changed.
You have to:
Last-modifiedheader).If-modified-since).The server will either respond with
200(OK) and the content or304(Not Modified) and an empty response body.See RFC 2616.