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Showing posts from September, 2006

On Magic

We discovered an interesting IE6 feature when we pushed out caching changes earlier this week for Journals.  For posterity, here are the technical details.  Our R8 code started using "conditional GET" caching, meaning that we supported both If-Modified-Since: and If-None-Match: HTTP headers.  The way this works is that, if a client has a version of a page in its cache, it can send one or both of these headers to our servers.  Like this:
If-Modified-Since: Tue, 26 Sep 2006 21:47:18 GMT
If-None-Match: "1159307238000-ow:c=2303"If-None-Match, which passes an "entity tag" or ETag, is better to use and was designed to replace the If-Modified-Since header.   (If-Modified-Since has granularity only down to a second, and can't  be used to indicate non-time-based changes.)  In our case we actually have two versions of our pages which can be served up, one for viewers and another one for owners.  We really only want to cache the viewers' page.

When our server s…