(2007-03-22) Gregorio Etag Details

Joe Gregorio gives great details on ETag support (for ReST). Aside: Many of the things I'm talking about with ETags and If- headers can also be done with a last modified time served in the Last Modified: header. In general I advise against using Last-Modified: since it is limited to a one second granularity and you may have issues with clock skew among a group of servers. ETags are just conceptually simpler and just as powerful. This advice is only really for servers, which can decide which cache-validators to support, clients have no such luck and should support both. He builds some code on top of Robaccia.