- From: Paul Leach <paulle@microsoft.com>
- Date: Thu, 4 Jan 96 17:48:03 PST
- To: sjk@amazon.com
- Cc: http-caching@pa.dec.com, mogul@pa.dec.com
Shel says: ] OK, so the problem at hand, then, is how to represent the information ] that a POST to the sine server has no side effects, whereas a POST ] to the sine-and-apple-pie-server does have side effects. ] (I always wanted to specify my pie servings in radians...) Exactly. ] ] I am certainly open to alternative representations of this. ] ] > ] > What is needed ] > ] is a way to clearly indicate in a *request* (not in responses) that ] > ] the request may be served from a cache, or must go through to the ] > ] origin server. (See my earlier posts). ] > ] > This I disagree about. It seems clear to me that only the server knows ] > whether the POST will have side effects, and that identical requests ] > return identical results. It seems easy enough to have the server ] > indicate that on the response to a POST, and I don't see how the client ] > could know. ] ] Ultimately, I agree that the server knows best. If you can come up ] with a better idea than mine for how to control this I'm all ears. ] ] Some additional header in responses that told caches how to deal with ] subsequent requests might work ... we'd have to work out the details. ] ] ] (...late breaking synaptic activity:...) ] I just got an idea that might be simpler than trying to control this ] using headers, and doesn't require convincing any HTML people of ] anything. Just invent some new methods that implement ] side-effect-free versions of POST, etc. ] Then we can define the cache actions differently based on ] the method. If it turns out that the client side can know to use these, fine. If the server is really the only one that can certifiy that (e.g.) a POST is side effect free, then this won't help. Paul
Received on Friday, 5 January 1996 01:53:05 UTC