RE: GET, POST, and side-effects

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