On Tuesday 18 Jun 2002 2:15 pm, R. David Murray wrote:
RFC 2616 section 9.4 states that "HEAD" is identical to "GET" in this respect, and both should have no side effects.
This bugged me the first time this discussion went around, and I feel impelled to clearify it now, even though it is a little tangential to the core of the discussion. I guess I'm just a precisionist when it comes to terminology <grin>.
Yes, you are precisely correct. Thanks.
So it seems to me that some of the concern I have seen in Zope code with avoiding "write on read", where a GET request would otherwise trigger the one-time initialization of something in the database, is misplaced if the concern that motivates it is adhering to this spec.
Yes, I dont think this is a problem.
NB: There seems to be a small bug in the spec, in that it does not say that any sequence of GET and HEAD requests on the same URI should be idempotent, but that is clearly the intent.
PS: somehow, I don't think the spec writers thought much about hit counters...
I like the phrase 'largely idempotent' to refer to what we want from a GET or a HEAD. A page with a hit counter is 'largely idempotent'.