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Re: WebDAV methods: safe and idempotent

From: John Stracke <francis@ecal.com>
Date: Wed, 11 Aug 1999 14:20:51 -0400
Message-ID: <37B1BF03.CC9D1B34@ecal.com>
To: WebDAV WG <w3c-dist-auth@w3.org>
Jim Whitehead wrote:

> Off-list, I was asked about the "idempotence" and "safety" of WebDAV
> methods [...] (Basically, "safe"
> = does not harm the state of the resource, "idempotent" = the effect of N >
> 0 identical requests is the same as a single request) [...]
> PROPFIND: safe, idempotent
> PROPPATCH: unsafe, idempotent

...*provided* you're not using any funky live properties.  Live properties are
behavior, not state, so they have safeness and idempotency, too.  So, really,
you have to assume that both PROPFIND and PROPPATCH are unsafe and
non-idempotent unless you know the safeness and idempotency of all the
properties in use.

(This is the same issue as CGIs in base HTTP/1.1; a CGI script could be built
that reacts unsafely to GET, but it wouldn't be HTTP/1.1-compliant; it's
supposed to use POST if it's unsafe.  But we don't have PROPFIND-GET and

|John Stracke    | My opinions are my own | S/MIME & HTML OK  |
|Chief Scientist | NT's lack of reliability is only surpassed |
|eCal Corp.      |  by its lack of scalability. -- John Kirch |
Received on Wednesday, 11 August 1999 14:21:02 UTC

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