RE: Interest in standardizing Batch methods?

"Idempotent" doesn't mean "returns the same response",
it means "produces equivalent state on the server".
RFC 2516 makes this clear by explicitly identifying PUT
and DELETE as idempotent operations.

Cheers,
Geoff

-----Original Message-----
From: Stefan Eissing [mailto:stefan.eissing@greenbytes.de]
Sent: Wednesday, January 09, 2002 10:47 AM
To: Clemm, Geoff; WebDAV
Subject: RE: Interest in standardizing Batch methods?


> From: w3c-dist-auth-request@w3.org
> [mailto:w3c-dist-auth-request@w3.org]On Behalf Of Clemm, Geoff
> Sent: Wednesday, January 09, 2002 4:17 PM
> To: WebDAV
> Subject: RE: Interest in standardizing Batch methods?
>
>
> A single MOVE, DELETE, or PROPPATCH request is idempotent
> (repeating the same request multiple times produces the
> same result as just doing it once).

Not quite: A second MOVE/DELETE/PROPPATCH will return a
different result to the client. So a second DELETE will
answer 404 instead of 204.

The server "state" will stay the same. I think that's
what you had in mind.

> A sequence of DELETE's is always idempotent.  A sequence of PROPPATCH's
> is always idempotent if the same property isn't updated by different
> PROPPATCH requests in that sequence.  A sequence of MOVE's is always
> idempotent if none of the Destination URLs overlap with any of the
> request URL's.
>
> Cheers,
> Geoff
>
>
> -----Original Message-----
> From: Julian Reschke [mailto:julian.reschke@gmx.de]
> Sent: Wednesday, January 09, 2002 3:34 AM
> To: Lisa Dusseault; Greg Stein; Jim Whitehead
> Cc: WebDAV
> Subject: RE: Interest in standardizing Batch methods?
>
>
> Looking at RFC2616:
>
> "8.1.2.2 Pipelining
> Clients SHOULD NOT pipeline requests using non-idempotent methods or
> non-idempotent sequences of methods
> (see section 9.1.2).
>
> So it seems that pipelining wouldn't be allowed for anything
> except PROPFIND
> (MOVE/DELETE/PROPPATCH aren't idempotent), right?
>
> > -----Original Message-----
> > From: w3c-dist-auth-request@w3.org
> > [mailto:w3c-dist-auth-request@w3.org]On Behalf Of Lisa Dusseault
> > Sent: Wednesday, January 09, 2002 6:30 AM
> > To: Greg Stein; Jim Whitehead
> > Cc: WebDAV
> > Subject: RE: Interest in standardizing Batch methods?
> >
> >
> >
> > > Personally, I'm going to guess they didn't pipeline requests,
> so a batch
> > > mechanism was a must to get around deficiencies in their
> protocol stack.
> >
> > There's potentially a little more to it than that.
> > (1) Imagine a client selects a bunch of resources and drags to
> > move them all
> > to a different folder.  A batch MOVE operation can do those in one
> > transaction, so that the whole request fails if not all can be
> > moved.  This
> > becomes rather more important if the client is actually using an API
> > (MSDAIPP??) that offers large-scope operations, yet how can it guarantee
> > that operation will work or won't work if it can only send it
> piecemeal to
> > the server?
> >
> > (2) See Yaron's email
> > (http://lists.w3.org/Archives/Public/w3c-dist-auth/1998OctDec/0303.html)
> > about why pipelining doesn't always work (can't always be used even when
> > available).  I don't know to what extent pipelining is realistically
> > unavailable/unworkable.
> >
> > That said, it's still not clear batch methods are so necessary they'd
> > preempt other work we've got to do.
> >
> > Lisa
> >
>
>
>

Received on Wednesday, 9 January 2002 12:19:01 UTC