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Re: [Ietf-caldav] Last Call comment on Etag requirements in draft-dusseault-caldav-12

From: Lisa Dusseault <lisa@osafoundation.org>
Date: Tue, 20 Jun 2006 08:11:47 -0700
Message-Id: <5B9360D3-01CB-477F-AE25-640AB5F4BCC4@osafoundation.org>
Cc: Wilfredo Sánchez Vega <wsanchez@apple.com>, ietf@ietf.org, Ted Hardie <hardie@qualcomm.com>, CalDAV DevList <ietf-caldav@osafoundation.org>, HTTP Working Group <ietf-http-wg@w3.org>
To: Julian Reschke <julian.reschke@gmx.de>

Xythos WFC and Chandler (the Zanshin library that does WebDAV in  
python) behave this way and make the assumption I describe.  How else  
would you expect a caching or synching client to behave after doing a  
PUT, when the implementors of those clients were pretty sure that  
WebDAV servers stored the content without mucking with it?

Your turn now:  do you have an example of a general-purpose (e.g.  
file sharing, site synch)  shipping client that handles ETags and  
caches or synchronizes content, which does a full GET of the content  
immediately after PUT even if it receives a strong ETag?

Even if there are such clients, the behavior we describe avoids nasty  
errors on both such clients and clients like WFC.  It's the  
conservative choice.


On Jun 19, 2006, at 12:41 PM, Julian Reschke wrote:

> Lisa Dusseault schrieb:
>> On Jun 15, 2006, at 9:32 AM, Wilfredo Sánchez Vega wrote:
>>>   I agree with Julian.
>>>   As we've mentioned before, Apache returns a weak ETag on PUT,  
>>> which turns into a strong ETag sometime later.  If clients rely  
>>> on being able to use that ETag on a GET later, they won't work  
>>> with Apache, and IIRC, Apache is pretty popular.
>>>   The ETag requirements in the draft are what many clients  
>>> authors might *like* to be the common case, but it is most  
>>> certainly not so today.
>> It's worse than that; many client authors *assumed* that to be the  
>> case, and implemented and deployed their clients assuming that if  
>> the client receives a strong ETag in response to a PUT, it has no  
>> further work to do to synchronize that resource.  So the deployed  
>> base says that *is* the case today.  I don't feel our document  
>> makes this situation any worse than the deployed base of clients  
>> already does.
>> Lisa
> Again: do you have any evidence of *shipping* clients making that  
> assumption?
> Best regards, Julian
Received on Tuesday, 20 June 2006 15:11:56 UTC

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