Subject: [Fwd: Re: PUT vs strong ETags]

From: Julian Reschke <[email-masked]>
Date: Tue, 29 Nov 2005 22:12:01 +0100

(fyi)

-------- Original Message --------

Wilfredo Sánchez Vega wrote:
>   Question for you.
> 
>   Apache HTTPD emits a weak etag for a file resource if the timestamp on 
> the file is the same as the current time (one second accuracy) and a 
> strong etag otherwise.
> 
>   The reason for that logic, as I understand it, is that because the 
> etag generation depends on the timestamp and that the file may change 
> multiple times within a one-second period, an etag generated from a 
> timestamp matching the current time isn't reliable.

Finally a good explanation.

>   But your post caused me to re-read the spec, and this logic doesn't 
> seem consistent with the spec.  The weak etag would be the same for all 
> changes in a one-second period but the documents may not be semantically 
> similar.  So that seems like a bug.  Perhaps HTTPD should instead omit 
> the etag in that case, since the etag isn't weak; it's simply not 
> correctly calculable using the timestamp.
> 
>   That sound right?

I think this is correct, and getting this question answered is essential
on how the working group tackles the various (new) ETag issues in
RFC2518bis.

May I forward this mail to the WebDAV mailing list?

Best regards, Julian

---

From: Lisa Dusseault <[email-masked]>
Date: Tue, 29 Nov 2005 13:43:15 -0800

On Nov 29, 2005, at 1:12 PM, Julian Reschke wrote:
>>   Apache HTTPD emits a weak etag for a file resource if the timestamp 
>> on the file is the same as the current time (one second accuracy) and 
>> a strong etag otherwise.

Do other people consider this behavior to be incorrect according to the 
spec?  (I'm assuming the explanation is correct and it aligns with what 
I've seen).  But it seems that within-second changes do not guarantee 
"semantic equivalence" as required by HTTP.

Lisa