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Re: Attributes in Prelim DAV Spec

From: Ben Laurie <ben@gonzo.ben.algroup.co.uk>
Date: Tue, 12 Nov 1996 21:54:23 +0000 (GMT)
To: Kenji Takahashi <kt@nttlabs.com>
Cc: masinter@parc.xerox.com, w3c-dist-auth@w3.org
Message-ID: <9611122154.aa02248@gonzo.ben.algroup.co.uk>
Kenji Takahashi wrote:
> 
> Larry,
> 
> >Suppose that a versioning-aware server just returns a LINK header, e.g.,
> >   GET http://www.cern.ch/TheBook/chapter2 HTTP/1.1
> >returns headers that include
> >   Link: <http://www.cern.ch/meta-repository/TheBook/chapter2>; rel="MetaData"
> >
> >and then the client will know that it can do GETs against 
> >the linked URL to get and modify the attributes of the included
> >URL. 
> 
> This is dangerous because attributes or something may change during two
> transactions.  For example, the content may be changed after the GET of
> the content and before the GET of the attributes.  This results in 
> the inconsistency between the contents and attributes.  So, I thingk
> the content and its attributes should be gotten in one transaction.

The proposed syntax provides a link between the URL and the metadata, without
saying what the metadata is. This means that unless the method for retrieving
the metadata changes, your argument does not apply.

The possibility that the retrieval method might change is worrying, though.

Cheers,

Ben.

> 
> How about the following (we are implementing this now).   The attributes 
> are sent as HTTP headers with the content with options.  To specify options, 
> I would like to propose "request-attributes" header for GET.  If this header 
> is not included in the GET request, attributes are not sent.  For example, 
> if you would like to get the "author" and "lock-state" attributes:
> 
> GET http://foo.bar.content
> request-attributes: author,lock-state, etc... 
> 
> If you need all the attributes:
> 
> GET http://foo.bar.content
> request-attributes: *
> 
> If you need only the attributes.
> HEAD http://foo.bar.content
> request-attributes: *
> 
> Also I would like to propose something like SET_ATTR to set 
> attributes.  Good symmetry, hah?
>   GET  <-> PUT
>   HEAD <-> SET_ATTR
> 
> Best regards,
> 
> Kenji
> 

-- 
Ben Laurie                Phone: +44 (181) 994 6435  Email: ben@algroup.co.uk
Freelance Consultant and  Fax:   +44 (181) 994 6472
Technical Director        URL: http://www.algroup.co.uk/Apache-SSL
A.L. Digital Ltd,         Apache Group member (http://www.apache.org)
London, England.          Apache-SSL author
Received on Tuesday, 12 November 1996 17:56:11 GMT

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