Re: target selector again & again

Geoffrey M. Clemm (geoffrey.clemm@rational.com)
Sat, 23 Oct 1999 17:35:41 -0400 

Date: Sat, 23 Oct 1999 17:35:41 -0400
Message-Id: <9910232135.AA23948@tantalum>
From: "Geoffrey M. Clemm" <geoffrey.clemm@rational.com>
To: ietf-dav-versioning@w3.org
In-Reply-To: <1999Oct07.094400.1250.1344836@otismtp.ott.oti.com>
Subject: Re: target selector again & again

   From: Tim_Ellison@oti.com (Tim Ellison OTT)

   <geoff>
	In particular, if we define the "XML" form of DAV:history
	property resource suitably, a client will be able to obtain
	the revision URL in a single PROPFIND request on the
	versioned resource.
   </geoff>

   <tpe> i.e.

   PROPFIND myresource
   <propfind>
      <prop>
	 <dav:history/>
	 <dav:revision-id/>
      </prop>
   </propfind>

   </tpe>

You have to tell PROPFIND which property resource to expand,
and which properties of that property resource to display:

PROPFIND myresource
<propfind>
   <prop>
      <dav:expand-property-resource>
         <dav:versioned-resource/>
         <dav:revisions/>
      </dav:expand-property-resource>
   </prop>
</propfind>

   <tpe>
   Now this is where it gets surreal :-)

But in a good way (:-).

   The history property contains an XML representation of a history resource 
   that has a revisions property.

Actually, the versioned-resource property (AKA the history property)
contains an href to the versioned resource, but that you can ask PROPFIND
to recurse into the resource named by that href.  In this case, you're
asking it to return the DAV:revisions property.

   This makes the revisions property a 
   pseudo-prop (since it cannot be singularly retrieved by a PROPFIND; it is 
   embeddd in a dav property).

It can be retrieved either way, so it's more of a "super-prop" than
a "pseudo-prop" (:-).

   A client always has to retrieve the entire history resource even if it only 
   wants a single part of it.
   Is this right?
   </tpe>

Not if it uses the <dav:expand-property-resource> element in a PROPFIND
request.

It's at this point that one of my colleagues at work is known to
remark "you just made that up, didn't you".  But no really, I
made this up a while ago ... notice the <dav:expand-property-resource>
mentioned in the 02 spec (:-).

Cheers,
Geoff