Subject: Re: Your proposal

From: "Eric Sedlar" <[email-masked]>
Date: Mon, 3 Jan 2000 13:09:22 -0800

Your proposalOne problem with your qualms about properties is that we are trying to map WebDAV data to object representation systems that do not have functional semantics, like XML.  We should define an interface that doesn't rely on the distinction between functional interfaces and properties for maximum implementability on various servers.  (This distinction is something may programmers have trouble with--does everyone always bother to create accessor methods for everything?  ...)  The benefit of using live properties as a representation is that object properties are more "portable" to the other types of systems that may want to access the same data, presumably through another means than the HTTP protocol (which isn't particularly efficient).  (Which brings me to another unrelated issue--should there be a functional interface to WebDAV methods for programs living in the same server as the data repository, given the performance costs of HTTP within a single process--more on that later).

Yes you need a set of clear rules for how live properties are used, and unless their use is rigorously controlled, you will have compatability problems of the type you cite, but this is a problem with any loosely written standard.
I think of properties in the JavaBeans sense--in an OO language binding, they would actually be functional interfaces to set and retrieve them, but could be overridden to provide customized behaviour.  Any JavaBeans user has no idea whether or not this piece of data is live or not, and this model works well.

--Eric
  ----- Original Message ----- 
  From: Yaron Goland 
  To: 'Eric Sedlar' 
  Sent: Monday, January 03, 2000 11:18 AM
  Subject: Your proposal

  Eric, I read your analysis of Geoff's proposal and was really impressed by your deep grasp of both HTTP and WebDAV. 

  I have a series of issues with your counter-proposal but I'm going to hold off on commenting until we can build up more of a common base for conversation. Please see my post on the mailing list in regards to this.

  I did, however, want to point out a general design issue regarding your proposal that isn't directly related to locks. In your proposal you suggest using properties to provide various bits of protocol information, such as which names are currently locked. I would caution against using properties in this way, see http://lists.w3.org/Archives/Public/w3c-dist-auth/1998OctDec/0302.html for more details. For a history of how we ended up in this mess in the first place see http://lists.w3.org/Archives/Public/w3c-dist-auth/1998OctDec/0074.html and http://lists.w3.org/Archives/Public/w3c-dist-auth/1998OctDec/0303.html. BTW, all of these posts are collected in the WebDAV Book of Why available at http://lists.w3.org/Archives/Public/w3c-dist-auth/1999JanMar/0129.html.

                  Thanks, 
                                  Yaron