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DAV props -- how to proceed?

From: Ben Collins-Sussman <sussman_at_collab.net>
Date: 2001-07-07 00:34:58 CEST

WebDAV/deltaV has the same notion of metadata that Subversion
does... and even calls them "properties" too.

The difference is that deltaV has two subcategories of properties:
"live" props are completely defined by the server, and "dead" props
are defined by users. "live" props are read-only to users.

Let's look at requirements.

 * Requirement #1: the dav layer has a lot of bookkeeping to do; it
   wants to store its own 'live' props on *every* version of each file
   and directory in the repository.

 * Requirement #2: the dav layer needs to store contextual properties
   in the working copy, such as which activity to commit to, and the
   versioned-resource-url of each working copy object.

     ==> This requirement has already been solved by giving each RA
     layer the ability to store "secret" properties called "wc
     props.". They are completely invisible to the user.

 * Requirement #3: the repository itself wants to automatically attach
   properties to certain things (like transactions and revisions.) It
   has no notion, however, of "live" vs. "dead". Even properties it
   creates, like a revision datestamp, can be edited by any user of
   libsvn_fs.

So here are the questions on my mind:

  * Are users supposed to see all the 'live' props (from requirement #1)
    inserted by the DAV layer? I don't think they should just
    casually show up in the working copy when a user types "svn
    proplist foo.c".

  * Assume we want to hide them. Fine. Then they'll be stored as
    secret "wc props". But that means *every* RA layer needs to
    filter them out when reading the repository (so they can be stored
    differently on the client side.) Isn't this icky?

  * To what extent should live props be visible at all? Is there ever
    a case where we would want to augment 'svn proplist' to show us
    all of the hidden, read-only live props?

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Received on Sat Oct 21 14:36:33 2006

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