Subject: RE: HOW_TO_IDENTIFY_LOCK_OWNER

From: "Jason Crawford" <[email-masked]>
Date: Tue, 29 Jan 2002 15:53:55 -0500

<<
WebDAV explicitly states that servers and clients MUST ignore unknown
element.
FWIW.... By "ignore" I believe you are refering to section 14 and 23.3.2.2.
Taken together these sections suggest that "ignore" means that if a client
sends in an extra field in lockinfo, the field will be (and MUST be) thrown
away and not stored... but the server will not choke.

Simiarly... if for some reason a server passes back a new field, the client
MUST ignore it (as if it wasn't there) and not choke on it.

It's also worded in a way that a receiver is free to save/process a field
that it is familiar with even if it's not defined in the spec.  The pivotal
word here in my explanation is "familiar".  This provides elbow room for
new designs using new fields.

So... we know that all 2518 compliant servers will throw away any new field
of DAV:lockinfo we submit.  And that current 2518 compliant clients will
not choke if the server sends the extra field.  This means that a
transition strategy for adding a new field of DAV:lockinfo should be
straight forward and not cause old clients to break.

I believe that a new element within DAV:owner is a little different.  The
DTD definition for it is "ALL" so I doubt the above rules apply.  But after
our clarification, we know that the server will store whatever we put
there.  We just haven't defined the details of that round trip behavior.
Beyond that, we have to consider how current clients use what they find in
that field.   This might require some interop testing.

<<
1) The examples in RFC2518 do *not* preserve DAV:owner (watch out for
whitespace!).

2) We currently don't have a clear definition about *what* needs to
preserved as a property value (this is already on the issues list).
Whatever
applies to a property value should reply to the DAV:owner element as well.
I've updated my local copy of the issues list to reflect these too items.

I'll watch to see how discussion about contact-URL-list goes.

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