Subject: RE: Are you using lock discovery?

From: "Jason Crawford" <[email-masked]>
Date: Tue, 26 Jun 2001 22:12:36 -0400

<<
As I recall, the DAV Explorer client <http://www.ics.uci.edu/~webdav/> uses
lock discovery. I believe it's smart enough to do lock discovery if a
resource is locked, and DAV Explorer doesn't have the lock token. It then
tries the lock token on the off chance the requesting principal actually
owns the lock.
Just a tangent...

I'm sure Jim know this, but I'd just like to warn other client developers
that servers are not obligated to expose the lock-token in the
lock-discovery property.   Servers might chose not to expose the tokens so
as to avoid the situation described in section 7.6.  Make sure your clients
can handle a server not returning the lock token in the lock-discovery
property.

---

From: "Stefan Eissing" <[email-masked]>
Date: Wed, 27 Jun 2001 09:57:51 +0200

> [mailto:[email-masked]]Im Auftrag von Jason Crawford
>
> <<

Well, thanks for the warning. Which server(s) would that be? And will
they prevent a client application/operating system/network connection
from crashing or will they have another method to discover locks and
unlock resources?

Stefan

---

From: "Jim Whitehead" <[email-masked]>
Date: Wed, 27 Jun 2001 10:19:36 -0700

> as to avoid the situation described in section 7.6.  Make sure
> your clients can handle a server not returning the lock token in the
lock-discovery
> property.

Well, actually, this did take me a bit by surprise. But, after re-reading
Section 13.8, Jason is right, we do allow servers to hold back some elements
of the lockdiscovery property. But, the stated rationale is access control,
not keeping clients from grabbing lock tokens.

It seems to me the root issue here is how much you trust users to remove
their own locks. For DAV Explorer, we felt the people using the tool would
likely either be doing server development, or setup of a WebDAV server. That
it why we added the protocol logging feature to the tool. While DAV Explorer
is useful enough to accomplish some day-to-day editing work, we didn't think
that would be its main use (we were somewhat surprised to see DAV Explorer
get bundled with the Merlin server:
http://www.abriasoft.com/products/product16.php :-). Since we felt our user
base would be fairly sophisticated, we were comfortable giving them the
ability to grab locks that they took out using another program (and no, I
don't think DAV Explorer prompts the user about this).  This makes it a
handy protocol exploration tool. If you want to know exactly how tool X
performs when a lock is yanked out from under it, you can use DAV Explorer
to unlock the resource.

For more mainstream *authoring* tools, I agree completely that, if the user
is granted the ability to grab a lock, they should be shown a dialog box
about the event.  As for tools like Goliath that give a filesystem-like
view, I think a good case can be made either way (prompting or no
prompting). Perhaps it should be configurable, or the dialog should have an
option to not be displayed in the future.

- Jim