Re: [ACL] RFC 3744: Modifying ACEs

On 5/6/07, Werner Donné <werner.donne@re.be> wrote:
> I have also a remark about the third paragraph of section 8.1, which
> says:
>
> "In order to avoid overwriting DAV:acl changes by another client, a
> client SHOULD acquire a WebDAV lock on the resource before retrieving
> the DAV:acl property of a resource that it intends on updating."
>
> This doesn't add any value, because you can't modify individual ACEs
> due to the lack of an addressing method. If the "acl" property
> is always updated completely a lock is not needed. Any client with
> the appropriate permissions can overwrite the property after the
> lock has been released.

I believe the lock is necessary because the acl property *is*
completely overwritten.  To make a change, a client must first read
the acl property.  To ensure that it does not overwrite someone else's
change when writing the acl property back, the client should grab a
lock.  Otherwise, another client could have changed the acl property
between the first client's PROPFIND and ACL requests.

-Tim