Coming late to the party on this thread... On Nov 14, 2006, at 11:18 AM, Alexey Melnikov wrote:
I don't have a good opinion on this for IMAP, but I can say that in WebDAV, both server-generated and client-generated properties are offered in the same way. There are variations which are interesting too, as you note wrt a grey area: - properties which the client *can* change but not through the normal method: the ACL property is one example, being set with a complicated ACL method that allows adding and removing access control entries, and with a separate method so that firewalls/servers can audit/monitor. - properties which neither the core server nor the client change, but which change through some extension to the WebDAV server, installed or hacked-up by the administrator to use a server API to control the value - properties which are set by the administrator and never changed automatically by the server code, nor by clients. All of these are queried the same way, and there definite advantages in the long run to that. Features to ask "What properties are known to be supported?" work for all properties. Any mechanism to add datatyping works for all properties, "calculated" or not. A flag for "protected" can be added to any of these so that the server can enforce no changes over the wire. Searching each property can be turned on or off according to server capabilities. One of the best things IMO is that clients can treat all properties the same. You don't have to add *any* client code to query a new property if the client GUI is appropriately generic -- the user simply lists the available properties and chooses which ones to view or add to the user's regular views of their data. So if the server puts useful "Who updated this last" properties onto the files in my file share, I can add this to my file viewing tool without upgrading its code.
I believe this is true, but: - is everybody doing POSTADDRESS going to do METADATA anyway? - Is it possible to support METADATA without allowing clients to write and create their own properties? My personal opinion on POSTADDRESS at a higher level is that it's a little dangerous either as metadata or as list extensions -- I think Philip was the other one who pointed out that attackers could use it to place emails directly in folders other than your Inbox. Lisa |