- From: Werner Donné <werner.donne@re.be>
- Date: Mon, 07 May 2007 09:40:28 +0200
- To: w3c-dist-auth@w3.org
- Cc: acl@webdav.org
This is a matter of concurrency control. If we compare it to SQL transactions, then using a lock corresponds to the isolation level SERIALIZABLE. Without a lock it corresponds to READ COMMITTED. There is no general rule as to which isolation level is best in all circumstances. If the matter is left to the client there is no guarantee of serializability, because some client may not use a lock. This can lead to schedules like this: PROPFIND1 LOCK2 PROPFIND2 ACL2 UNLOCK2 ACL1 A possible way to enforce serializability is for the server to return an exclusive write lock with a short time-out in the PROPFIND response. The ACL method would only succeed if the lock token is present and the ACL method would implicitly release the lock. If another client performs a PROPFIND for the "acl" property between both operations, it will not get an implicit lock. The second client would be required to do a new PROPFIND if it wants to perform an ACL. Otherwise it was just consulting the "acl" property. Werner. -- Werner Donné -- Re Engelbeekstraat 8 B-3300 Tienen tel: (+32) 486 425803 e-mail: werner.donne@re.be
Received on Monday, 7 May 2007 07:40:16 UTC