- From: Dylan Barrell <dbarrell@bb.opentext.com>
- Date: Tue, 5 Aug 1997 04:30:15 -0400
- To: "'Whelan, Dan'" <dan@filenet.com>, "'Dylan Barrell'" <dbarrell@bb.opentext.com>, "w3c-dist-auth@w3.org" <w3c-dist-auth@w3.org>, "'Yaron Goland'" <yarong@microsoft.com>
What is the advantage to be gained from distinguishing between a single resource (whos arbritrator does not have to be "located") and multiple resources (whos arbritrator[s] has to be located first)? Cheers Dylan ---------- From: Yaron Goland[SMTP:yarong@microsoft.com] Sent: Montag, 4. August 1997 20:04 To: 'Dylan Barrell'; 'Whelan, Dan'; w3c-dist-auth@w3.org Subject: RE: Requirements Open Issues from Orem There is an arbitrator for single resources, the resource itself, it is kind enough to lock itself on your behalf. A server could configure itself such that every resource can serve as a lock arbitrator for all resources on that server. Yaron > -----Original Message----- > From: Dylan Barrell [SMTP:dbarrell@bb.opentext.com] > Sent: Monday, August 04, 1997 12:52 AM > To: 'Whelan, Dan'; w3c-dist-auth@w3.org; Yaron Goland > Subject: RE: Requirements Open Issues from Orem > > Having an arbitrator for locking multiple resources and the server for > locking single resources is very contrived and doesn't make sense. The > locking part of the standard is anyway optional (the single axis of > negotiation) so if a server doesn't want to implement it it doesn't > have to but if it does then WebDAV should specify a consistent > standard method by which this can be implemented. If you want an > arbitrator for locking multiple resources then it should be used for > locking single resources too. > > Cheers > Dylan > > ---------- > From: Yaron Goland[SMTP:yarong@microsoft.com] > Sent: Mittwoch, 30. Juli 1997 21:03 > To: 'Whelan, Dan'; w3c-dist-auth@w3.org > Subject: RE: Requirements Open Issues from Orem > > I suspect we will end up with a LOCK implementation where you have the > concept of a LOCK arbitrator who accepts a list of resources to be > locked and then locks them on your behalf in an atomic fashion. Of > course this means discovering who the lock arbitrator is for all the > involved resources, assuming one arbitrator can cover them all. > Alternatively one can discover what arbitrators exist for a particular > server and what namespaces they cover on that server. Either way, I > suspect most folks will simply lock each resource individually. > > Yaron > > > > > -----Original Message----- > > From: Whelan, Dan [SMTP:dan@filenet.com] > > Sent: Wednesday, July 23, 1997 10:50 PM > > To: w3c-dist-auth@w3.org > > Subject: RE: Requirements Open Issues from Orem > > > > I view the proposal to use containers to implement multi-resource > > locking as > > a somewhat clumsy way to satisfy this requirement for a number of > > reasons > > including: > > > > 1. The principal may not be authorized to create a container, or to > > file a > > resource in a container, and hence could not use this mechanism > to > > perform a multi-resource lock even if he was authorized to lock > > each of > > the resources. > > > > 2. Creating a transient container in order to obtain a > multi-resource > > lock > > is relatively inefficient, requiring O(2N) operations. > > > > 3. Servers may elect to implement only session based locks or short > > lived > > timer based locks to provide robust services in an otherwise > > unreliable > > environment. In such cases, a client is just as likely to fail > to > > remove > > a transient container as he is to unlock a lock yet the server > has > > no > > WebDAV sanctioned way of removing these transient containers. > > > > I'd prefer to see the LOCK and UNLOCK methods take an ordered list > of > > resources > > to LOCK or UNLOCK respectively. (I'm not familiar enough with HTTP > to > > know if > > the protocol makes passing a list of resources difficult -- WebDAV > has > > already addressed > > multi-status responses for the COPY, MOVE and DELETE methods) > > > > Dan Whelan > > FileNet > > Corporation > > ---------- > > From: Judith Slein[SMTP:slein@wrc.xerox.com] > > Sent: Monday, July 21, 1997 12:33 PM > > To: w3c-dist-auth@w3.org > > Subject: Requirements Open Issues from Orem > > > > A new version of the requirements draft will be submitted to the > > IETF on > > Thursday, 7/24. Your comments on these issues discussed at Orem > > will be > > helpful. > > > > ------------ > > > > Multiple Resource Locking > > > > As a result of the discussion at Orem, I was asked to raise the > > issue of > > atomic locking of multiple resources to the mailing list one > > more time. > > > > In an informal vote by those present for the discussion, 9 voted > > to keep the > > requirement, 4 to remove it. The rest (about 10 others) did not > > vote. > > > > At the moment, the requirement reads as follows: > > > > 5.3.1.2. Multi-Resource Locking. It must be possible to take out > > a > > lock on multiple resources residing on the same server in a > > single action, > > and this locking operation must be atomic across these > > resources. > > > > ("residing on the same server" was added at the request of the > > group at Orem.) > > > > The rationale for the requirement is to prevent livelocks. That > > is, if the > > requirement is not satisfied, it will be possible for 2 > > principals to try to > > lock the same group of resources, and for neither to get all the > > locks he > > needs. Each may end up with only some of the locks he needs. In > > addition, > > the requirement is meant to lessen the burden on the server that > > would be > > caused by multiple individual lock requests. > > > > The current locking draft does not satisfy the requirement. The > > difficulty > > is that it defines a LOCK method where the request URI is the > > resource to be > > locked. If we tried to accommodate multiple URIs by moving them > > into the > > body of the request, it is not clear what request URI would be > > appropriate. > > > > One suggestion was that the user put all the resources to be > > locked into a > > container, and then lock the container. The server would be > > required to > > treat the lock request as atomic to whatever depth was > > requested. > > > > ------------ > > > > The requirement concerning EMail transport will stay as is. > > > > ------------ > > > > Internationalization > > > > The consensus of the group at Orem was that we should stay away > > from issues > > around variants, which are not specific to internationalization > > and would > > add enormously to the work of WEBDAV. Jim will make sure that > > this position > > is acceptable to the area directors. > > > > The question was raised whether we need to be concerned about > > collation. We > > think that we do not -- we do not sort any query result sets, > > and we do not > > define greater-than or less-than operators for pattern matching. > > > > We think that we need only to insure that any information > > intended for user > > comprehension should be expressed in a way that makes it > > possible to display > > the information in any desired writing system and language. The > > proposed > > internationalization requirement is the following: > > > > "All information intended for user comprehension must be > > expressed in one of > > the ISO-10646 character sets and must have a language tag." > > > > ------------ > > > > Reservations > > > > The consensus of the group at Orem was to leave the reservations > > section > > separate, as it is now, and to continue to use the same > > terminology. The > > locking draft will discuss the standard use of the word > > "reservation" and > > explain how the shared lock satisfies the need for reservations. > > > > The language of 5.4.1.1 will change to make it clear that the > > point of > > reservations is to inform other users, not the server, of an > > intent to edit. > > The new 5.4.1.1 will say: > > > > "It must be possible for a principal to register with the server > > an intent > > to edit a given resource, so that other principals can discover > > who intends > > to edit the resource." > > > > ----------- > > > > --Judy > > > > Name: Judith A. Slein > > E-Mail: slein@wrc.xerox.com > > Phone: (716) 422-5169 > > Fax: (716) 265-7133 > > > > Xerox Corporation > > Mail Stop 105-50C > > 800 Phillips Road > > Webster, NY 14580 > > > > > >
Received on Tuesday, 5 August 1997 04:33:40 UTC