Message-ID: <4FD6422BE942D111908D00805F3158DF0A757934@RED-MSG-52> From: Chris Kaler <firstname.lastname@example.org> To: "'Geoffrey M. Clemm'" <email@example.com>, Date: Mon, 30 Nov 1998 11:39:39 -0800 Subject: RE: checkout/checkin/uncheckout vs. lock/unlock What we agreed to was that we liked multiple methods instead of just one :-). However, we discovered that there was a conflict between checkout and lock. I was supposed to start an email thread about it, but got hung up. My idea was that if we make them the same method, you remove much of the confusion. A checkout is, in many ways, a lock. You "checkout" either shared or exclusive. That is the same as a lock. The only difference is that you have a working resource. - What if you want to leave the working resource available for anyone to modify? In what sense have you created a lock? You make it shared and everything is fine - When you checkin a resource, you have now made an immutable revision. In what sense have you "unlocked" anything? I argue that a checkout is an implicit lock against the resource and by checking in, you have removed that lock. - Converely, when you "uncheckout" a working resource, you delete it. In what sense have you "locked" anything? This is another reason why I like the LOCK method. In many systems, explicit locking is used. PUTs with require the lock-id to be specified. By tieing the two together, clients don't need to worry (or think) abou the "working resource". They do their PUT to the versioned resource and specify the checkout lock. The server validates the lock and updates the working resource. I actually think this is much easier for the client than having to track the versioned resource, the working resource, and the lock-id. Less information, consistent protocol. - When you "checkout" a versioned resource, you create a new (working) resource. A "lock" is not something you expect to create a new resource. But many (most) checkouts result in the versioned resource being locked in some way. So this approach lessens the round-trips and the information the client must track and keeps the protocol almost exactly the same as non-versioning. Chris -----Original Message----- From: Geoffrey M. Clemm [mailto:firstname.lastname@example.org] Sent: Tuesday, November 03, 1998 10:30 AM To: email@example.com Subject: checkout/checkin/uncheckout vs. lock/unlock Why was the checkout/checkin/uncheckout functionality assigned to the lock/unlock methods? As I recall, in our last meeting, we agreed (or at least, all of us but Chris agreed, and Chris reluctantly accepted :-) that they each really needed to be a separate method. There was a proposal to allow you to optionally "lock" a working resource as part of the checkout command (which is fine with me), but making the checkout command actually be a variant of the "lock" makes no sense to me. - What if you want to leave the working resource available for anyone to modify? In what sense have you created a lock? - When you checkin a resource, you have now made an immutable revision. In what sense have you "unlocked" anything? - Converely, when you "uncheckout" a working resource, you delete it. In what sense have you "locked" anything? - When you "checkout" a versioned resource, you create a new (working) resource. A "lock" is not something you expect to create a new resource. So I propose that we not overload lock/unlock, but that we have 3 new methods: CHECKIN, CHECKOUT, UNCHECKOUT. Cheers, Geoff Note: my previous message to firstname.lastname@example.org appears to have been distributed fine (or at least, it make it back to me with no trouble. So whatever problem Chris was having seems to have either been fixed, or is a local problem at his home mailing site.