Surely they are. Without intention preservation, OT is quite useless. It is pretty easy to define an transform that provides consistency but does not preserve intention. For example, the transform could map any input to an empty document! However, that is probably not what the user intended, especially if they were, say, inserting characters into a text document.
Dan On Dec 1, 5:01 pm, Brett Morgan <[email protected]> wrote: > Dan, > > Does this mean that the wave servers are doing intention preserving in their > OT implementation? I haven't seen where that is implemented in the FedOne > released code base... > > brett > > > > > > On Tue, Dec 1, 2009 at 4:41 PM, Daniel Paull <[email protected]> wrote: > > > A small correction. I said, "all sites will agree that the result is > > either "16" or that the result is "17", regardless of the order in > > which they apply the operations." > > > I should have said that all sites will agree that the result is > > either "167" or that the result is "176", regardless of the order in > > which they apply the operations. > > > Note - I have assumed that each client deleted and inserted only one > > character. > > > Dan > > > Daniel Paull wrote: > > > Hi Jelke, > > > > I assume you mean that the operations by the two clients are performed > > > concurrently. You are right in your thinking that the transformation > > > is ambiguous - this is where OT starts to get tricky! > > > > Please refer the OT Functions section of the OT page on Wikipedia: > > > > http://en.wikipedia.org/wiki/Operational_transformation#OT_Functions > > > > which I will repoduce below: > > > > T(ins(p1,c1,sid1),ins(p2,c2,sid2)) :- > > > if (p1 < p2) return ins(p1,c1,sid1) > > > else if (p1 = p2 and sid1 < sid2) return ins(p1,c1,sid1) > > > else return ins(p1 + 1,c1,sid1) > > > > Notice that when the insertion positions of two concurrent insert > > > operations are equal (ie, when p1 = p2), the function resorts to > > > comparing site identifiers, sid1 and sid2. It is required that site > > > identifiers are globally unique and have a total ordering. Now the OT > > > function is unambiguous and all sited will agree that the result is > > > either "16" or that the result is "17", regardless of the order in > > > which they apply the operations. > > > > Now, I'm not sure exactly what Wave does regarding site identifiers, > > > but I am sure that the above strategy will be used. > > > > Cheers, > > > > Dan > > > > On Nov 29, 10:05 pm, "Jelke J. van Hoorn" <[email protected]> wrote: > > > > Hi, > > > > > I was looking the "under the hood" vidieo of Google IO 2009. And I'm > > > > wondering what happens in the following situation: > > > > > On the server a piece of text is lets say "15" and two clients alter > > > > the same piece in "16" and "17" respectively. > > > > What would be the outcome of the transforms? There is no unambigeous > > > > way to cope with this edit I think. > > > > > Grtz Jelke > > > -- > > > You received this message because you are subscribed to the Google Groups > > "Wave Protocol" group. > > To post to this group, send email to [email protected]. > > To unsubscribe from this group, send email to > > [email protected]<wave-protocol%2bunsubscr...@goog > > legroups.com> > > . > > For more options, visit this group at > >http://groups.google.com/group/wave-protocol?hl=en. > > -- > Brett Morganhttp://domesticmouse.livejournal.com/ -- You received this message because you are subscribed to the Google Groups "Wave Protocol" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/wave-protocol?hl=en.
