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
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