From: Thomas Lord <lord@emf.net>
To: Brian Templeton <bpt@tunes.org>
Cc: emacs-devel@gnu.org
Subject: Re: GSoC: collaborative editing
Date: Mon, 13 Apr 2009 22:24:30 -0700 [thread overview]
Message-ID: <1239686670.6492.240.camel@dell-desktop.example.com> (raw)
In-Reply-To: <87zlejdhqn.fsf@tunes.org>
On Mon, 2009-04-13 at 23:41 -0400, Brian Templeton wrote:
> Thomas Lord <lord@emf.net> writes:
>
> > On Mon, 2009-04-13 at 18:04 -0400, Brian Templeton wrote:
> >> Thomas Lord <lord@emf.net> writes:
> [...]
> >> > There is a second question. What payload goes
> >> > in chat messages? How are mutually remote buffers
> >> > synchronized. In that area I suggest:
> >> >
> >> > 1. Carefully evaluating and considering adopting
> >> > (and helping to adapt) the "mobwrite"
> >> > system of "diff sync" (see
> >> > http://code.google.com/p/google-mobwrite/
> >> > )
> >> >
> >> I am planning to use operation transformation, which is also used by
> >> most existing collaborative editors (Gobby, SubEthaEdit, etc.).
> >> Operation transformation is easier to implement and more elegant than
> >> differential synchronization, IMO. In the context of real-time
> >> collaborative editing of text documents, DS does not seem to solve any
> >> actual problems that aren't already solved by OT.
> >
> > Does "operation transformation" mean taking a
> > log of edit commands and applying outcome-preserving
> > transformations upon it to compress it to a shorter
> > log of edit commands?
> >
> > If so, fwiw, from my background -- that *does* sound like
> > a much better approach. I could boor you for hours as to
> > why but ... well, why? No need. :-)
>
> Operation transformation does use outcome-preserving transformations,
> not for compressing the log of edit commands but to reconcile the
> effects of concurrently generated commands.
Oh, well. It will eventually do both.
> My implementation will only require an inclusion transformation, which
> transforms an operation to "include" the effect of another operation,
> which allows one to avoid divergence of document state when edits are
> being applied concurrently. (For example, if Bob inserts a character at
> position 12 at the same time that Alice inserts five characters at
> position 0, Alice needs to shift the position of the insertion operation
> she recieves from Bob forward by five characters to take into account
> her own operation that Bob didn't know about.)
Sure. I think OT and diff sync mostly turn out
the same except that diff sync synthesizes a
fake edit stream from the buffer rather than
capturing the actual edit stream.
> [...]
> > It's a big topic, though, so it would help if I
> > were more certain you meant by "OT" what I take
> > you to mean. Can you point to some docs I can
> > read to make sure we're talking about the same thing?
>
> You can get a decent overview from the ACE project's evaluation of
> various algorithms:
>
> <http://ace.svn.sourceforge.net/viewvc/ace/ace/tags/ACE_20050624/doc/pdf/algorithm.pdf>
>
> The Jupiter algorithm is described in this paper, also linked to in my
> initial post:
>
> <ftp://ftp.lambda.moo.mud.org/pub/MOO/papers/JupiterWin.ps>
>
> An inclusion transformation function for operations on text documents is
> defined in this paper:
>
> <http://www.cs.cityu.edu.hk/~jia/research/reduce98.pdf>
>
>
Thanks.
-t
next prev parent reply other threads:[~2009-04-14 5:24 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-04-11 20:07 GSoC: collaborative editing Brian Templeton
2009-04-12 18:02 ` Michael Albinus
2009-04-13 1:22 ` Miles Bader
2009-04-13 9:08 ` Michael Albinus
2009-04-13 14:43 ` Thien-Thi Nguyen
2009-04-13 16:11 ` Thomas Lord
2009-04-13 22:04 ` Brian Templeton
2009-04-13 22:49 ` Thomas Lord
2009-04-14 3:41 ` Brian Templeton
2009-04-14 5:24 ` Thomas Lord [this message]
2009-04-13 22:52 ` Thomas Lord
2009-04-14 10:42 ` Thien-Thi Nguyen
2009-04-15 2:03 ` Thomas Lord
2009-04-13 17:44 ` Stefan Monnier
2009-04-13 23:10 ` Richard M Stallman
2009-04-13 23:32 ` Brian Templeton
2009-04-14 3:01 ` Stephen J. Turnbull
2009-04-14 4:02 ` Brian Templeton
2009-04-14 7:29 ` Stephen J. Turnbull
2009-04-14 9:09 ` Brian Templeton
2009-04-15 2:02 ` Thomas Lord
2009-04-14 21:14 ` Richard M Stallman
2009-04-15 2:18 ` Thomas Lord
2009-04-15 1:19 ` Brian Templeton
2009-04-15 1:27 ` Brian Templeton
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