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I am researching collaborative editing systems for some work, but so far my search is turning up blank.

Collaborative real-time editing systems almost all have features like:

  • Many users can edit the document at the same time
  • All changes are dated and saved in a linear revision history
  • Edits are visible in semi-real time
  • Who-wrote-what is tracked for all content

I cannot think of a data- and procedure model to encompass all of these without huge inefficiencies, for example:

  • Take user input as a few typestrokes at a time, thus enabling real-time visibility but with horrible server loads.
  • Take user input as element changes, thus disabling real-time visibility and complicating many-user-editing of one paragraph.
  • Edit a XML Document Model Object in place responding to inputs, but making it difficult to version/revision track.
  • Edit linear text stored in an appropriate editing structure responding to inputs, making it difficult to verify that correct markup is being generated.
  • Store revision history accumulating, requiring computational resources but easing on space.
  • Store revision history whole, requiring space but easing on computation.

Am I off track? Does there exist good solutions to these problems? What, if any, is the relevant litterature?

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Are you interested in developing such a system, or do you ask if a system that provides this functionality is known? – A.Schulz Jan 15 '13 at 13:59
Have you looked into existing collarborative editors? – Raphael Jan 15 '13 at 14:13
@A.Schulz I am interested in ultimately developing such a system tailored to a specific purpose, but right now is Research only. – Karl Damgaard Asmussen Jan 16 '13 at 10:33
@Raphael I am investigating Etherpad, but if I am not mistaken, there isn't a lot of open-source systems of this kind. – Karl Damgaard Asmussen Jan 16 '13 at 10:34
I have used Gobby myself, which is open source. There seem to be about handful of open-source collaborative editors, including Etherpad. – Raphael Jan 16 '13 at 11:18

The usual approach is operational transformation. The wikipedia page seems to be pretty good. Here are some other references:

Here's a paper on a different approach: Real time group editors without operational transformation. (Note: I haven't actually read it, so can't speak to how good it is)

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Thank you so much! This was the magical keyword I lacked. – Karl Damgaard Asmussen Jan 21 '13 at 9:02

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