Make worksheet auto-sync and collaborative editing smarter and more granular

[qed777]

We ought to make collaborative worksheet editing somewhat more intuitive, even if we stop short (for now) of implementing full-strength operational transformations or employing the Wave Federation Protocol.

See sage-notebook.

From this comment at #7254:

 The browser and server do not update their `state_number`s if a new cell is added at the end of a sheet, when text cells are added, or cells are deleted. Should we add these to the list, along with the `'delete_all_output'`, `'pretty_print'`, `'system'` worksheet commands? 

CC: @jasongrout @haraldschilly

Component: notebook

Issue created by migration from https://trac.sagemath.org/ticket/7362

[qed777]

comment:1

See this sage-notebook thread, too.

[qed777]

comment:2

Replying to @qed777:

See this sage-notebook thread, too.

The links:

• MobWrite - theory, client setup, server setup, status.
• Cola - Real-time shared editing in Eclipse - screencast.

MobWrite seems to be a good option, provided it doesn't overload client and server. We can call mobwrite.share for new input cells and mobwrite.unshare for deleted cells. If MobWrite cannot synchronize arbitrary HTML, perhaps we can mobwrite.share a hidden auxiliary cell that holds the escaped HTML of its corresponding output cell. We can update the output cell's innerHTML when MobWrite triggers the auxiliary's onchange handler. Of course, this assumes that we don't run more than one synchronization algorithm at a time.

[boothby]

comment:3

Closing deprecated notebook tickets