[Standards] Whiteboard XEP, Gajim and GSoC2008

Joonas Govenius joonas.govenius at gmail.com
Fri Mar 7 03:58:37 UTC 2008

> On 3/3/08 6:23 PM, "Joonas Govenius" <joonas.govenius at gmail.com> wrote:
>     >  What I don't like of the current SXE definition is the inability of
>     >  sending the whole document or chunks it, instead of being obliged of
>     >  sending all the necessary events for recreating the document.
>     If the extra bandwidth really is such a problem we could define an
>     implicit way of creating the objects out of a chunk of XML as I've
>     mentioned but it doesn't seem worthwhile to me at this point.
Boyd Fletcher wrote:
> sending the entire document is a big show stopper for large group 
> collaboration (especially if you are using a large number of 
> whiteboard pages) and if your are using satellite/cellular 
> communications (like is very common in military or 3rd world countries).
> we dealt with the problem by using sequence numbers and the client can 
> request which numbers it wants to receive.

You and Fabio are referring to slightly different issues here:

1. Fabio is concerned about the bandwidth used for sending the state to 
a client when it first joins the session. It would be higher by some 
significant constant factor so this is probably a legitimate concern but 
could be solved as I mentioned above; I just think it would be a little 
premature at this point.

2. You are concerned about optimizing reconnects by taking advantage of 
the state that the client already has. I gave this some thought and 
there's actually no reason why SXE couldn't do basically the same thing 
as your protocol:

The client that reconnects would send a "last-received-sender", 
"last-received-id", and "last-sent-id" that identify the last <sxe/> 
element that it received and the last <sxe/> element that it sent.

Assuming that that "last-sent" element came through, the joiner would 
then only receive edits sent by others after the "last-received" element.

Only the server-side reflector (or bot) would be required to accommodate 
these requests though because the clients aren't required to remember 
details about who sent which edits.


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