On Jan 29, 9:36 pm, Torben Weis <[email protected]> wrote:
>
> Wave's OT cannot handle such a scenario. There are peer-to-peer OT concepts
> which can deal with it, but wave does not currently.
>

Torben - I'm building a lot of respect for you based on many of your
posts lately.  This comment is spot on!

The Wave OT implementation avoids satisfying TP2 by forcing a strict
client/server topology.  This is, of course, borrowed from the Jupiter
system.  As soon as you try to elect a new master server, you are in
for a world of pain in trying to get clients to connect to the new
server without rolling back (and hence losing edits that the user
performed) - what happens to operations that were "in fight", but not
delivered?  What acknowledgements had been sent from the server?  What
happens to clients that received a server acknowledgement, but the new
master server is unaware that it had been sent?  What order had the
old server applied operations in?  So many questions...  Of course,
the correct answer to them all is to implement an OT system that
satisfies TP2.

If TP2 is satisfied, the concept of a "master server" does not exist
as a fundamental concept.  You may choose to have some node in the
network act as a point of presence for clients to connect to, and this
node may promise to persist and protect waves, but this is merely a
configuration choice.

If TP2 is satisfied, the concept "server clustering" is trivial - just
add more peers into the network that replicate waves and accept
connections from clients.  Implementing a server cluster with the
current OT algorithms must be fraught with danger...  Personally I
don't see how it could be done without putting massive constraints on
the cluster, such as "all clients for wave X must form socket
connections to server Y in the cluster". (BTW - I read that constraint
as "Cluster?  What cluster??")

While TP2 is unsatisfied, so am I.


Cheers,

Dan


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