[Babel-users] babel topologie

Juliusz Chroboczek Juliusz.Chroboczek at pps.jussieu.fr
Wed Dec 23 13:08:31 UTC 2009


>> A already connected to the socket for the frontend, but afaik i
>> gives me just one worldview.

> Because babel itself does not know the complete topology.

More precisely, every Babel node knows which are its neighbours.  It
cannot distinguish between a second order and a third order neighbour --
it only knows that its reachable.

This is not a bug, it's a feature.  It implies that a minor change in
the topology doesn't need to be broadcast throughout the network, it's
only sent to the immediate neighbourship.

> Theoritically, you could, however, build some piece of software which
> would:

[iteratively construct the neighbourship graph]

> I have no idea how hard it would be, let alone if this is possible at
> all (is there enough information to aggregate things?).

Yes, there is, every node has a unique node-id.  However, an iterative
algorithm would probably be overly racy.

What I have considered doing at some point (when we get around to
rewriting BabelDraw) would be to have the controller simultaneously
connected to multiple Babel nodes, and build as much of the topology as
it can get from those nodes.

                                        Juliusz



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