[Spread-users] Workshop Notes

Ben Laurie ben at algroup.co.uk
Fri Aug 3 05:32:45 EDT 2001

At the Spread workshop recently, I made a number of notes of things that
(I thought) we generally agreed would be good things to do. As promised,
here they are:

Multiple tokens to allow bursty nodes to send sooner in large networks -
the idea was that if more than one token circulated, then a node that
has bursts of traffic can send their traffic sooner. I forget the exact
mechanics of how ordering continues to work in this case, but I believe
it wasn't considered impossible.

Nodes that are shutting down deliberately should announce that they are,
to avoid the cost of a token timeout.

Instead of sockets, shared memory could be used between the clients and
the daemon.

Release an implementation of a general-purpose correct state machine for
the "red yellow green" algorithm.

Add an "even safer than safe" mode, where the application acknowledges
that the message has been processed.

(This one was out of band, so some people may be unaware of it) I
suggested to Jonathon that it should be possible to calculate an optimal
hierarchy of nodes under some assumptions (e.g. all nodes/networks are
equal), where "optimal" means "minimises latency" or "maximises
throughput" (or maximises some other quantity). The idea being that you
can exploit the different properties of Ring and Hop to improve

Check that all participating nodes are configured identically. Refuse to
join a ring where this is not true.

In Hop, aggregate headers of messages that aren't sent to all sites
(assuming that isn't already done).

Read failures shouldn't close the fd - SP_disconnect should be called
after the application has fielded the error (this is required for
correctness in threaded programs).

Add a void * to the session so auth module can share data with access
control module (in the daemon).

And finally, a discussion point: should there be a standard way to load
multiple access control modules?





"There is no limit to what a man can do or how far he can go if he
doesn't mind who gets the credit." - Robert Woodruff

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