I have been mulling over the notion of setting up the Slonik STORE
LISTEN(ORIGIN=a, RECEIVER=b, PROVIDER=c) configuration.

The "features" of this idea:

This involves having a table (view?) containing the intended parentage
for each node, that is, which nodes point to which parents.

This would allow the following good things:

- Can't drop a node that has children, probably with other possible data
checks

- Can calculate the full "listener matrix" within pl/pgsql instead of
doing it in Perl (take a look at init_cluster.pl, subroutine
generate_listen_paths()).

My preliminary thinking about it was pointing to there being a pretty
elegant way to do this using SQL queries that might be more readable
than the dynamic programming formulation embedded in that subroutine.
(I didn't write out the Bellman equations, but took a look back at my
old optimization texts ;-).)

The primary problem that this solves is to create those STORE LISTEN()
definitions, which get pretty involved to generate by hand if you get
more than three nodes.

In doing some further thinking, I noticed a couple of conspicuous
challenges:

1. There can be no fixed association with sets, as the sl_listen table
does not contain set fields, and different sets can use differently
shaped subscription trees.

(I think users would be doing something pretty stupid to have _wildly_
different arrangements for different sets, but I still have to support
it...)

2. The tree cannot be based on subscriptions because it needs to exist
before any subscriptions are established

In effect, I have no fixed place where I can get the information at
the point at which I most need it.

Once all nodes are subscribed, I could use subscription information to
weight the cost functions, but I need the data BEFORE we do anything.

I'm going to drop some notes into the ToDo file, and leave it for now.

- Maybe a better "seeding" idea will emerge later.

- An idle thought: Maybe we do some manifest "defaulting."
   - In the beginning, all listens go to node #1
   - Every time a subscription is established, the listeners
     get reevaluated based on what subscriptions exist.
  The idea's not dead; just dormant...
-- 
(reverse (concatenate 'string "ofni.sailifa.ac" "@" "enworbbc"))
<http://dev6.int.libertyrms.com/>
Christopher Browne
(416) 673-4124 (land)