Jochen's call, and the right one: a module cannot choose a port well,
because it is written once and assigned anywhere. Any number it picks is
a guess about a machine it has never seen, and two modules guessing the
same number is not a mistake either of them made.
Writing it up turned up something the issue had missed. The same number
appears three times in every module — the rule set, what a consumer is
told, and what the runtime publishes — and nothing checks that they
agree. They agree today because one person wrote all three. A module
whose `serves` said one thing and whose container published another
would resolve, compose, apply, and hand every consumer a port that
answers nothing.
So the decision is one source with the other two derived, and an
assignment made once and kept, as a credential is.
The part that needed thought is ports that cannot move — mail on 25,
submission on 587. Those become claims, which is what the mesh already
has for what is singular on a machine. Two modules wanting 25 is the
same shape as two wanting the seat, and gets refused by name at
assignment rather than by a container runtime at apply. That makes this
mostly a matter of pointing an existing mechanism at ports.
Left open: whether a module should publish to the machine at all.
Assignment makes publishing safe without making it necessary.
jschoubben
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