Step 3.4. On the new bus there is no reply queue to declare and no
correlation to check: each account is granted one inbox prefix and no
other, so an answer cannot reach the wrong asker. That settles a cost
build.go records having paid — on a shared reply exchange every asker saw
every result, which is why the correlation was checked rather than assumed.
And a tool nobody serves says so at once rather than after the whole wait.
The difference between "that module is down" and "that tool is slow" is the
first thing a person asking wants, and both tests are against a real server
because both are claims about what the server does, not about this code.
RequestBuild stays as it is, and is a different shape on the new bus rather
than the same one: a build takes minutes, so it is work submitted to a
queue with the outcome returning to a reply subject the request carries —
the pattern design 25 §2 already sets for anything crossing a stream. It
touches the builder too, so it goes with that conversion.
Comments framed the new bus by what it replaces — a comparison in almost
every explanation, which reads as though NATS were a variant of the old
thing rather than the mesh's nervous system. Removed throughout, and
OverAMQP becomes OverCurrent: the seam's two sides are the bus the mesh
runs on today and the one being built, not two protocols.
What remains is the client library's own package name, which is its name.
Step 3.4, first half. Every one of these took an *amqp.Channel, so the
transport reached every caller and swapping it meant touching all of them.
The seam turned out to be small — the controller sends exactly two kinds of
message that expect no answer — which is the same measurement that said
this bus could be replaced at all.
Bus is stated in the mesh's words, not a transport's: PublishEvent and
PublishDeclaration. Two implementations, both shipping, because steps 1 to
4 leave every node on AMQP and the NATS one is selected at the rollout.
Both ship is also what makes them comparable: one conformance fixture holds
both to the same envelope, and the NATS one is checked against a real
server reading back from the stream rather than from the code that wrote it.
Still on *amqp.Channel: RequestBuild and Ask, which carry reply-queue
machinery, and the whole consume side — the control loop, enrolment, serve.
jschoubben