The circuit provides two special element types
called subscriptions. Their job is to notify you when new
circuit servers join the systems or others leave it.
Both of them behave like receive-only channels.
circuit mk@join /X88550014d4c82e4d/watch/join circuit mk@leave /X88550014d4c82e4d/watch/leave
The join subscription delivers a new message each time a cicruit server joins the system. The received message holds the anchor path of the new server.
circuit recv /X88550014d4c82e4d/watch/join
Similarly, the leave subscription delivers a new message each time a circuit server disappears from the system.
circuit peek /X88550014d4c82e4d/watch/join