SubscribeFrame
dataclass #
SubscribeFrame(subscription_id, session_id=None, task_id=None, event_types=None, since_envelope_id=None)
client → hub: open a push subscription on a session or task.
At least one of session_id / task_id must be set. since_envelope_id is the cursor for at-least-once replay over a reconnecting transport; in-process delivery is exactly-once by per-session lock.