A protocol's lifecycle produces two categories of events. What are they, and how is each delivered?

Protocol state changes are pushed out as Server-Sent Events (SSE); user-defined notifications are published through an AMQP message broker.

* Two lanes out (SSE for state changes, AMQP for notifications after commit); one lane back in (REST + short-lived JWT). *

NPL splits everything a running protocol emits into two streams:

1. Protocol state changes → Server-Sent Events (SSE) — a lightweight one-way HTTP push from server to client. When a protocol's state changes, an SSE is emitted; consumers subscribe to update a user interface or notify external systems in real time.
2. User-defined notifications → AMQP message broker — custom, typed messages the developer explicitly declares and fires from within the NPL logic, delivered through a message broker (AMQP = Advanced Message Queuing Protocol).

The split matters: state changes are automatic and structural, while notifications are hand-authored integration points the developer designs for specific consumers.

Go deeper:

• Server-sent events (Wikipedia) — the one-way HTTP push (text/event-stream) used for the automatic state-change lane.
• Advanced Message Queuing Protocol (Wikipedia) — the open broker protocol carrying the user-defined notification lane.