pub const STARTUP_MARKER_PARAM: &'static str;Expand description
Reserved MetadataParameters key marking a message as a startup
route-probe marker rather than node data.
The zenoh data plane is direct node-to-node pub/sub, so a producer that
publishes before a consumer’s subscription has propagated would drop those
early samples. Rather than infer route-readiness from zenoh declarations,
each producer publishes markers on its real output topic while an output is
still on the reliable daemon path, and each consumer answers every received
marker with an ack (see STARTUP_ACK_PARAM): an ack arriving back at the
producer is end-to-end proof that the route pair carries data. The producer
stops marking an output — and switches it to the direct zenoh path — once
all its required consumers have acked, but only within a bounded startup
window: an output still un-acked when the window closes is pinned to the
daemon path for the rest of the run, so a topic’s messages never straddle a
path switch (dora-rs/dora#2891). A route that never proves itself just keeps
the output on the daemon path.
The __dora_ prefix is reserved; user parameters must not use it. Receivers
filter markers before decoding the payload, so they never reach user code.