Lifespan shorter than the deadline period
Rule 7 · applies to the subscriber · Back to all rules
Breaks a guarantee. Samples can expire before the deadline window closes, so the reader reports missed deadlines even when the writer published on time.
If you set Lifespan duration L together with Deadline period longer than L
Breaks a guarantee
Example
Lifespan 50 ms with a 100 ms deadline. Every sample expires before the next deadline check, producing constant requested-deadline-missed events.
How to fix it
Set Lifespan at least as long as the Deadline period.
Why this rule is flagged
What the DDS specification says
The DDS specification does not settle this case on its own, so the rule rests on direct measurement.
What the engine source code shows
The behavior here does not depend on a specific engine's implementation, so the rule follows from the measurements.
What the measurements show
| Item | Value |
|---|---|
| Dataset | Download CSV |
| Fixed QoS setting | None |
| Tested variable | LIFESPAN.duration, DEADLINE.period |
| Tested values | LIFESPAN.duration ∈ {100 ms, 200 ms, 400 ms}, DEADLINE.period ∈ {150 ms, 300 ms, 500 ms} |
| Rule-relevant case | LIFESPAN.duration < DEADLINE.period |
| Tested engines / versions | Fast DDS 2.14.6 (Jazzy), Cyclone DDS 0.10.5 |
| Network setting | RTT = 1 ms, loss ∈ {0%, 20%}, PP = 20 ms, message size = 1024 B |
Measurement result
The heatmaps show average delivery ratio across tested lifespan and deadline settings.