ROS2 QoS Calculator

Set a publisher and subscription QoS profile and see whether they'll actually connect. The compatibility rules here mirror rmw_dds_common::qos_profile_check_compatible policy-for-policy, so the verdict matches what ROS2 itself would report.

Publisher

ReliabilityDurabilityHistoryDepth

Subscription

ReliabilityDurabilityHistoryDepth

Compatibility

Compatible — this publisher and subscription will connect.

✓

Reliability

Compatible.

✓

Durability

Compatible.

✓

Deadline

Compatible.

✓

Liveliness

Compatible.

✓

Liveliness lease duration

Compatible.

How QoS matching works

A subscription requests a QoS policy and a publisher offers one. They can connect only if the publisher's offer is at least as strict as what the subscription requires — e.g. a subscription requesting Reliable needs a Reliable publisher (a Best Effort publisher won't satisfy it), but a subscription requesting Best Effort is happy with either.

History (Keep Last / Keep All) and Lifespan only affect local buffering and message expiry — they never block a connection, which is why they're not part of the compatibility check above.