Resources
Usage
Recommended
qos_profile_sensor_data: use if you don’t care about dropping the odd message (best effort)
qos_profile_services_default: use for services when you care about getting your responses (reliable)
qos_profile_parameters / qos_profile_parameters_events / qos_profile_action_status_default: unknown, haven’t tried these yet, but presumably suit most cases
Latched Topics
Nothing exists out of the box, you’ll want to set up something like:
def qos_profile_latched():
return rclpy.qos.QoSProfile(
history=rclpy.qos.QoSHistoryPolicy.RMW_QOS_POLICY_HISTORY_KEEP_LAST,
depth=1,
durability=rclpy.qos.QoSDurabilityPolicy.RMW_QOS_POLICY_DURABILITY_TRANSIENT_LOCAL,
reliability=rclpy.qos.QoSReliabilityPolicy.RMW_QOS_POLICY_RELIABILITY_RELIABLE
)
Do not Use
qos_profile_default: this one exists in rclcpp, but it is recommended not to use it, one should think more deeply about the profile being set (see rclpy/qos.py#L33 where they mention exactly this and intentionally hide the default).
qos_profile_system_default: use the underlying dds implementation’s default