Add a comment describing durability.

Signed-off-by: Chris Lalancette <clalancette@osrfoundation.org>
ros2 · Jan 11, 2017 · fedd9d9 · fedd9d9
1 parent df7827e
commit fedd9d9
Showing 1 changed file with 4 additions and 0 deletions.
diff --git a/image_tools_py/src/image_qos_profile.py b/image_tools_py/src/image_qos_profile.py
@@ -46,6 +46,10 @@ def create_qos_profile(depth, reliability_policy, keep):
     else:
         raise ValueError("Invalid keep policy (must be 0 for keep last or 1 for keep all")
 
+    # The durability policy determines what happens to samples that were sent before
+    # a subscribe joined the network.
+    # VOLATILE - Past samples ignored
+    # TRANSIENT_LOCAL - Past samples are sent to the subscriber
     qos_profile.durability = QoSDurabilityPolicy.RMW_QOS_POLICY_DURABILITY_VOLATILE
 
     return qos_profile