DDS

DDS content filter parameter substitution (%0, %1) silently fails for string fields in ROS 2 with Fast DDS. The root cause is three layers deep — the DDS SQL grammar requires quoted string literals, but no ROS 2 layer adds the quotes. Here’s how I traced it and where to fix it.

A detailed technical account of running px4-ros2-interface-lib integration tests against PX4 SITL — from discovering that the project’s CI never runs them, through three different simulator backends, five distinct failure modes, and the surprising DDS payload mismatch that blocked everything. Every dead end documented.