[ros-users] [Discourse.ros.org] [Next Generation ROS] Custom RMW layer not recognized

[Louis Mayencourt]

Hi, 

I'm trying to implement a new RMW. I successfully created a packages with the following structure but ament don't recognise it as a rmw implementation. 
```
    rmw_tinq
    |-- rmw_tinq_cpp
      |-- CMakeLists.txt
      |-- packages.xml
      |-- src
          |-- functions.cpp
```

My CMakeList.txt have I think all the required dependencies:
```
 find_package(rmw REQUIRED)
    find_package(rosidl_generator_c REQUIRED)
    find_package(rosidl_generator_cpp REQUIRED)
    find_package(rosidl_typesupport_introspection_c REQUIRED)
    find_package(rosidl_typesupport_introspection_cpp REQUIRED)
    ...
    configure_rmw_library(rmw_tinq_cpp)
    ....
    register_rmw_implementation(
      "c:rosidl_typesupport_c:rosidl_typesupport_introspection_c"
      "cpp:rosidl_typesupport_cpp:rosidl_typesupport_introspection_cpp")
```
and same for my package.xml : 
```
    <build_depend>rmw</build_depend>
    <build_depend>rosidl_generator_c</build_depend>
    <build_depend>rosidl_generator_cpp</build_depend>
    <build_depend>rosidl_generator_dds_idl</build_depend>
    <build_depend>rosidl_typesupport_introspection_c</build_depend>
    <build_depend>rosidl_typesupport_introspection_cpp</build_depend>

    <build_export_depend>rcutils</build_export_depend>
    <build_export_depend>rmw</build_export_depend>
    <build_export_depend>rosidl_generator_c</build_export_depend>
    <build_export_depend>rosidl_generator_cpp</build_export_depend>
    <build_export_depend>rosidl_typesupport_introspection_c</build_export_depend>
    <build_export_depend>rosidl_typesupport_introspection_cpp</build_export_depend>
```
But when I try to build with ament, my rmw package is build after rmw_implementation, and rmw_implementation failed : 

    CMake Error at /data/loumay01/cortex_M/ros2/install/share/rmw_implementation_cmake/cmake/get_default_rmw_implementation.cmake:62 (message):
      Could not find ROS middleware implementation 'NOTFOUND'.  Choose one of the
      following:
    Call Stack (most recent call first):
    CMakeLists.txt:28 (get_default_rmw_implementation)

Any ideas on what is missing here ?





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