correct name of shared libraries and their location (#722) (#726)

* correct name of shared libraries and their location



* add instruction for running dlopen_composition in separate sections of Linux and windows



* format the composition Documentation



---------


(cherry picked from commit c3a5fdf)

Signed-off-by: Aniket Kumar Roy <aniketroy769@gmail.com>
Co-authored-by: Aniket Kumar Roy <aniketroy769@gmail.com>

Author: mergify[bot]

composition/README.md

@@ -35,12 +35,53 @@ ros2 run composition manual_composition
 
 This runs `dlopen_composition` which is an alternative to run-time composition by creating a generic container process and explicitly passing the libraries to load without using ROS interfaces.
 
+First run the command to find the libraries prefix path.
+
+```bash
+ros2 pkg prefix composition
+```
+
+Then you can find the prefix path of the required shared libraries to load.
+
 The process will open each library and create one instance of each “rclcpp::Node” class in the library.
 
+```bash
+ros2 run composition dlopen_composition <path_to_talker_component_shared_library> <path_to_listener_component_shared_library>
+```
+
+#### Linux
+
+The libraries will be present in `<prefix_path>/lib/` as `lib*.so` files.
+
+Run the following command to load the libraries.
+
 ```bash
 ros2 run composition dlopen_composition `ros2 pkg prefix composition`/lib/libtalker_component.so `ros2 pkg prefix composition`/lib/liblistener_component.so
 ```
 
+#### Windows
+
+On Windows, we will need the `*.dll` files.
+Since command substitution will not work on Windows, you have to give the absolute path of the libraries.
+
+The libraries will be in `<path_to_your_ros2_installation>\bin\`, so we have to run.
+
+```bash
+ros2 run composition dlopen_composition <prefix_path>\bin\talker_component.dll <prefix_path>\bin\listener_component.dll
+```
+
+To get the `prefix_path` run
+
+```bash
+ros2 pkg prefix composition
+```
+
+For example if our `prefix_path` comes out to be `C:\pixi_ws\ros2-windows\` we will run
+
+```bash
+ros2 run composition dlopen_composition C:\pixi_ws\ros2-windows\bin\talker_component.dll C:\pixi_ws\ros2-windows\bin\listener_component.dll
+```
+
 ### Linktime Composition
 
 Similar to previous, this runs `linktime_composition` which **links all classes from libraries** that are registered under the **library_path** with the **linker**.