General information about this repository, including legal information, build instructions and known issues/limitations, are given in README.md in the repository root.

The rclc_examples package

The rclc_examples package provides examples for using the RCLC-Exector and convenience functions.

• example_executor.c provides the example for the RCLC-Executor. It creates one publisher and one subscriber and configures the RCLC-Executor accordingly. Then the spin_some() function is demonstrated.
• example_executor_convenience.c provides the example for the RCLC-Executor with the convenience functions from rclc. It creates one publisher and one subscriber and configures the RCLC-Executor accordingly. Then the spin_some() function is demonstrated.
• example_executor_trigger.c demonstrates the trigger condition of the RCLC-Executor.
• example_service_node.c implements a service node with the RCLC-Executor.
• example_client_node.c implements a client node with RCLC-Executor.

The reduction of code lines for configuring the necessary RCL objects for RCLC-Executor directly with RCL objects compared to using the convenience functions is about 24%:

• example_executor.c: 92 LoC (lines 56-148)
• example_executor_convenience.c: 70 LoC (line 17 + lines 57-126)

counting only the lines of code in which the RCL objects are defined).

Example RCLC-Executor using RCL objects directly

Step 1 Setup ROS 2 Workspace

Open a terminal with ROS 2 workspace. Assuming that the ROS 2 installation resides in /opt/ros/ROSDISTRO, setup the ROS2 environment by:

~$ source /opt/ros/$ROSDISTRO/setup.bash

Step 2 Build the package Download and build the the packages rclc and rclc_examples in a workspace (for example ros2_ws). Then source the workspace:

~/ros2_ws/$ colcon build --packages-up-to rclc_examples
~/ros2_ws/$ source ./install/local_setup.bash

It should build these packages:

• rcl_yaml_param_parser
• rcl
• rclc
• rclc_examples

Step 3 Run the example executor.

The binary of the example is example_executor.

~/ros2_ws/$ ros2 run rclc_examples  example_executor

The publisher publishes the message Hello World!in topic_0 at a rate of 1Hz and the subscriber prints out in the callback Callback: I heard: Hello World!.

You should see the following output:

Created timer with timeout 1000 ms.
Created subscriber topic_0:
Debug: number of DDS handles: 2
Published message Hello World!
Callback: I heard: Hello World!
Published message Hello World!
Callback: I heard: Hello World!
Published message Hello World!
Callback: I heard: Hello World!
Published message Hello World!
Callback: I heard: Hello World!
Published message Hello World!
Callback: I heard: Hello World!

Example RCLC-Executor with convenience functions

Step 1 Setup ROS 2 Workspace

Open a terminal with ROS 2 workspace. Assuming that the ROS 2 installation resides in /opt/ros/eloquent, setup the ROS2 environment by:

~$ source /opt/ros/eloquent/setup.bash

Step 2 Build the package Download and build the the packages rclc and rclc_examples in a workspace (for example ros2_ws). Then source the workspace:

~/ros2_ws/$ colcon build --packages-up-to rclc_examples
~/ros2_ws/$ source ./install/local_setup.bash

It should build these packages:

• rcl_yaml_param_parser
• rcl
• rclc
• rclc_examples

Step 3 Run the example executor with the convenience functions from the package rclc.

The binary of the example is example_executor_convenience.

~/ros2_ws/$ ros2 run rclc_examples  example_executor_convenience

The same setup as in the example_executor, just using the RCLC convenience functions. You should see the exact same output:

```C Created timer with timeout 1000 ms. Created subscriber topic_0:

File truncated at 100 lines see the full file

Changelog for package rclc_examples

2.0.6 (2022-01-25)

• [backport galactic, foxy] data_available optimization (#212)

2.0.5 (2021-11-08)

• Bumped version

2.0.4 (2021-08-19)

• Added pingpong example (example for C++ support)

2.0.3 (2021-07-26)

• Bumped version

2.0.2 (2021-07-17)

• Added example for parameter server
• Added example for quality of service entity creation API
• Added example for subscription with context
• Added example for executor_prepare API

2.0.1 (2021-05-28)

• added quality declaration

2.0.0 (2021-04-23)

• added codecov support
• new API of rcl_lifecycle in Rolling required major version bump

1.0.1 (2021-03-29)

• Windows port
• Compatibility sleep function (Windows, POSIX-OS)
• Fixed RCL lifecycle API change for Rolling

1.0.0 (2021-03-04)

• Updated version

0.1.7 (2021-01-20)

• Updated version

0.1.6 (2021-01-20)

• Updated version

0.1.5 (2020-12-11)

• Added support for services,clients and guard_conditions to rclc executor

0.1.4 (2020-11-25)

• Fixed error in bloom release

0.1.3 (2020-11-23)

• Added rclc_lifecycle package

0.1.2 (2020-05-19)

• Fixed compiler errors for bloom release

0.1.1 (2020-05-14)

• Initial release