(api_development)=

# API Development

To utilize the RVC API, follow the steps outlined below:

Start by creating a ROS package:

```bash
ros2 pkg create --build-type ament_cmake <package_name>
```

Next, add the following line to your `package.xml`:

```xml
<depend>rvc_messages</depend>
```

Lastly, add the following lines to the corresponding sections in your `CmakeLists.txt`:

```cmake
find_package(rvc_messages REQUIRED)
ament_target_dependencies(${PROJECT_NAME_PLUGIN}
[...]
rvc_messages
)
```

As a rule of thumb, we suggest using [sensor data](https://docs.ros.org/en/rolling/Concepts/Intermediate/About-Quality-of-Service-Settings.html) as the Quality of Service when creating subscriptions and/or publishers.

Typically, the publisher, usually part of the RVC Vision component, will publish the RVC API message upon detection.

```cpp
m_pub_poses = this->create_publisher<rvc_messages::msg::PoseStampedList>("object_poses", qos);
[...]
rvc_messages::msg::PoseStampedList outMsg;
rvc_messages::msg::PoseStamped poseStamped;
poseStamped.pose_stamped.header.stamp = now();
[...]
outMsg.poses.push_back(poseStamped);
m_pub_poses->publish(outMsg);
```