feat: update the naming rules for directories and classes

docs/contributing/coding-guidelines/ros-nodes/class-design.md

@@ -1,5 +1,68 @@
 # Class design
 
+We'll use the `autoware_gnss_poser` package as an example.
+
+## Namespaces
+
+```cpp
+namespace autoware::gnss_poser
+{
+...
+} // namespace autoware::gnss_poser
+```
+
+- Everything should be under `autoware::gnss_poser` namespace.
+- Closing braces must contain a comment with the namespace name. (Automated with `cpplint`)
+
+## Classes
+
+### Nodes
+
+#### `gnss_poser_node.hpp`
+
+```cpp
+class GNSSPoserNode : public rclcpp::Node
+{
+  public:
+    explicit GNSSPoserNode(const rclcpp::NodeOptions & node_options);
+  ...
+}
+```
+
+#### `gnss_poser_node.cpp`
+
+```cpp
+GNSSPoserNode::GNSSPoserNode(const rclcpp::NodeOptions & node_options)
+: Node("gnss_poser", node_options)
+{
+  ...
+}
+```
+
+- The class name should be in `CamelCase`.
+- Node classes should inherit from `rclcpp::Node`.
+- The constructor must be marked be explicit.
+- The constructor must take `rclcpp::NodeOptions` as an argument.
+- Default node name:
+  - should not have `autoware_` prefix.
+  - should **NOT** have `_node` suffix.
+    - **Rationale:** Node names are useful in the runtime. And output of `ros2 node list` will show only nodes anyway. Having `_node` is redundant.
+  - **Example:** `gnss_poser`.
+
+##### Component registration
+
+```cpp
+...
+} // namespace autoware::gnss_poser
+
+#include <rclcpp_components/register_node_macro.hpp>
+RCLCPP_COMPONENTS_REGISTER_NODE(autoware::gnss_poser::GNSSPoserNode)
+```
+
+- The component should be registered at the end of the `gnss_poser_node.cpp` file, outside the namespaces.
+
+### Libraries
+
 !!! warning
 
     Under Construction

docs/contributing/coding-guidelines/ros-nodes/directory-structure.md

@@ -1,75 +1,251 @@
 # Directory structure
 
-!!! warning
+This document describes the directory structure of ROS nodes within Autoware.
 
-    Under Construction
+We'll use the package `autoware_gnss_poser` as an example.
 
 ## C++ package
 
+### Entire structure
+
+- This is a reference on how the entire package might be structured.
+- A package may not have all the directories shown here.
+
 ```txt
-<package_name>
+autoware_gnss_poser
+├─ package.xml
+├─ CMakeLists.txt
+├─ README.md
+│
 ├─ config
-│   ├─ foo_ros.param.yaml
-│   └─ foo_non_ros.yaml
+│   ├─ gnss_poser.param.yaml
+│   └─ another_non_ros_config.yaml
+│
+├─ schema
+│   └─ gnss_poser.schema.json
+│
 ├─ doc
 │   ├─ foo_document.md
 │   └─ foo_diagram.svg
-├─ include
-│   └─ <package_name>
-│       └─ foo_public.hpp
-├─ launch
-│   ├─ foo.launch.xml
-│   └─ foo.launch.py
-├─ schema
-│   └─ foo_node.schema.json
+│
+├─ include  # for exporting headers
+│   └─ autoware
+│       └─ gnss_poser
+│           └─ exported_header.hpp
+│
 ├─ src
-│   ├─ foo_node.cpp
-│   ├─ foo_node.hpp
-│   └─ foo_private.hpp
-├─ test
-│   └─ test_foo.cpp
+│   ├─ include
+│   │   ├─ gnss_poser_node.hpp
+│   │   └─ foo.hpp
+│   ├─ gnss_poser_node.cpp
+│   └─ bar.cpp
+│
+├─ launch
+│   ├─ gnss_poser.launch.xml
+│   └─ gnss_poser.launch.py
+│
+└─ test
+    ├─ test_foo.hpp  # or place under an `include` folder here
+    └─ test_foo.cpp
+```
+
+### Package name
+
+- All the packages in Autoware should be prefixed with `autoware_`.
+- Even if the package is exports a node, the package name **should NOT** have the `_node` suffix.
+- The package name should be in `snake_case`.
+
+| Package Name                      | OK  | Alternative                  |
+| --------------------------------- | --- | ---------------------------- |
+| path_smoother                     | ❌  | autoware_path_smoother       |
+| autoware_trajectory_follower_node | ❌  | autoware_trajectory_follower |
+| autoware_geography_utils          | ✅  | -                            |
+
+### Package folder
+
+```txt
+autoware_gnss_poser
 ├─ package.xml
 ├─ CMakeLists.txt
 └─ README.md
 ```
 
-### Directory descriptions
+The package folder name should be the same as the package name.
 
-#### `config`
+#### `package.xml`
+
+- The package name should be entered within the `<name>` tag.
+  - `<name>autoware_gnss_poser</name>`
+
+#### `CMakeLists.txt`
+
+- The [`project()`](https://cmake.org/cmake/help/latest/command/project.html) command should call the package name.
+  - **Example:** `project(autoware_gnss_poser)`
+
+##### Exporting a composable node component executables
+
+For best practices and system efficiency, it is recommended to primarily use composable node components.
+
+This method facilitates easier deployment and maintenance within ROS environments.
+
+```cmake
+ament_auto_add_library(${PROJECT_NAME} SHARED
+  src/gnss_poser_node.cpp
+)
+
+rclcpp_components_register_node(${PROJECT_NAME}
+  PLUGIN "autoware::gnss_poser::GNSSPoserNode"
+  EXECUTABLE ${PROJECT_NAME}_node
+)
+```
+
+- If you are building:
+  - **only a single composable node component,** the executable name should start with `${PROJECT_NAME}`
+  - **multiple composable node components,** the executable name is up to the developer.
+- All composable node component executables should have the `_node` suffix.
+
+##### Exporting a standalone node executable without composition _(discouraged for most cases)_
+
+Use of standalone executables **should be limited** to cases where specific needs such as debugging or tooling are required.
+
+[Exporting a composable node component executables](#exporting-a-composable-node-component-executables) is generally preferred for standard operational use due its flexibility and scalability within the ROS ecosystem.
+
+Assuming:
 
-Place configuration files such as node parameters.
-For ROS parameters, use the extension `.param.yaml`.
-For non-ROS parameters, use the extension `.yaml`.
+- `src/gnss_poser.cpp` has the `GNSSPoserNode` class.
+- `src/gnss_poser_node.cpp` has the `main` function.
+- There is no composable node component registration.
 
-Rationale: Since ROS parameters files are type-sensitive, they should not be the target of some code formatters and linters. In order to distinguish the file type, we use different file extensions.
+```cmake
+ament_auto_add_library(${PROJECT_NAME} SHARED
+  src/gnss_poser.cpp
+)
 
-#### `doc`
+ament_auto_add_executable(${PROJECT_NAME}_node src/gnss_poser_node.cpp)
+```
 
-Place document files and link from README.
+- The node executable:
+  - should have `_node` suffix.
+  - should start with `${PROJECT_NAME}
 
-#### `include`
+### `config` and `schema`
 
-Place header files exposed to other packages. Do not place files directly under the `include` directory, but place files under the directory with the package name.
-This directory is used for mostly library headers. Note that many headers do not need to be placed here. It is enough to place the headers under the `src` directory.
+```txt
+autoware_gnss_poser
+│─ config
+│   ├─ gnss_poser.param.yaml
+│   └─ another_non_ros_config.yaml
+└─ schema
+    └─ gnss_poser.schema.json
+```
 
-Reference: <https://docs.ros.org/en/humble/How-To-Guides/Ament-CMake-Documentation.html#adding-targets>
+#### `config`
 
-#### `launch`
+- ROS parameters uses the extension `.param.yaml`.
+- Non-ROS parameters use the extension `.yaml`.
 
-Place launch files (`.launch.xml` and `.launch.py`).
+**Rationale:** Different linting rules are used for ROS parameters and non-ROS parameters.
 
 #### `schema`
 
-Place parameter definition files. See [parameters](./parameters.md) for details.
+Place parameter definition files. See [Parameters](./parameters.md) for details.
+
+### `doc`
+
+```txt
+autoware_gnss_poser
+└─ doc
+    ├─ foo_document.md
+    └─ foo_diagram.svg
+```
+
+Place documentation files and link them from the README file.
+
+### `include` and `src`
+
+- Unless you specifically need to export headers, you shouldn't have a `include` directory under the package directory.
+- For most cases, follow [Not exporting headers](#not-exporting-headers).
+- Library packages that export headers may follow [Exporting headers](#exporting-headers).
+
+#### Not exporting headers
+
+```txt
+autoware_gnss_poser
+└─ src
+    ├─ include
+    │   ├─ gnss_poser_node.hpp
+    │   └─ foo.hpp
+    │─ gnss_poser_node.cpp
+    └─ bar.cpp
+
+OR
+
+autoware_gnss_poser
+└─ src
+    ├─ gnss_poser_node.hpp
+    ├─ gnss_poser_node.cpp
+    ├─ foo.hpp
+    └─ bar.cpp
+```
+
+- The source file exporting the node should:
+  - have `_node` suffix.
+    - **Rationale:** To distinguish from other source files.
+  - **NOT** have `autoware_` prefix.
+    - **Rationale:** To avoid verbosity.
+- See [Classes](../../class-design.md) for more details on how to construct `gnss_poser_node.hpp` and `gnss_poser_node.cpp` files.
+- It is up to developer how to organize the source files under `src`.
+  - **Note:** The `include` folder under `src` is optional.
 
-#### `src`
+#### Exporting headers
 
-Place source files and private header files.
+```txt
+autoware_gnss_poser
+└─ include
+    └─ autoware
+        └─ gnss_poser
+            └─ exported_header.hpp
+```
+
+- `autoware_gnss_poser/include` folder should contain **ONLY** the `autoware` folder.
+  - **Rationale:** When installing ROS debian packages, the headers are copied to the `/opt/ros/$ROS_DISTRO/include/` directory. This structure is used to avoid conflicts with non-Autoware packages.
+- `autoware_gnss_poser/include/autoware` folder should contain **ONLY** the `gnss_poser` folder.
+  - **Rationale:** Similarly, this structure is used to avoid conflicts with other packages.
+- `autoware_gnss_poser/include/autoware/gnss_poser` folder should contain the header files to be exported.
+
+**Note:** If `ament_auto_package()` command is used in the `CMakeLists.txt` file and `autoware_gnss_poser/include` folder exists,
+this `include` folder will be exported to the `install` folder as part of [ament_auto_package.cmake](https://github.com/ament/ament_cmake/blob/79cc237f8eb819edf4c1c624b56451e0a05a45f8/ament_cmake_auto/cmake/ament_auto_package.cmake#L62-L66)
+
+**Reference:** <https://docs.ros.org/en/humble/How-To-Guides/Ament-CMake-Documentation.html#adding-targets>
+
+### `launch`
+
+```txt
+autoware_gnss_poser
+└─ launch
+    ├─ gnss_poser.launch.xml
+    └─ gnss_poser.launch.py
+```
+
+- You may have multiple launch files here.
+- Unless you have a specific reason, use the `.launch.xml` extension.
+  - **Rationale:** While the `.launch.py` extension is more flexible, it comes with a readability cost.
+- Avoid `autoware_` prefix in the launch file names.
+  - **Rationale:** To avoid verbosity.
 
-#### `test`
+### `test`
+
+```txt
+autoware_gnss_poser
+└─ test
+    ├─ test_foo.hpp  # or place under an `include` folder here
+    └─ test_foo.cpp
+```
 
 Place source files for testing. See [unit testing](../../testing-guidelines/unit-testing.md) for details.
 
 ## Python package
 
-T.B.D.
+!!! warning
+
+    Under Construction

docs/contributing/coding-guidelines/ros-nodes/parameters.md

@@ -11,7 +11,7 @@ Find more information on parameters from the official ROS documentation:
 
 A ROS package which uses the [declare_parameter(...)](https://docs.ros.org/en/ros2_packages/humble/api/rclcpp/generated/classrclcpp_1_1Node.html#_CPPv4N6rclcpp4Node17declare_parameterERKNSt6stringERKN6rclcpp14ParameterValueERKN14rcl_interfaces3msg19ParameterDescriptorEb) function should:
 
-- use the [declare_parameter(...)](https://docs.ros.org/en/ros2_packages/humble/api/rclcpp/generated/classrclcpp_1_1Node.html#_CPPv4N6rclcpp4Node17declare_parameterERKNSt6stringERKN6rclcpp14ParameterValueERKN14rcl_interfaces3msg19ParameterDescriptorEb) with out a default value
+- use the [declare_parameter(...)](https://docs.ros.org/en/ros2_packages/humble/api/rclcpp/generated/classrclcpp_1_1Node.html#_CPPv4N6rclcpp4Node17declare_parameterERKNSt6stringERKN6rclcpp14ParameterValueERKN14rcl_interfaces3msg19ParameterDescriptorEb) without a default value
 - create a parameter file
 - create a schema file