ROS2 cannot load custom my_package.srv

edit

I am trying to add my custom service to my_package. I created a 'srv' folder under 'my_package' and add "Battery.srv" as below

---
float64 volt
float64 SOC
float64 current

and added followings to package.xml

  <build_depend>rosidl_default_generators</build_depend>
  <exec_depend>rosidl_default_runtime</exec_depend>
  <member_of_group>rosidl_interface_packages</member_of_group>

and in CMakeLists.txt

find_package(builtin_interfaces REQUIRED)
find_package(rosidl_default_generators REQUIRED)

rosidl_generate_interfaces(${PROJECT_NAME}
  "srv/Battery.srv"
)

Also in my setup.py

setup(
    name=package_name,
    version='0.0.1',
    packages=find_packages(exclude=[]),
    data_files=[
        ('share/ament_index/resource_index/packages', ['resource/' + package_name]),
        ('share/' + package_name, ['package.xml']),
        (os.path.join('share', package_name, 'launch'), glob(os.path.join('launch', '*.launch.py'))),
        (os.path.join('share', package_name, 'param'), glob(os.path.join('param', '*.yaml'))),
        (os.path.join('share', package_name, 'srv'), glob(os.path.join('srv', '*.srv'))),
    ],

Finally in my package_node.py I tried to import

from my_package.srv import Battery

After colcon build this package successfully, to checked my service I entered below

 $ ros2 interface show my_package/srv/Battery
---
float64 volt
float64 SOC
float64 current

Now when I tried to run my package node I got error like this

File "/home/my/ros2_ws/build/my_package/my_package/scripts/my_package_node.py", line 14, in <module>
    from my_package.srv import Battery
ModuleNotFoundError: No module named 'my_package.srv'

Is there anything wrong with my practice? Any advice would be much appreciated. Kyu