Hello, I am a beginner in ROS and I have been following the tutorial for simple service and client nodes: http://wiki.ros.org/ROS/Tutorials/WritingServiceClient%28python%29 . After following the tutorial and trying to run the program, I get the following error:

Traceback (most recent call last):
  File "/home/klara/catkin_ws/src/beginner_tutorials/scripts/add_two_ints_server.py", line 5, in <module>
    from beginner_tutorials.srv import AddTwoInts,AddTwoIntsResponse
ImportError: No module named srv

I use Ubuntu 18.04 with ROS melodic, python 2 and catkin. I have sourced the devel/setup.bash so that shouldn't be the problem.

I think the problem is in the service, because everything runs fine when I change
from beginner_tutorials.srv import AddTwoInts,AddTwoIntsResponse to
from rospy_tutorial.srv import AddTwoInts,AddTwoIntsResponse .

I have checked ~/catkin_ws/devel/share/common-lisp/ros/beginner_tutorials/srv/ and it was empty, even though the tutorials say there should be a python script generated there.

I copy pasted the package.xml from rospy_tutorial and changed the package name.

The add_two_ints_server.py is also copy-pasted from the tutorial.

I run catkin_make from catkinws, then source devel/setup.bash, then `rosrun beginnertutorials addtwoints_server.py` and I get the import error.

Thank you in advance for help!

This is my package:

.

├─CMakeLists.txt

├── msg

│   └── Num.msg

├── package.xml

├── scripts

│   ├── add_two_ints_server.py

│   ├── listener.py

│   └── talker.py

└── srv

    └── AddTwoInts.srv

This is my CMakeLists.txt:

cmake_minimum_required(VERSION 3.0.2)

project(beginner_tutorials)

find_package(catkin REQUIRED COMPONENTS
    roscpp
    rospy
    std_msgs
    message_generation
)

add_message_files(
  FILES
  Num.msg
)

add_service_files(
  FILES
  AddTwoInts.srv
 )

generate_messages(
  DEPENDENCIES
   std_msgs  
 )

catkin_package(
  CATKIN_DEPENDS message_runtime 
)

include_directories(
 # ${catkin_INCLUDE_DIRS}
)

catkin_install_python(PROGRAMS
  scripts/talker.py scripts/listener.py scripts/add_two_ints_server.py

 DESTINATION ${CATKIN_PACKAGE_BIN_DESTINATION}
)

catkin_package(
  CATKIN_DEPENDS message_runtime std_msgs # added std_msgs
)