In CMakeLists configuration for saving spots to files

Course Support Mastering with ROS - SUMMITXL
1

The provided code is :

add_service_files(
FILES
MyCustomServiceMessage.srv
)

but there is no MyCustomServiceMessage in the srv directory.

Is that supposed to be SummitXLPose.srv ??

And . . . if it is, where do we get SummitXLPoseResponse and SummitXLPoseRequest from in the following line of the python service script ?

from my_summit_xl_tools.srv import SummitXLPose, SummitXLPoseResponse, SummitXLPoseRequest

2

Hello @adeoduye ,

Yes, that’s an error in the notebook. The message file is SummitXLPose.srv. Whenever you compile a Service message (.srv), 2 extra messages are generated, which correspond to the request and response messages of a service (you can learn more about this in the ROS Basics course). These messages are:

<your_service_msg>Request - the request part of the message
<your_service_msg>Response - the response part of the message

Hope this helps,

1 Like
3

Grasias Alberto.

But I have a problem with the extra messages. They are not being generated.

I have this in package.xml:

<build_depend>message_generation</build_depend>
<build_export_depend>message_generation</build_export_depend>
<exec_depend>message_runtime</exec_depend>

<buildtool_depend>catkin</buildtool_depend>
<build_depend>rospy</build_depend>
<build_export_depend>rospy</build_export_depend>
<exec_depend>rospy</exec_depend>

And in CMakeList.txt:

cmake_minimum_required(VERSION 3.0.2)
project(my_summit_xl_tools)

find_package(catkin REQUIRED COMPONENTS
rospy
std_msgs
message_generation
)

Generate services in the ‘srv’ folder

add_service_files(
FILES
SummitXLPose.srv
)

Generate added messages and services with any dependencies listed here

generate_messages(
DEPENDENCIES
std_msgs # Or other packages containing msgs
)

catkin_package(

INCLUDE_DIRS include

LIBRARIES my_summit_xl_tools

CATKIN_DEPENDS
rospy

DEPENDS system_lib

)

include_directories(

include

${catkin_INCLUDE_DIRS}
)

And the script, as copied and pasted, generates an error:

user:~/catkin_ws$ rosrun my_summit_xl_tools spots_to_file.py

Traceback (most recent call last):
File “/home/user/catkin_ws/src/my_summit_xl_tools/src/spots_to_file.py”, line 4, in
from my_summit_xl_tools.srv import SummitXLPose, SummitXLPoseResponse, SummitXLPoseRequest
ImportError: No module named my_summit_xl_tools.srv

4

Hello @adeoduye ,

Have you compiled and sourced the web shells before trying to run the program?

catkin_make
source ~/catkin_ws/devel/setup.bash

This is mandatory so that your program can find the messages. Maybe it would also be a good idea to have a look at the Services Units in the ROS Basics in 5 Days course so that you can better understand how services (and services messages) work.

Best,