Custom Message Creation and Publisher and Subsciber

Messages

Create a srv folder inside session3_cliserver folder

mkdir -p ~/ros_workshop/src/session3_cliserver/srv

Open the folder

cd ~/ros_workshop/src/session3_cliserver/srv

Create a .srv file with desired name. (we will select custom.srv as an example)

code custom.srv

Inside the file add following lines, then save and close.

uint8 a
uint8 b
---
uint16 result

Open package.xml and add the following lines in the respective sections

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

Open the CMakeLists.txt and add following lines to respective section,

message_generation to find_package()

find_package(catkin REQUIRED COMPONENTS
   roscpp
   rospy
   std_msgs
   message_generation
)

message_runtime to catkin_package

catkin_package(
  ...
  CATKIN_DEPENDS message_runtime ...
  ...)

uncomment add_service_files section and add custom.srv file

add_service_files(DIRECTORY 
  srv
  FILES
  custom.srv
)

uncomment generate_messgae() section. It shoul look like this,

generate_messages(
  DEPENDENCIES
  std_msgs
)

Move to the workspace root and rebuild

cd ~/ros_workshop/

catkin build

catkin_make