While using services in ROS2, we include example_interfaces/srv/add_two_ints.hpp in the server.cpp and client.cpp files. How is this file generated.

In my case, i created a new service file heatFlow.srv and changed the CMakeLists.txt file and the cpp files accordingly. But when i try to build the package, it gives a fatal error : fatal error: example_interfaces/srv/heatFlow.hpp: No such file or directory compilation terminated.

How are these .hpp files basically generated ?

EDIT :

I created a new folder "example_interface" (note: without S in the end) and created a new service file called heatFlow.srv. Now the CMakeLists is as follows :

cmake_minimum_required(VERSION 3.5)
project(example_interface)
# Default to C++14
if(NOT CMAKE_CXX_STANDARD)
set(CMAKE_CXX_STANDARD 14)
endif()
if(CMAKE_COMPILER_IS_GNUCXX OR CMAKE_CXX_COMPILER_ID MATCHES "Clang")
# we dont use add_compile_options with pedantic in message packages
# because the Python C extensions dont comply with it
set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -Wall -Wextra -Wpedantic")
endif()
find_package(ament_cmake REQUIRED)
find_package(rosidl_default_generators REQUIRED)
rosidl_generate_interfaces(${PROJECT_NAME}
"srv/heatFlow.srv"
)
ament_export_dependencies(rosidl_default_runtime)
install(FILES mapping_rules.yaml DESTINATION share/${PROJECT_NAME})
ament_package()

and the package.xml as follows:

 > <?xml version="1.0"?>
 <?xml-model href="http://download.ros.org/schema/package_format3.xsd" schematypens="http://www.w3.org    /2001/XMLSchema"?>
 <package format="3">
 <name>example_interface</name>
 <version>0.4.0</version>
 <description>Contains message and service definitions used by the examples.</description>
 <maintainer email="dthomas@osrfoundation.org">Dirk Thomas</maintainer>
 <license>Apache License 2.0</license>
 <buildtool_depend>ament_cmake</buildtool_depend>
 <buildtool_depend>rosidl_default_generators</buildtool_depend>
 <exec_depend>rosidl_default_runtime</exec_depend>
 <member_of_group>rosidl_interface_packages</member_of_group>
 <export>
 <build_type>ament_cmake</build_type>
 <ros1_bridge mapping_rules="mapping_rules.yaml"/>
 </export>
 </package>

When I compile it using : ament build --symlink-install --only-package heatflow_cpp, it gives an error `CMake Error at CMakeLists.txt:15 (findpackage): By not providing "Findexampleinterface.cmake" in CMAKEMODULEPATH this project has asked CMake to find a package configuration file provided by "example_interface", but CMake did not find one.

Could not find a package configuration file provided by "example_interface" with any of the following names:

example_interfaceConfig.cmake
example_interface-config.cmake

Add the installation prefix of "exampleinterface" to CMAKEPREFIXPATH or set "exampleinterfaceDIR" to a directory containing one of the above files. If "exampleinterface" provides a separate development package or SDK, be sure it has been installed.`

  <depend>aes_custom_interface</depend>

find_package(aes_custom_interface REQUIRED)
ament_target_dependencies(${PROJECT_NAME}
                          ...
                          aes_custom_interface)