======ROS 스터디 #5: ROS 기초 프로그래밍======
2020년 11월 27일 금요일 13:30\\
ZOOM 화상회의
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=====3. 서비스(Service) 서버 <-> 클라이언트 노드=====

====3.1. 패키지 생성====
<sxh bash>
$cd ~/catkin_ws/src
$catkin_create_pkg ros_tutorials_service message_generation std_msgs roscpp
</sxh>

====3.2. 패키지 설정 파일(package.xml) 수정====
<sxh>
$ gedit package.xml
</sxh>
<sxh xml title:ros_tutorials_service/package.xml>
<?xml version="1.0"?>
<package>
  <name>ros_tutorials_topic</name>
  <version>0.1.0</version>
  <description>ROS turtorial package to learn the topic</description>
  <license>Apache License 2.0</license>
  <author email="pyo@robotis.com">Yoonseok Pyo</author>
  <maintainer email="pyo@robotis.com">Yoonseok Pyo</maintainer>
  <url type="bugtracker">https://github.com/ROBOTIS-GIT/ros_tutorials/issues</url>
  <url type="repository">https://github.com/ROBOTIS-GIT/ros_tutorials.git</url>
  <url type="website">http://www.robotis.com</url>
  <buildtool_depend>catkin</buildtool_depend>
  <build_depend>roscpp</build_depend>
  <build_depend>std_msgs</build_depend>
  <build_depend>message_generation</build_depend>
  <run_depend>roscpp</run_depend>
  <run_depend>std_msgs</run_depend>
  <run_depend>message_runtime</run_depend>
  <export></export>
</package>
</sxh>

====3.3. 빌드 설정 파일(CMakeLists.txt) 수정====
<sxh>
$ gedit CMakeLists.txt
</sxh>
<sxh cpp title:ros_tutorials_servise/CMakeLists.txt>
cmake_minimum_required(VERSION 2.8.3)
project(ros_tutorials_service)

find_package(catkin REQUIRED COMPONENTS message_generation std_msgs roscpp)

add_service_files(FILES SrvTutorial.srv)
generate_messages(DEPENDENCIES std_msgs)


catkin_package(
  LIBRARIES ros_tutorials_service
  CATKIN_DEPENDS std_msgs roscpp
)

include_directories(${catkin_INCLUDE_DIRS})

add_executable(service_server src/service_server.cpp)
add_dependencies(service_server${${PROJECT_NAME}_EXPORTED_TARGETS}${catkin_EXPORTED_TARGETS)
target_link_libraries(topic_publisher ${catkin_LIBRARIES})

add_executable(service_client src/service_client.cpp)
add_dependencies(service_client ${${PROJECT_NAME}_EXPORTED_TARGETS} ${catkin_EXPORTED_TARGETS})
target_link_libraries(service_client ${catkin_LIBRARIES})
</sxh>


====3.4. service 파일 등록====
<sxh>

$ roscd ros_tutorials_service
$ mkdir srv
$ cd srv
$ gedit SrvTutorial.srv

</sxh>

<sxh cpp title:ros_tutorials_service/srv/SrvTutorial.srv>
int64 a
int64 b
---
int64 result
</sxh>


====3.5. service server 노드 작성====
<sxh>
$ add roscd ros_tutorials_service/src
$ gedit service_server.cpp
</sxh>
<sxh cpp title:ros_tutorials_service/src/service_server.cpp>
#include "ros/ros.h"                            // ROS Default Header File
#include "ros_tutorials_service/SrvTutorial.h"    // SrvTutorial Message File Header. The header file is automatically created when building the package.

bool calculation(ros_tutorials_service::Srvtutorial::Request&req, ros_tutorials_service::SrvTutorial::Response&res) 
res.result=req.a+req.b;
ROS_INFO("request: x=%ld, y=%ld", (long int)req.a, (iong int)req.b);\
ROS_INFO("sending back response: %ld", (long int)res.result);

return true;
}

int main(int argc, char **argv)                 // Node Main Function
{
  ros::init(argc, argv, "topic_publisher");     // Initializes Node Name
  ros::NodeHandle nh;                           // Node handle declaration for communication with ROS system

  ros::ServiceServer ros_tutorials_service_server=nh.advertiseService("ros_tutorial_srv", calculation);
  
  ROS_INFO("ready srv server!");
  
  ros::spin();
  
  return 0;
}
</sxh>

====3.6. service client 노드 작성====
<sxh>
$ add roscd ros_tutorials_service/src
$ gedit service_client.cpp
</sxh>
<sxh cpp title:ros_tutorials_service/src/service_client.cpp>
#include "ros/ros.h"                          // ROS Default Header File
#include "ros_tutorials_service/SrvTutorial.h"  // MsgTutorial Message File Header. The header file is automatically created when building the package.
#include<cstdlib>                              // Library for Using atroll Function

int main(int argc, char **argv)                         // Node Main Function
{
ros::init(argc, argv, "service_client");            // Initializes Node Name

if(argc!=3)
{ROS_INFO("cmd : rosrun ros_tutorial_service service_client arg0 argl");
 ROS_INFO("arg0: double number, argl: double number");
 return 1;
}

  ros::NodeHandle nh;                                   // Node handle declaration for communication with ROS system

  // Declares service client. Create subscriber 'ros_tutorial_service' using the 'SrvTutorial'
  // message file from the 'ros_tutorials_service_client' package. The topic name is
  // 'ros_tutorial_srv' 

 ros::ServiceClient ros_tutorials_service_client=nh.serviceClient<"ros_tutorials_service::SrnTutorial>("ros_tutorial_srv");
 
ros_tutorials_service::SrvTutorial srv;

srv.request.a=atill(argv[1]);
srv.request.b=atill(argv[2]);

if(ros_tutorials_service_client.call(srv))
 {
  ROS_INFO("send srv,srv.Request.a and b: %ld, %ld", (long int)srv.request.a, (long int)srv.request.b);
  ROS_INFO("receive srv,srv.Response.result: %ld, (long int)srv.response.result);
 }
 else
 {
  ROS_ERROR("Failed to call service ros_tutorial_srv");
  return 1;
 }
 return 0;
}


</sxh>


====3.7. 실행 후 확인====
<sxh>

$ cd ~/catkin_ws && catkin_make

$ rosrun ros_tutorials_service service_server
[INFO][149572654.268629564]: ready srv server!

$ rosrun ros_tutorials_service service_client
[INFO][149572654.268629564]: send srv, srv.Request.a and b: 2, 3
[INFO][149572654.268629564]: receive.srv, srv.Response.result: 5

</sxh>
=====4. 액션(Action) 서버 <-> 클라이언트 노드=====


=====5. roslaunch 사용법=====


====5.1. 예시 1====
<sxh>
$ roscd ros tutorials_topic
$ mkdirlaunch
$ cd launch
$ gedit union.launch
</sxh>

<sxh cpp title: union.launch>
<launch>
 <node pkg="ros_tutorials_topic" type="topic_publisher" name="topic_publisher1"/>
 <node pkg="ros_tutorials_topic" type="topic_publisher" name="topic_subscriber1"/>
 <node pkg="ros_tutorials_topic" type="topic_publisher" name="topic_publisher2"/>
 <node pkg="ros_tutorials_topic" type="topic_publisher" name="topic_subscriber2"/>
</sxh>

====5.2. 예시 2====
<sxh>
$ roscd ros tutorials_topic/launch
$ gedit union.launch
</sxh>

<sxh cpp title: union.launch>
<launch>
 <group ns="ns1">
  <node pkg="ros_tutorials_topic" type="topic_publisher" name="topic_publisher1"/>
  <node pkg="ros_tutorials_topic" type="topic_publisher" name="topic_subscriber1"/>
 </group>

 <group ns="ns2">
  <node pkg="ros_tutorials_topic" type="topic_publisher" name="topic_publisher2"/>
  <node pkg="ros_tutorials_topic" type="topic_publisher" name="topic_subscriber2"/>
 </group>
</sxh>