博客

1.生成头文件

• catkin_create_pkg msg_srv roscpp std_msgs
• cd msg_srv/
• mkdir srv
• roscp rospy_tutorials AddTwoInts.srv srv/AddTwoInts.srv

为了省事复制了一个，内容是：

int64 a

int64 b

—

int64 sum

其中的横线是三个短横线，上面是客户端发给服务端的消息类型，下面是服务端发给客户端的

• 在package.xml加

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

• 修改CMakeLists.txt的若干行

find_package(catkin REQUIRED COMPONENTS roscpp rospy std_msgs message_generation)
catkin_package(
  ...
  CATKIN_DEPENDS message_runtime ...
  ...
)
add_service_files(
  FILES
  AddTwoInts.srv
)
generate_messages(
  DEPENDENCIES
  std_msgs
)

• cd …/…
• catkin_make –pkg msg_srv
• 生成的C++头文件将会放置在~/catkin_ws/devel/include/msg_srv/

2.服务端和客户端

• add_two_ints_server.cpp

#include "ros/ros.h"
#include "msg_srv/AddTwoInts.h"

bool add(msg_srv::AddTwoInts::Request  &req,
         msg_srv::AddTwoInts::Response &res)
{
  res.sum = req.a + req.b;
  ROS_INFO("request: x=%ld, y=%ld", (long int)req.a, (long int)req.b);
  ROS_INFO("sending back response: [%ld]", (long int)res.sum);
  return true;
}

int main(int argc, char **argv)
{
  ros::init(argc, argv, "add_two_ints_server");
  ros::NodeHandle n;

  ros::ServiceServer service = n.advertiseService("add_two_ints", add);
  ROS_INFO("Ready to add two ints.");
  ros::spin();

  return 0;
}

• add_two_ints_client.cpp

#include "ros/ros.h"
#include "msg_srv/AddTwoInts.h"
#include <cstdlib>

int main(int argc, char **argv)
{
  ros::init(argc, argv, "add_two_ints_client");
  if (argc != 3)
  {
    ROS_INFO("usage: add_two_ints_client X Y");
    return 1;
  }

  ros::NodeHandle n;
  ros::ServiceClient client = n.serviceClient<msg_srv::AddTwoInts>("add_two_ints");
  msg_srv::AddTwoInts srv;
  srv.request.a = atoll(argv[1]);
  srv.request.b = atoll(argv[2]);
  if (client.call(srv))
  {
    ROS_INFO("Sum: %ld", (long int)srv.response.sum);
  }
  else
  {
    ROS_ERROR("Failed to call service add_two_ints");
    return 1;
  }

  return 0;
}

• CMakeLists.txt合适位置添加

add_executable(add_two_ints_server src/add_two_ints_server.cpp)
target_link_libraries(add_two_ints_server ${catkin_LIBRARIES})
add_dependencies(add_two_ints_server msg_srv_gencpp)

add_executable(add_two_ints_client src/add_two_ints_client.cpp)
target_link_libraries(add_two_ints_client ${catkin_LIBRARIES})
add_dependencies(add_two_ints_client msg_srv_gencpp)

• 编译成功后，使用以下命令执行

rosrun msg_srv add_two_ints_server
rosrun msg_srv add_two_ints_client 1 39