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大纲
- 初始化环境
- 生成自定义服务的工程
- 创建包
- 自定义消息
- package.xml
- 完整文件
- CMakeLists.txt
- 完整文件
- 编译
- 注册
- 使用自定义服务的工程
- 创建包
- 代码
- CMakeLists.txt
- 编译
- 运行
- 工程地址
- 参考资料
在《Robot Operating System——自定义订阅/发布的消息结构》一文中,我们讲解了如何自定义消息结构。这个消息是发布者向订阅者发送的消息,具有单向性。但是Service/Client类型的消息是具有双向性的。Client向Service发送的是Request消息,Service向Client发送的是Response消息。
初始化环境
在《Robot Operating System——深度解析自动隐式加载动态库的运行模式》一文中,我们展现了ROS2可执行文件的链接指令。可以看到它依赖了很多ROS2环境相关的动态库,所以我们在创建工程之前也要初始化环境。
source /opt/ros/jazzy/setup.bash
关于环境的安装可以参见《Robot Operating System——Ubuntu上以二进制形式安装环境》。
生成自定义服务的工程
创建包
ros2 pkg create --build-type ament_cmake --license Apache-2.0 custom_service
其目录结构如下
自定义消息
我们创建一个目录srv,然后在其下新建一个文件NavSatPose.srv,填入下面的内容
sensor_msgs/NavSatStatus nav
---
geometry_msgs/PoseWithCovariance pose
std_msgs/Bool boolvalue
nav是Request消息结构体中的内容;pose和boolvalue是Response消息结构体中的内容。
package.xml
在该文件中新增如下内容
<depend>sensor_msgs</depend><depend>geometry_msgs</depend><depend>std_msgs</depend><buildtool_depend>rosidl_default_generators</buildtool_depend><exec_depend>rosidl_default_runtime</exec_depend><member_of_group>rosidl_interface_packages</member_of_group>
sensor_msgs、geometry_msgs和std_msgs是消息体中用的三种ROS2提供的基础消息类型;
rosidl_default_generators用于将上述msg文件生成代码;
rosidl_default_runtime是运行时依赖;
后三者是一定要加的,前面的三个根据自定义消息的类型酌情添加。
此时的目录结构如下
完整文件
<?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>custom_service</name><version>0.0.0</version><description>TODO: Package description</description><maintainer email="f304646673@gmail.com">fangliang</maintainer><license>Apache-2.0</license><buildtool_depend>ament_cmake</buildtool_depend><depend>sensor_msgs</depend><depend>geometry_msgs</depend><depend>std_msgs</depend><buildtool_depend>rosidl_default_generators</buildtool_depend><exec_depend>rosidl_default_runtime</exec_depend><member_of_group>rosidl_interface_packages</member_of_group><test_depend>ament_lint_auto</test_depend><test_depend>ament_lint_common</test_depend><export><build_type>ament_cmake</build_type></export>
</package>
CMakeLists.txt
新增如下内容
find_package(sensor_msgs REQUIRED)
find_package(geometry_msgs REQUIRED)
find_package(std_msgs REQUIRED)
find_package(rosidl_default_generators REQUIRED)rosidl_generate_interfaces(${PROJECT_NAME}"srv/NavSatPoseBool.srv"DEPENDENCIES sensor_msgs geometry_msgs std_msgs
)
DEPENDENCIES 中添加的是我们自定义消息的基础类型。
完整文件
cmake_minimum_required(VERSION 3.8)
project(custom_service)if(CMAKE_COMPILER_IS_GNUCXX OR CMAKE_CXX_COMPILER_ID MATCHES "Clang")add_compile_options(-Wall -Wextra -Wpedantic)
endif()# find dependencies
find_package(ament_cmake REQUIRED)
# uncomment the following section in order to fill in
# further dependencies manually.
# find_package(<dependency> REQUIRED)find_package(sensor_msgs REQUIRED)
find_package(geometry_msgs REQUIRED)
find_package(std_msgs REQUIRED)
find_package(rosidl_default_generators REQUIRED)rosidl_generate_interfaces(${PROJECT_NAME}"srv/NavSatPoseBool.srv"DEPENDENCIES sensor_msgs geometry_msgs std_msgs
)if(BUILD_TESTING)find_package(ament_lint_auto REQUIRED)# the following line skips the linter which checks for copyrights# comment the line when a copyright and license is added to all source filesset(ament_cmake_copyright_FOUND TRUE)# the following line skips cpplint (only works in a git repo)# comment the line when this package is in a git repo and when# a copyright and license is added to all source filesset(ament_cmake_cpplint_FOUND TRUE)ament_lint_auto_find_test_dependencies()
endif()ament_package()
编译
colcon build --packages-select custom_service
注册
source install/setup.sh
经过注册后,我们可以在ROS2中查看这个自定义服务
ros2 interface show custom_service/srv/NavSatPoseBool
使用自定义服务的工程
创建包
ros2 pkg create --build-type ament_cmake --license Apache-2.0 custom_service_nodes --dependencies rclcpp custom_service
–dependencies参数可以帮我们在package.xml和CMakeLists.txt中自动添加相应依赖。此时我们添加上一步创建的custom_service。
此时目录结构如下
代码
在src目录下新建server.cpp和client.cpp,分别填入以下内容
#include "rclcpp/rclcpp.hpp"
#include "custom_service/srv/nav_sat_pose_bool.hpp"#include <memory>
#include <string>
#include <sstream>std::string serializeRequest(const custom_service::srv::NavSatPoseBool::Request &request) {std::ostringstream oss;oss << request.nav.service << " " << request.nav.status << " ";return oss.str();
}std::string serializeResponse(const custom_service::srv::NavSatPoseBool::Response &response) {std::ostringstream oss;oss << response.pose.pose.position.x << " " << response.pose.pose.position.y << " " << response.pose.pose.position.z << " " << response.pose.pose.orientation.x << " " << response.pose.pose.orientation.y << " " << response.pose.pose.orientation.z << " " << response.pose.pose.orientation.w << " " << response.boolvalue.data;return oss.str();
}void handle(const std::shared_ptr<custom_service::srv::NavSatPoseBool::Request> request, std::shared_ptr<custom_service::srv::NavSatPoseBool::Response> response)
{response->pose.pose.position.x = 1.0;response->pose.pose.position.y = 2.0;response->pose.pose.position.z = 3.0;response->pose.pose.orientation.x = 4.0;response->pose.pose.orientation.y = 5.0;response->pose.pose.orientation.z = 6.0;response->pose.pose.orientation.w = 7.0;response->boolvalue.data = true;RCLCPP_INFO(rclcpp::get_logger("rclcpp"), "Incoming request\na: %s", serializeRequest(*request).c_str()); RCLCPP_INFO(rclcpp::get_logger("rclcpp"), "sending back response: [%s]", serializeResponse(*response).c_str());
}int main(int argc, char **argv)
{rclcpp::init(argc, argv);std::shared_ptr<rclcpp::Node> node = rclcpp::Node::make_shared("custom_server"); rclcpp::Service<custom_service::srv::NavSatPoseBool>::SharedPtr service = node->create_service<custom_service::srv::NavSatPoseBool>("handle", &handle); RCLCPP_INFO(rclcpp::get_logger("rclcpp"), "Ready to start service."); rclcpp::spin(node);rclcpp::shutdown();
}
#include "rclcpp/rclcpp.hpp"
#include "custom_service/srv/nav_sat_pose_bool.hpp"#include <chrono>
#include <cstdlib>
#include <memory>using namespace std::chrono_literals;std::string serializeRequest(const custom_service::srv::NavSatPoseBool::Request &request) {std::ostringstream oss;oss << request.nav.service << " " << request.nav.status << " ";return oss.str();
}std::string serializeResponse(const custom_service::srv::NavSatPoseBool::Response &response) {std::ostringstream oss;oss << response.pose.pose.position.x << " " << response.pose.pose.position.y << " " << response.pose.pose.position.z << " " << response.pose.pose.orientation.x << " " << response.pose.pose.orientation.y << " " << response.pose.pose.orientation.z << " " << response.pose.pose.orientation.w << " " << response.boolvalue.data;return oss.str();
}int main(int argc, char **argv)
{rclcpp::init(argc, argv);std::shared_ptr<rclcpp::Node> node = rclcpp::Node::make_shared("custom_client"); rclcpp::Client<custom_service::srv::NavSatPoseBool>::SharedPtr client = node->create_client<custom_service::srv::NavSatPoseBool>("handle"); auto request = std::make_shared<custom_service::srv::NavSatPoseBool::Request>();request->nav.service = 1;request->nav.status = 2; while (!client->wait_for_service(1s)) {if (!rclcpp::ok()) {RCLCPP_ERROR(rclcpp::get_logger("rclcpp"), "Interrupted while waiting for the service. Exiting.");return 0;}RCLCPP_INFO(rclcpp::get_logger("rclcpp"), "service not available, waiting again...");}auto result = client->async_send_request(request);RCLCPP_INFO(rclcpp::get_logger("rclcpp"), "sending request: [%s]", serializeRequest(*request).c_str());// Wait for the result.if (rclcpp::spin_until_future_complete(node, result) ==rclcpp::FutureReturnCode::SUCCESS){RCLCPP_INFO(rclcpp::get_logger("rclcpp"), "receiving back response: [%s]", serializeResponse(*result.get()).c_str());} else {RCLCPP_ERROR(rclcpp::get_logger("rclcpp"), "Failed to call service custom_server"); }rclcpp::shutdown();return 0;
}
CMakeLists.txt
然后分别编译这两个文件成为可自行文件。
add_executable(server src/server.cpp)
ament_target_dependencies(server rclcpp custom_service)add_executable(client src/client.cpp)
ament_target_dependencies(client rclcpp custom_service)install(TARGETSserverclientDESTINATION lib/${PROJECT_NAME})
编译
colcon build --packages-select custom_service_nodes
运行
在新的终端中,需要先初始化环境
source custom_service_nodes/install/setup.sh
然后执行server和client
工程地址
- https://github.com/f304646673/ros2-examples/tree/main/custom_service
- https://github.com/f304646673/ros2-examples/tree/main/custom_service_nodes
参考资料
- https://docs.ros.org/en/jazzy/Tutorials/Beginner-Client-Libraries/Custom-ROS2-Interfaces.html
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