配置服务自省

目标：为服务客户端和服务器配置服务自检。

教程级别：高级

时间：15 分钟

概述

ROS 2 应用程序通常由在远程节点中执行特定程序的服务组成。

可以使用服务自省来自省服务数据通信。

在此演示中，我们将重点介绍如何为服务客户端和服务器配置服务自省状态，并使用“ros2 service echo”监视服务通信。

安装演示

有关安装 ROS 2 的详细信息，请参阅 安装说明。

如果您已安装 ROS 2 二进制包，请确保已安装“ros-rolling-demo-nodes-cpp”。

如果您下载了存档或从源代码构建了 ROS 2，它将已经成为安装的一部分。

自省配置状态

服务自省有 3 种配置状态。

Service Introspection Configuration State

RCL_SERVICE_INTROSPECTION_OFF	Disabled
RCL_SERVICE_INTROSPECTION_METADATA	Only metadata without any user data contents
RCL_SERVICE_INTROSPECTION_CONTENTS	User data contents with metadata

自省演示

此演示展示了如何使用“ros2 service echo”来管理服务自省并监控服务数据通信。

自省服务节点：

https://github.com/ros2/demos/blob/rolling/demo_nodes_cpp/src/services/introspection_service.cpp

namespace demo_nodes_cpp
{

class IntrospectionServiceNode : public rclcpp::Node
{
public:
  DEMO_NODES_CPP_PUBLIC
  explicit IntrospectionServiceNode(const rclcpp::NodeOptions & options)
  : Node("introspection_service", options)
  {
    auto handle_add_two_ints =
      [this](const std::shared_ptr<rmw_request_id_t> request_header,
        const std::shared_ptr<example_interfaces::srv::AddTwoInts::Request> request,
        std::shared_ptr<example_interfaces::srv::AddTwoInts::Response> response) -> void
      {
        (void)request_header;
        RCLCPP_INFO(
          this->get_logger(), "Incoming request\na: %" PRId64 " b: %" PRId64,
          request->a, request->b);
        response->sum = request->a + request->b;
      };
    // Create a service that will use the callback function to handle requests.
    srv_ = create_service<example_interfaces::srv::AddTwoInts>("add_two_ints", handle_add_two_ints);

    auto on_set_parameter_callback =
      [](std::vector<rclcpp::Parameter> parameters) {
        rcl_interfaces::msg::SetParametersResult result;
        result.successful = true;
        for (const rclcpp::Parameter & param : parameters) {
          if (param.get_name() != "service_configure_introspection") {
            continue;
          }

          if (param.get_type() != rclcpp::ParameterType::PARAMETER_STRING) {
            result.successful = false;
            result.reason = "must be a string";
            break;
          }

          if (param.as_string() != "disabled" && param.as_string() != "metadata" &&
            param.as_string() != "contents")
          {
            result.successful = false;
            result.reason = "must be one of 'disabled', 'metadata', or 'contents'";
            break;
          }
        }

        return result;
      };

    auto post_set_parameter_callback =
      [this](const std::vector<rclcpp::Parameter> & parameters) {
        for (const rclcpp::Parameter & param : parameters) {
          if (param.get_name() != "service_configure_introspection") {
            continue;
          }

          rcl_service_introspection_state_t introspection_state = RCL_SERVICE_INTROSPECTION_OFF;

          if (param.as_string() == "disabled") {
            introspection_state = RCL_SERVICE_INTROSPECTION_OFF;
          } else if (param.as_string() == "metadata") {
            introspection_state = RCL_SERVICE_INTROSPECTION_METADATA;
          } else if (param.as_string() == "contents") {
            introspection_state = RCL_SERVICE_INTROSPECTION_CONTENTS;
          }

          this->srv_->configure_introspection(
            this->get_clock(), rclcpp::SystemDefaultsQoS(), introspection_state);
          break;
        }
      };

    on_set_parameters_callback_handle_ = this->add_on_set_parameters_callback(
      on_set_parameter_callback);
    post_set_parameters_callback_handle_ = this->add_post_set_parameters_callback(
      post_set_parameter_callback);

    this->declare_parameter("service_configure_introspection", "disabled");
  }

private:
  rclcpp::Service<example_interfaces::srv::AddTwoInts>::SharedPtr srv_;
  rclcpp::node_interfaces::OnSetParametersCallbackHandle::SharedPtr
    on_set_parameters_callback_handle_;
  rclcpp::node_interfaces::PostSetParametersCallbackHandle::SharedPtr
    post_set_parameters_callback_handle_;
};

}  // namespace demo_nodes_cpp

服务自省默认是禁用的，因此用户需要启用它以在服务服务器上调用“configure_introspection”。 在这个演示中，“IntrospectionServiceNode”使用名为“service_configure_introspection”的参数来配置服务自省状态。

首先我们需要启动“IntrospectionServiceNode”。

$ ros2 run demo_nodes_cpp introspection_service

要改变服务自省状态，我们需要设置“configure_introspection”参数，如下所示。

### User data contents with metadata
$ ros2 param set /introspection_service service_configure_introspection contents
### Or only metadata
$ ros2 param set /introspection_service service_configure_introspection metadata
### To disable
$ ros2 param set /introspection_service service_configure_introspection disabled

自省客户端节点：

https://github.com/ros2/demos/blob/rolling/demo_nodes_cpp/src/services/introspection_client.cpp

namespace demo_nodes_cpp
{
class IntrospectionClientNode : public rclcpp::Node
{
public:
  DEMO_NODES_CPP_PUBLIC
  explicit IntrospectionClientNode(const rclcpp::NodeOptions & options)
  : Node("introspection_client", options)
  {
    client_ = create_client<example_interfaces::srv::AddTwoInts>("add_two_ints");

    auto on_set_parameter_callback =
      [](std::vector<rclcpp::Parameter> parameters) {
        rcl_interfaces::msg::SetParametersResult result;
        result.successful = true;
        for (const rclcpp::Parameter & param : parameters) {
          if (param.get_name() != "client_configure_introspection") {
            continue;
          }

          if (param.get_type() != rclcpp::ParameterType::PARAMETER_STRING) {
            result.successful = false;
            result.reason = "must be a string";
            break;
          }

          if (param.as_string() != "disabled" && param.as_string() != "metadata" &&
            param.as_string() != "contents")
          {
            result.successful = false;
            result.reason = "must be one of 'disabled', 'metadata', or 'contents'";
            break;
          }
        }

        return result;
      };

    auto post_set_parameter_callback =
      [this](const std::vector<rclcpp::Parameter> & parameters) {
        for (const rclcpp::Parameter & param : parameters) {
          if (param.get_name() != "client_configure_introspection") {
            continue;
          }

          rcl_service_introspection_state_t introspection_state = RCL_SERVICE_INTROSPECTION_OFF;

          if (param.as_string() == "disabled") {
            introspection_state = RCL_SERVICE_INTROSPECTION_OFF;
          } else if (param.as_string() == "metadata") {
            introspection_state = RCL_SERVICE_INTROSPECTION_METADATA;
          } else if (param.as_string() == "contents") {
            introspection_state = RCL_SERVICE_INTROSPECTION_CONTENTS;
          }

          this->client_->configure_introspection(
            this->get_clock(), rclcpp::SystemDefaultsQoS(), introspection_state);
          break;
        }
      };

    on_set_parameters_callback_handle_ = this->add_on_set_parameters_callback(
      on_set_parameter_callback);
    post_set_parameters_callback_handle_ = this->add_post_set_parameters_callback(
      post_set_parameter_callback);

    this->declare_parameter("client_configure_introspection", "disabled");

    timer_ = this->create_wall_timer(
      std::chrono::milliseconds(500),
      [this]() {
        if (!client_->service_is_ready()) {
          return;
        }

        if (!request_in_progress_) {
          auto request = std::make_shared<example_interfaces::srv::AddTwoInts::Request>();
          request->a = 2;
          request->b = 3;
          request_in_progress_ = true;
          client_->async_send_request(
            request,
            [this](rclcpp::Client<example_interfaces::srv::AddTwoInts>::SharedFuture cb_f)
            {
              request_in_progress_ = false;
              RCLCPP_INFO(get_logger(), "Result of add_two_ints: %ld", cb_f.get()->sum);
            }
          );
          return;
        }
      });
  }

private:
  rclcpp::Client<example_interfaces::srv::AddTwoInts>::SharedPtr client_;
  rclcpp::TimerBase::SharedPtr timer_;
  rclcpp::node_interfaces::OnSetParametersCallbackHandle::SharedPtr
    on_set_parameters_callback_handle_;
  rclcpp::node_interfaces::PostSetParametersCallbackHandle::SharedPtr
    post_set_parameters_callback_handle_;
  bool request_in_progress_{false};
};

}  // namespace demo_nodes_cpp

然后，我们以同样的方式启动并配置“IntrospectionClientNode”。

$ ros2 run demo_nodes_cpp introspection_client

更改服务自省状态以设置“configure_introspection”参数，如下所示。

### User data contents with metadata
$ ros2 param set /introspection_client client_configure_introspection contents
### Or only metadata
$ ros2 param set /introspection_client client_configure_introspection metadata
### To disable
$ ros2 param set /introspection_client client_configure_introspection disabled

在本教程中，以下是“IntrospectionServiceNode”上的服务自省状态“CONTENTS”和“IntrospectionClientNode”上的服务自省状态“METADATA”的示例输出。 为了监视“IntrospectionClientNode”和“IntrospectionServiceNode”之间的服务通信，让我们运行它：

$ ros2 service echo --flow-style /add_two_ints
info:
  event_type: REQUEST_SENT
  stamp:
    sec: 1709432402
    nanosec: 680094264
  client_gid: [1, 15, 0, 18, 86, 208, 115, 86, 0, 0, 0, 0, 0, 0, 21, 3]
  sequence_number: 247
request: []
response: []
---
info:
  event_type: REQUEST_RECEIVED
  stamp:
    sec: 1709432402
    nanosec: 680459568
  client_gid: [1, 15, 0, 18, 86, 208, 115, 86, 0, 0, 0, 0, 0, 0, 20, 4]
  sequence_number: 247
request: [{a: 2, b: 3}]
response: []
---
info:
  event_type: RESPONSE_SENT
  stamp:
    sec: 1709432402
    nanosec: 680765280
  client_gid: [1, 15, 0, 18, 86, 208, 115, 86, 0, 0, 0, 0, 0, 0, 20, 4]
  sequence_number: 247
request: []
response: [{sum: 5}]
---
info:
  event_type: RESPONSE_RECEIVED
  stamp:
    sec: 1709432402
    nanosec: 681027998
  client_gid: [1, 15, 0, 18, 86, 208, 115, 86, 0, 0, 0, 0, 0, 0, 21, 3]
  sequence_number: 247
request: []
response: []
---
...

您可以看到 event_type: REQUEST_SENT 和 event_type: RESPONSE_RECEIVED，这些自省服务事件发生在 IntrospectionClientNode 中。 并且这些事件不包含 request 和 response 字段中的任何内容，这是因为 IntrospectionClientNode 的服务自省状态设置为 METADATA。 另一方面，来自 IntrospectionServiceNode 的 event_type: REQUEST_RECEIVED 和 event_type: RESPONSE_SENT 事件包含 request: [{a: 2, b: 3}] 和 response: [{sum: 5}]，因为自省状态设置为 CONTENTS。

相关内容

• service introspection client example (rclcpp) and service introspection service example (rclcpp).

• service introspection client and service example (rclpy).

• Service Introspection REP-2012.