introduce ActionEndpointInfo from action graph.

rclcpp_action/CMakeLists.txt

@@ -23,6 +23,7 @@ add_library(${PROJECT_NAME}
   src/create_generic_client.cpp
   src/generic_client.cpp
   src/generic_client_goal_handle.cpp
+  src/graph.cpp
   src/qos.cpp
   src/server.cpp
   src/server_goal_handle.cpp
@@ -109,6 +110,17 @@ if(BUILD_TESTING)
     )
   endif()
 
+  ament_add_gtest(test_graph test/test_graph.cpp TIMEOUT 180)
+  if(TARGET test_graph)
+    target_link_libraries(test_graph
+      ${PROJECT_NAME}
+      rcl::rcl
+      rcl_action::rcl_action
+      rclcpp::rclcpp
+      test_msgs::test_msgs
+    )
+  endif()
+
   ament_add_gtest(test_server test/test_server.cpp TIMEOUT 180)
   ament_add_test_label(test_server mimick)
   if(TARGET test_server)

rclcpp_action/include/rclcpp_action/graph.hpp

@@ -0,0 +1,234 @@
+// Copyright 2026 TriOrb, Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#ifndef RCLCPP_ACTION__GRAPH_HPP_
+#define RCLCPP_ACTION__GRAPH_HPP_
+
+#include <optional>
+#include <string>
+#include <vector>
+
+#include "rcl_action/graph.h"
+
+#include "rclcpp/node_interfaces/node_base_interface.hpp"
+#include "rclcpp/node_interfaces/node_graph_interface.hpp"
+
+#include "rclcpp_action/visibility_control.hpp"
+
+namespace rclcpp_action
+{
+
+/// Endpoint information of an action client or an action server.
+/**
+ * An action is built on top of three services and two topics:
+ *
+ * - the goal service (`<action_name>/_action/send_goal`)
+ * - the cancel service (`<action_name>/_action/cancel_goal`)
+ * - the result service (`<action_name>/_action/get_result`)
+ * - the feedback topic (`<action_name>/_action/feedback`)
+ * - the status topic (`<action_name>/_action/status`)
+ *
+ * This class aggregates the endpoint information of all the underlying
+ * entities of one action client or one action server.
+ * The goal service endpoint is used as the canonical identity of an action
+ * client or an action server, so the goal service endpoint information is
+ * always populated and the node name, node namespace, action type, and
+ * endpoint type are derived from it.
+ * The remaining endpoint information is correlated to the goal service
+ * endpoint by the node name and node namespace, and is `std::nullopt` if the
+ * underlying entity has not been discovered.
+ */
+class ActionEndpointInfo
+{
+public:
+  /// Construct from a rcl_action_endpoint_info_t.
+  /**
+   * \param[in] info the rcl endpoint information to construct from, its
+   *   `goal_service_info` member must be populated.
+   * \throws std::invalid_argument if the goal service info is not populated.
+   */
+  RCLCPP_ACTION_PUBLIC
+  explicit ActionEndpointInfo(const rcl_action_endpoint_info_t & info);
+
+  /// Get the node name of the action endpoint.
+  RCLCPP_ACTION_PUBLIC
+  const std::string &
+  node_name() const;
+
+  /// Get the node namespace of the action endpoint.
+  RCLCPP_ACTION_PUBLIC
+  const std::string &
+  node_namespace() const;
+
+  /// Get the action type, derived from the goal service type.
+  RCLCPP_ACTION_PUBLIC
+  std::string
+  action_type() const;
+
+  /// Get the endpoint type (client or server) of the action endpoint.
+  RCLCPP_ACTION_PUBLIC
+  rclcpp::EndpointType
+  endpoint_type() const;
+
+  /// Get a mutable reference to the endpoint information of the goal service.
+  RCLCPP_ACTION_PUBLIC
+  rclcpp::ServiceEndpointInfo &
+  goal_service_info();
+
+  /// Get a const reference to the endpoint information of the goal service.
+  RCLCPP_ACTION_PUBLIC
+  const rclcpp::ServiceEndpointInfo &
+  goal_service_info() const;
+
+  /// Get a mutable reference to the endpoint information of the cancel service.
+  RCLCPP_ACTION_PUBLIC
+  std::optional<rclcpp::ServiceEndpointInfo> &
+  cancel_service_info();
+
+  /// Get a const reference to the endpoint information of the cancel service.
+  RCLCPP_ACTION_PUBLIC
+  const std::optional<rclcpp::ServiceEndpointInfo> &
+  cancel_service_info() const;
+
+  /// Get a mutable reference to the endpoint information of the result service.
+  RCLCPP_ACTION_PUBLIC
+  std::optional<rclcpp::ServiceEndpointInfo> &
+  result_service_info();
+
+  /// Get a const reference to the endpoint information of the result service.
+  RCLCPP_ACTION_PUBLIC
+  const std::optional<rclcpp::ServiceEndpointInfo> &
+  result_service_info() const;
+
+  /// Get a mutable reference to the endpoint information of the feedback topic.
+  RCLCPP_ACTION_PUBLIC
+  std::optional<rclcpp::TopicEndpointInfo> &
+  feedback_topic_info();
+
+  /// Get a const reference to the endpoint information of the feedback topic.
+  RCLCPP_ACTION_PUBLIC
+  const std::optional<rclcpp::TopicEndpointInfo> &
+  feedback_topic_info() const;
+
+  /// Get a mutable reference to the endpoint information of the status topic.
+  RCLCPP_ACTION_PUBLIC
+  std::optional<rclcpp::TopicEndpointInfo> &
+  status_topic_info();
+
+  /// Get a const reference to the endpoint information of the status topic.
+  RCLCPP_ACTION_PUBLIC
+  const std::optional<rclcpp::TopicEndpointInfo> &
+  status_topic_info() const;
+
+private:
+  rclcpp::ServiceEndpointInfo goal_service_info_;
+  std::optional<rclcpp::ServiceEndpointInfo> cancel_service_info_;
+  std::optional<rclcpp::ServiceEndpointInfo> result_service_info_;
+  std::optional<rclcpp::TopicEndpointInfo> feedback_topic_info_;
+  std::optional<rclcpp::TopicEndpointInfo> status_topic_info_;
+};
+
+/// Return a list of action clients on a given action.
+/**
+ * The returned parameter is a list of ActionEndpointInfo objects, where each
+ * aggregates the endpoint information of all the underlying entities of one
+ * action client, i.e. the clients of the goal, cancel, and result services
+ * and the subscriptions on the feedback and status topics.
+ *
+ * The `action_name` may be a relative, private, or fully qualified action
+ * name.
+ * A relative or private action name will be expanded using the node's
+ * namespace and name.
+ * The queried `action_name` is not remapped.
+ *
+ * \param[in] node_base the node base interface of the node used to query the ROS graph.
+ * \param[in] action_name name of the action to query.
+ * \return a list of ActionEndpointInfo representing all the action clients on this action.
+ * \throws std::invalid_argument if the action name is invalid.
+ * \throws std::runtime_error if the list cannot be retrieved.
+ */
+RCLCPP_ACTION_PUBLIC
+std::vector<ActionEndpointInfo>
+get_action_clients_info_by_action(
+  const rclcpp::node_interfaces::NodeBaseInterface::SharedPtr & node_base,
+  const std::string & action_name);
+
+/// Return a list of action servers on a given action.
+/**
+ * The returned parameter is a list of ActionEndpointInfo objects, where each
+ * aggregates the endpoint information of all the underlying entities of one
+ * action server, i.e. the servers of the goal, cancel, and result services
+ * and the publishers on the feedback and status topics.
+ *
+ * The `action_name` may be a relative, private, or fully qualified action
+ * name.
+ * A relative or private action name will be expanded using the node's
+ * namespace and name.
+ * The queried `action_name` is not remapped.
+ *
+ * \param[in] node_base the node base interface of the node used to query the ROS graph.
+ * \param[in] action_name name of the action to query.
+ * \return a list of ActionEndpointInfo representing all the action servers on this action.
+ * \throws std::invalid_argument if the action name is invalid.
+ * \throws std::runtime_error if the list cannot be retrieved.
+ */
+RCLCPP_ACTION_PUBLIC
+std::vector<ActionEndpointInfo>
+get_action_servers_info_by_action(
+  const rclcpp::node_interfaces::NodeBaseInterface::SharedPtr & node_base,
+  const std::string & action_name);
+
+/// Return the number of action clients on a given action.
+/**
+ * The `action_name` may be a relative, private, or fully qualified action
+ * name.
+ * A relative or private action name will be expanded using the node's
+ * namespace and name.
+ * The queried `action_name` is not remapped.
+ *
+ * \param[in] node_base the node base interface of the node used to query the ROS graph.
+ * \param[in] action_name name of the action to count the number of action clients.
+ * \return the number of action clients on the action.
+ * \throws std::invalid_argument if the action name is invalid.
+ * \throws std::runtime_error if the count cannot be retrieved.
+ */
+RCLCPP_ACTION_PUBLIC
+size_t
+count_action_clients(
+  const rclcpp::node_interfaces::NodeBaseInterface::SharedPtr & node_base,
+  const std::string & action_name);
+
+/// Return the number of action servers on a given action.
+/**
+ * The `action_name` may be a relative, private, or fully qualified action
+ * name.
+ * A relative or private action name will be expanded using the node's
+ * namespace and name.
+ * The queried `action_name` is not remapped.
+ *
+ * \param[in] node_base the node base interface of the node used to query the ROS graph.
+ * \param[in] action_name name of the action to count the number of action servers.
+ * \return the number of action servers on the action.
+ * \throws std::invalid_argument if the action name is invalid.
+ * \throws std::runtime_error if the count cannot be retrieved.
+ */
+RCLCPP_ACTION_PUBLIC
+size_t
+count_action_servers(
+  const rclcpp::node_interfaces::NodeBaseInterface::SharedPtr & node_base,
+  const std::string & action_name);
+
+}  // namespace rclcpp_action
+
+#endif  // RCLCPP_ACTION__GRAPH_HPP_

rclcpp_action/include/rclcpp_action/rclcpp_action.hpp

@@ -37,6 +37,7 @@
 #include "rclcpp_action/client_goal_handle.hpp"
 #include "rclcpp_action/create_client.hpp"
 #include "rclcpp_action/create_server.hpp"
+#include "rclcpp_action/graph.hpp"
 #include "rclcpp_action/server.hpp"
 #include "rclcpp_action/server_goal_handle.hpp"
 #include "rclcpp_action/visibility_control.hpp"