rclcpp: ROS Client Library for C++

rclcpp provides the canonical C++ API for interacting with ROS. It consists of these main components:

• Nodes
  • rclcpp::node::Node
  • rclcpp/node.hpp
• Publisher
  • rclcpp::node::Node::create_publisher()
  • rclcpp::publisher::Publisher
  • rclcpp::publisher::Publisher::publish()
  • rclcpp/publisher.hpp
• Subscription
  • rclcpp::node::Node::create_subscription()
  • rclcpp::subscription::Subscription
  • rclcpp/subscription.hpp
• Service Client
  • rclcpp::node::Node::create_client()
  • rclcpp::client::Client
  • rclcpp/client.hpp
• Service Server
  • rclcpp::node::Node::create_service()
  • rclcpp::service::Service
  • rclcpp/service.hpp
• Timer
  • rclcpp::node::Node::create_wall_timer()
  • rclcpp::timer::WallTimer
  • rclcpp::timer::TimerBase
  • rclcpp/timer.hpp
• Parameters:
  • rclcpp::node::Node::set_parameters()
  • rclcpp::node::Node::get_parameters()
  • rclcpp::node::Node::get_parameter()
  • rclcpp::node::Node::describe_parameters()
  • rclcpp::node::Node::list_parameters()
  • rclcpp::node::Node::register_param_change_callback()
  • rclcpp::parameter::ParameterVariant
  • rclcpp::parameter_client::AsyncParametersClient
  • rclcpp::parameter_client::SyncParametersClient
  • rclcpp/parameter.hpp
  • rclcpp/parameter_client.hpp
  • rclcpp/parameter_service.hpp
• Rate:
  • rclcpp::rate::Rate
  • rclcpp::rate::WallRate
  • rclcpp/rate.hpp

There are also some components which help control the execution of callbacks:

• Executors (responsible for execution of callbacks through a blocking spin):
  • rclcpp::spin()
  • rclcpp::spin_some()
  • rclcpp::spin_until_future_complete()
  • rclcpp::executors::single_threaded_executor::SingleThreadedExecutor
  • rclcpp::executors::single_threaded_executor::SingleThreadedExecutor::add_node()
  • rclcpp::executors::single_threaded_executor::SingleThreadedExecutor::spin()
  • rclcpp::executors::multi_threaded_executor::MultiThreadedExecutor
  • rclcpp::executors::multi_threaded_executor::MultiThreadedExecutor::add_node()
  • rclcpp::executors::multi_threaded_executor::MultiThreadedExecutor::spin()
  • rclcpp/executor.hpp
  • rclcpp/executors.hpp
  • rclcpp/executors/single_threaded_executor.hpp
  • rclcpp/executors/multi_threaded_executor.hpp
• CallbackGroups (mechanism for enforcing concurrency rules for callbacks):
  • rclcpp::node::Node::create_callback_group()
  • rclcpp::callback_group::CallbackGroup
  • rclcpp/callback_group.hpp

Additionally, there are some methods for introspecting the ROS graph:

• Graph Events (a waitable event object that wakes up when the graph changes):
  • rclcpp::node::Node::get_graph_event()
  • rclcpp::node::Node::wait_for_graph_change()
  • rclcpp::event::Event
• List topic names and types:
  • rclcpp::node::Node::get_topic_names_and_types()
• Get the number of publishers or subscribers on a topic:
  • rclcpp::node::Node::count_publishers()
  • rclcpp::node::Node::count_subscribers()

Finally, there are many internal API's and utilities:

• Exceptions:
  • rclcpp/exceptions.hpp
• Allocator related items:
  • rclcpp/allocator/allocator_common.hpp
  • rclcpp/allocator/allocator_deleter.hpp
• Memory management tools:
  • rclcpp/memory_strategies.hpp
  • rclcpp/memory_strategy.hpp
  • rclcpp/message_memory_strategy.hpp
  • rclcpp/strategies/allocator_memory_strategy.hpp
  • rclcpp/strategies/message_pool_memory_strategy.hpp
• Context object which is shared amongst multiple Nodes:
  • rclcpp::context::Context
  • rclcpp/context.hpp
  • rclcpp/contexts/default_context.hpp
• Various utilities:
  • rclcpp/function_traits.hpp
  • rclcpp/macros.hpp
  • rclcpp/scope_exit.hpp
  • rclcpp/time.hpp
  • rclcpp/utilities.hpp
  • rclcpp/visibility_control.hpp