A managed (lifecycle) node implementing the ROS 2 Managed Node design.

A Rclex.LifecycleNode wraps a regular Rclex node and adds the four primary states (:unconfigured, :inactive, :active, :finalized) with the corresponding transitions. The five standard lifecycle services are exposed under the node's namespace:

• ~/change_state (lifecycle_msgs/srv/ChangeState)
• ~/get_state (lifecycle_msgs/srv/GetState)
• ~/get_available_states (lifecycle_msgs/srv/GetAvailableStates)
• ~/get_available_transitions (lifecycle_msgs/srv/GetAvailableTransitions)
• ~/get_transition_graph (lifecycle_msgs/srv/GetAvailableTransitions)

Usage

defmodule MyNode do
  use Rclex.LifecycleNode

  @impl true
  def on_configure(_state) do
    # acquire resources...
    {:ok, %{}}
  end

  @impl true
  def on_activate(_state) do
    # start publishing, etc.
    {:ok, %{}}
  end
end

Rclex.start_lifecycle_node(MyNode, "managed_node", namespace: "/example")
Rclex.lifecycle_change_state("managed_node", :configure, namespace: "/example")
Rclex.lifecycle_change_state("managed_node", :activate, namespace: "/example")

Callbacks

All callbacks are optional and default to {:ok, user_state}. Each receives the current user_state/0 and may return:

• {:ok, new_user_state} — transition succeeds
• {:error, new_user_state} — transition fails (rolls back to the previous primary state)
• {:fatal, new_user_state} — transition errors; goes to :finalized

Available callbacks:

• on_configure/1
• on_cleanup/1
• on_activate/1
• on_deactivate/1
• on_shutdown/1
• on_error/1