Trait ActionClient

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pub trait ActionClient<G, F, R>where
    G: Send + 'static,
    F: Send + 'static,
    R: Send + 'static,{
    // Required methods
    fn action_name(&self) -> &str;
    fn schema(&self) -> &ActionSchema;
    fn send_goal(&mut self, goal: G) -> Result<(ActionGoalId, GoalAck), RtError>;
    fn poll_feedback(
        &mut self,
        goal_id: ActionGoalId,
    ) -> Option<ActionFeedback<F>>;
    fn poll_result(&mut self, goal_id: ActionGoalId) -> Option<ActionResult<R>>;
    fn cancel(&mut self, goal_id: ActionGoalId) -> Result<(), RtError>;
    fn goal_status(&self, goal_id: ActionGoalId) -> Option<GoalStatus>;
    fn close(&mut self) -> Result<(), RtError>;

    // Provided methods
    fn tick_timeouts(&mut self, _now: Timestamp) -> usize { ... }
    fn goal_health(&self, _goal_id: ActionGoalId) -> Option<ActionSessionHealth> { ... }
    fn active_goal_health(&self) -> Vec<ActionSessionHealth> { ... }
}

Expand description

Client-side handle: sends goals, polls feedback, and retrieves the final result.

§Comparison with Service and Mission

Feature	Service	Action	Mission
Direction	req → res	goal → feedback* → result	long-lived duplex
Streaming	✗	✓ (best-effort)	✓ (reliable)
Cancel	✗	✓	✓ (Pause/Cancel)
Reconnect	✗	✗	✓ (Reconcile)
State-machine	none	simple (6 states)	complex (8 states)

Required Methods§

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fn action_name(&self) -> &str

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fn schema(&self) -> &ActionSchema

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fn send_goal(&mut self, goal: G) -> Result<(ActionGoalId, GoalAck), RtError>

Send a goal and immediately receive the server’s accept/reject acknowledgement.

The returned ActionGoalId is used for subsequent poll_feedback, poll_result, and cancel calls. If the server rejects the goal (GoalAck::accepted == false), the ID remains valid but no feedback or result will ever be produced for it.

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fn poll_feedback(&mut self, goal_id: ActionGoalId) -> Option<ActionFeedback<F>>

Non-blocking poll: dequeue the next feedback item for the given goal, or None if empty.

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fn poll_result(&mut self, goal_id: ActionGoalId) -> Option<ActionResult<R>>

Non-blocking poll: take the final result for the given goal, or None if not ready.

Once Some is returned the goal’s lifecycle is over; the ID need not be tracked further.

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fn cancel(&mut self, goal_id: ActionGoalId) -> Result<(), RtError>

Request cancellation of a goal.

Cancellation is a request, not a command; the server may refuse (e.g. the goal has entered a critical phase). On success, poll_result will eventually return GoalStatus::Canceled.

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