Feature parity review: rclpy-inspired improvements for rclnodejs

[minggangw]

#	Feature	Status	Notes
1	Executor Framework	Skipped	Not needed in rclnodejs. Each Node already has its own background thread via ShadowNode/Executor. Multiple node.spin() calls work independently. Node.js is single-threaded so all JS callbacks are inherently serialized — callback groups are meaningless.
2	Callback Groups	Skipped	Depends on Executor Framework. Node.js single-threaded model means all callbacks are already mutually exclusive by design.
3	waitForMessage() Utility	Implemented	PR #1444. Creates a temporary subscription, resolves on first message, auto-cleans up. Uses TimeoutError for timeout rejection. Extracted to lib/wait_for_message.js.
4	Parameter Event Handler	Implemented	PR #1438. ParameterEventHandler class with per-parameter and event-level callbacks. Refactored ParameterWatcher to use it internally. All Copilot review comments addressed.
5	QoS Overriding via Parameters	Implemented	PR #1468. QoSOverridingOptions class and QoSPolicyKind enum. Declares read-only parameters (e.g. qos_overrides./topic.subscription.depth) for whitelisted QoS policies on createPublisher() / createSubscription(). Overridable at startup via --ros-args -p, launch files, or parameter files. Includes withDefaultPolicies() factory (history, depth, reliability), entity ID disambiguation, and optional validation callback. Matches rclpy's _declare_qos_parameters() behavior.
6	Better spin() API / spinUntilFutureComplete	Dropped	Implemented in PR #1442, then evaluated as syntactic sugar with minimal value. In rclnodejs spin() is non-blocking (unlike rclpy where it blocks), so spin/await/stop is already trivial. Decided to drop in favor of documenting the idiomatic pattern.
7	Signal Handler Guard Condition	Skipped	Not needed. Node.js delivers SIGINT via the libuv event loop to the main thread immediately. The existing process.on('SIGINT') + shutdownAll() mechanism already provides clean, immediate shutdown. The background rcl_wait() thread is woken via StopWaitingHandles(). A guard condition would add complexity without observable benefit.
8	Message Metadata (MessageInfo)	Implemented	PR #1440. Native rclTakeWithInfo binding, MessageInfo class, auto-detection via callback.length >= 2. TypeScript types updated. Copilot review comments addressed.
8	Pre/Post Set Parameter Callbacks	Implemented	PR #1470. addPreSetParametersCallback() / removePreSetParametersCallback() and addPostSetParametersCallback() / removePostSetParametersCallback() on Node. Pre callbacks run before validation and can transform the parameter list; post callbacks run after successful set for side effects. Both LIFO ordered. Matches rclpy's add_pre_set_parameters_callback / add_post_set_parameters_callback.
9	Timer autostart + TimerInfo callback support	Implemented	PR #1472. Latest timer update. Node.createTimer() now accepts { autostart?: boolean } while preserving existing call signatures. Timer callbacks receive TimerInfo when supported, exposing expectedCallTime and actualCallTime. Older distros emulate autostart: false via cancel/reset. Native createTimer also validates that the 4th argument is a boolean. Includes runtime and type test coverage.
10	ParameterEventHandler Node Filtering	Implemented	PR for #1473. configureNodesFilter(nodeNames?) on ParameterEventHandler. Filters /parameter_events subscription by node name using DDS content filters. Resolves relative names against handler node namespace. Validates fully qualified node paths via existing ROS validators. Normalizes repeated/trailing slashes. Includes runtime tests (absolute/relative/clear/invalid/slash-normalization) and tsd type coverage.

[minggangw]

Updated: April 3, 2026

#	Feature	Status	PR / Issue	Notes
1	Executor Framework	Skipped	—	Not needed in rclnodejs. Each Node already has its own background thread via ShadowNode/Executor. Multiple node.spin() calls work independently. Node.js is single-threaded so all JS callbacks are inherently serialized — callback groups are meaningless.
2	Callback Groups	Skipped	—	Depends on Executor Framework. Node.js single-threaded model means all callbacks are already mutually exclusive by design.
2b	EventsExecutor	Skipped	—	Experimental in rclpy; no equivalent value for Node.js.
3	waitForMessage()	Implemented	#1444 / #1443	Creates a temporary subscription, resolves on first message, auto-cleans up. Uses TimeoutError for timeout rejection. Extracted to lib/wait_for_message.js.
4	ParameterEventHandler	Implemented	#1438 / #1437	ParameterEventHandler class with per-parameter and event-level callbacks. Refactored ParameterWatcher to use it internally. All Copilot review comments addressed.
4b	ParameterEventHandler Node Filtering	Implemented	#1473	configureNodesFilter(nodeNames?) applies/clears a /parameter_events subscription content filter for selected nodes. Resolves relative names against handler node namespace. Validates fully qualified node paths via existing ROS validators. Normalizes repeated/trailing slashes. Includes runtime tests (absolute/relative/clear/invalid/slash-normalization) and tsd type coverage.
5	QoS Overriding via Parameters	Implemented	#1468 / #1467	QoSOverridingOptions class and QoSPolicyKind enum. Declares read-only parameters (e.g. qos_overrides./topic.subscription.depth) for whitelisted QoS policies on createPublisher() / createSubscription(). Overridable at startup via --ros-args -p, launch files, or parameter files. Includes withDefaultPolicies() factory (history, depth, reliability), entity ID disambiguation, and optional validation callback. Matches rclpy's _declare_qos_parameters() behavior.
6	spinUntilFutureComplete	Dropped	#1441	Implemented in PR #1442, then evaluated as syntactic sugar with minimal value. In rclnodejs spin() is non-blocking (unlike rclpy where it blocks), so spin/await/stop is already trivial. Decided to drop in favor of documenting the idiomatic pattern.
7	Signal Handler Guard Condition	Skipped	—	Not needed. Node.js delivers SIGINT via the libuv event loop to the main thread immediately. The existing process.on('SIGINT') + shutdownAll() mechanism already provides clean, immediate shutdown. The background rcl_wait() thread is woken via StopWaitingHandles(). A guard condition would add complexity without observable benefit.
8	MessageInfo Metadata	Implemented	#1440 / #1439	Native rclTakeWithInfo binding, MessageInfo class, auto-detection via callback.length >= 2. TypeScript types updated. Copilot review comments addressed.
9	Pre/Post Set Parameter Callbacks	Implemented	#1470 / #1469	addPreSetParametersCallback() / removePreSetParametersCallback() and addPostSetParametersCallback() / removePostSetParametersCallback() on Node. Pre callbacks run before validation and can transform the parameter list; post callbacks run after successful set for side effects. Both LIFO ordered. Matches rclpy's add_pre_set_parameters_callback / add_post_set_parameters_callback.
10	Timer autostart + TimerInfo	Implemented	#1472 / #1471	Node.createTimer() now accepts { autostart?: boolean } while preserving existing call signatures. Timer callbacks receive TimerInfo when supported, exposing expectedCallTime and actualCallTime. Older distros emulate autostart: false via cancel/reset. Native createTimer also validates that the 4th argument is a boolean. Includes runtime and type test coverage.
11	Action Server Goal State Guards	Implemented	#1466	publishFeedback only in EXECUTING, execute guards.
12	Action Client Feedback Content Filter	Implemented	#1457	Rolling-only native bindings, executor synchronization.
13	TopicEndpointInfo Type Hash	Existing	—	topic_type_hash is already exposed in graph APIs and consumed by TypeDescriptionService. No new work needed.
14	GPU Buffer Backends	Skipped	—	No JS GPU memory interop (acceptable_buffer_backends).
15	Node enable_logger_service	Remaining	—	Low impact (debugging only), medium effort.
16	Waitables	Remaining	—	Low impact (advanced extensibility), high effort.
17	SyncParameterClient	Remaining (Skip)	—	Async is idiomatic in JS; low value.

Summary

• Implemented: 10 features
• Existing (already covered): 1
• Skipped (N/A for Node.js): 5
• Dropped (low value): 1
• Remaining (low priority): 3

Unique to rclnodejs

• ObservableSubscription (RxJS)
• Message validation (validateMessage(), schemas)
• Serialization modes ('default', 'plain', 'json')
• Message introspection (MessageIntrospector, getMessageSchema())
• Process launching (ros2Run(), ros2Launch())
• JSON-safe conversion (toJSONSafe(), toJSONString())
• ParameterWatcher (EventEmitter-based remote param watcher)