BroadcastChannel doesn't fill in useful MessageEvent fields like source, or ports

Please populate the Worker value in BroadcastChannel MessageEvents 'source' field the same way it is in WebWorkers.

There is currently no mechanism to compose Workers in the NodeJS APIs and this change would provide a mechanism to
solve that problem, if not for the general case, at least with only a small amount of additional bookkeeping on the part of
application developers.

Without a composition mechanism, it is extremely difficult to implement cross-cutting concerns between workers, and between workers and large subsystems in the main application. Which is problematic for many areas of production code including caching, telemetry, reloadable configuration, and security.

Fundamentally, there is no mechanism to tell if a Worker has terminated. And since Workers tend to be used for tasks with high utilization of the event toop, even sending a message to ask if anyone is still listening to the BroadcastChannel is not guaranteed to work on any reasonable time frame, and in particular for cross-cutting concerns who can't know what, for instance, the cutoff time is for image processing in the Image Worker, and that the Cache Worker has a cutoff of 1/100th of that time. Which then leads to a scenario where you've decided a Worker is dead and then the same worker pops back up 10 seconds later. What you need is worker.on('exit') which is unambiguous.

Version

All versions

Platform

All Platforms

Subsystem

node:worker_threads

What steps will reproduce the bug?

        const util = require('util');
	const channel = new BroadcastChannel('example');

	if (isMainThread) {
		channel.addEventListener('message', evt => {
			console.log(util.inspect(evt)); // breakpoint here
		});
	} else {
		channel.postMessage('hello');
        }

The Message Event recieved looks like

MessageEvent {
  type: 'message',
  defaultPrevented: false,
  cancelable: false,
  timeStamp: 444.018666
}

How often does it reproduce? Is there a required condition?

Always. Seems to be by design, and the design may have drifted from the current web standards over time.

What is the expected behavior? Why is that the expected behavior?

That I get a Worker object to facilitate lifecycle management and IPC coordination.

What do you see instead?

empty string, empty array. And no other mechanism in the Node API to interrogate the running isolates to find this information.

Additional information

No response

Commencez au point d’entrée node:worker_threads BroadcastChannel et reproduisez la sortie de MessageEvent de l’exemple fourni. Comparez ses champs source et ports avec le comportement de WebWorkers décrit dans l’issue, puis vérifiez que l’événement résultant expose les informations Worker demandées et le comportement de coordination du cycle de vie.