I'm wondering (since there's no mention of this in the official documentation) if there's a way to emit events from the worker processes which have a different event name from the default, which is message, so that I can set up listeners in the master process something along the lines of:
worker.once('someOtherMsgName', fn)
This is so that I can avoid conditions in the actual callback function and only match the listeners to execute the callback for appropriate messages by their message name?
No
"message" means - you have got new incoming message received by IPC (inter process communication). NodeJS has only one build-in way to send messages between process - process.send and child_process.send
Yes
Of course you can use third party modules (node-ipc for example) or make node to interpret message contents in any way you want:
main.js
const childProcess = require('child_process');
const fork = childProcess.fork(__dirname + '/fork.js');
const initIPC = require('./init-ipc');
initIPC(process);
fork.on('hello', event => {
console.log(event.hello);
});
// Say hello to forked process
fork.send({event: 'hello', hello: 'Hello from main process!'});
fork.js
const initIPC = require('./init-ipc');
initIPC(process);
process.on('hello', event => {
console.log(event.hello);
});
// Say hello to main process
process.send({event: 'hello', hello: 'Hello from forked process!'});
init-ipc.js
exports.initIPC = function (process) {
process.on('message', message => {
if (('event' in message) && typeof message.event === 'string') {
process.emit(message.event, message);
}
});
};