Processing external triggers in Node.js applications

Question

I have a Node.js daemon application that runs on my Debian home server 24/7.

I would like it to process triggers generated by motion, a program that monitors the video signal from cameras that is installed on the same machine. Motion can execute a command on certain events, for example when motion was detected, or camera connection was lost.

I can write a script that will process these events and record them in the database and in my daemon I can continuously poll the database. But that would be highly inefficient, right?

What would be the optimal way to process external triggers in Node.js applications?

Answer 1

Have a look at dnode. It allows you to do exactly what you are looking for.

In your daemon you will have something like this.

var dnode = require('dnode');
var server = dnode({
    transform : function (eventObject, cb) {
        //handle the event

        cb(callbackDataHere)
    }
});
server.listen(5004);

You will then need to create the command that Motion will call

var dnode = require('dnode');

var d = dnode.connect(5004);
d.on('remote', function (remote) {

    var eventDataToSend = {}

    remote.transform(eventDataToSend, function (s) {
        //Do stuff with arguments sent back from the callback on the server
    });
});