Some code that shows how to implement background execution in Node running on Windows Azure (or iisnode generally).

server.js

var status = {
    started: Date.now(),
    heartbeat: Date.now(),
    runtime: null
};

var heartbeater = function() {
    status.heartbeat = Date.now();
    status.runtime = status.heartbeat - status.started;
    setTimeout(heartbeater, 1000);
};
setTimeout(heartbeater, 1000);

var http = require('http')
var port = process.env.PORT || 1337;

http.createServer(function (req, res) {
    res.writeHead(200, { 'Content-Type': 'application/json' });
    var statusJSON = JSON.stringify(status);
    res.end(statusJSON);
}).listen(port);