function as parameter in node.js module

in this code: if i try to pass this.handler as parameter to server.createServer() , then i get no response (the page keeps loading in browser). but if i use server.createServer(function(req, res) { //same code here as in handler() }) , then it works. what am i doing wrong?

var Con = module.exports = function() {
    process.EventEmitter.call(this);
} 

var createServer = module.exports.createServer = function(options) {
    console.log('start');
    this.port = options.port || 9122;
    this.secure = options.secure || false;
    if(this.secure === true)
        if(!options.key || !options.certificate)
            this.secure = false;
        else {
            this.key = options.key;
            this.certificate = options.certificate;
        }

    if(this.secure) {
        this.server = require('https');
        var fs = require('fs');
        var opt = {
            key: fs.readFileSync('privatekey.pem'),
            cert: fs.readFileSync('certificate.pem')
        };
        this.server.createServer(opt, this.handler).listen(this.port); 
    } else {
        this.server = require('http');
        this.server.createServer(this.handler).listen(this.port);
    } 
}

Con.prototype.handler = function(req, res) {
    console.log('request');
    res.writeHead(200);
    res.write(req.url);
    res.end();   
}