EventSource demo code

app-client.js

$.ready(function() {
  var source = new EventSource("/events");
  source.addEventListener('data', function(e) {
    $("#content").append(e.data + "\n");
  }, false);
});

app-server.js

var express = require('express');
var fs = require('fs');

// change this to some other log file that doesn't require root permissions to read :)
var logfile = '/var/log/messages';

var app = module.exports = express();

app.use(express.bodyParser());
app.use(express.methodOverride());
app.use(express.static(__dirname + '/public'));

app.use(function(err, req, res, next) {
    console.log('error: ' + err );
});

app.configure('development', function(){
  app.use(express.errorHandler({ dumpExceptions: true, showStack: true }));
});

app.configure('production', function(){
  app.use(express.errorHandler());
});

app.get('/', function(req, res) { res.redirect('/index.html') });

app.get('/events', function(req, res) {
    res.writeHead(200, {
        'Content-Type': 'text/event-stream',
        'Connection': 'keep-alive',
        'Cache-Control': 'no-cache',
    });

    fs.open(logfile, 'r', function(err, fd) {
        // Whenever new data is available to read, send it to the client
        fs.watchFile(logfile, function(curr, prev) {
            if (curr.size > prev.size) {
                console.log("size: %d -> %d", prev.size, curr.size);
                var size = curr.size - prev.size;
                var data = new Buffer(size);
                fs.read(fd, data, 0, size, prev.size, function(err, bytesRead, buffer) {
                    console.log("sending data over eventsource...");
                    res.write("data: "
                        + JSON.stringify({Body: buffer.toString('utf8')})
                        + "\n\n"
                    );
                });
            }
        });

        // If the client disconnects, let's not leak any resources
        res.on('close', function() {
            fs.unwatchFile(logfile);
            fs.close(fd);
        });
    });
});

var http = require('http');
var server = http.createServer(app);
server.listen(process.env.PORT || 3000);
console.log("tailpipe listening on port %d in %s mode", server.address().port, app.settings.env);