Nodejs, keep socket io connection alive in MongoStore

Nodejs, keep socket io connection alive in MongoStore

In a nodejs-express app, in the server.js file I set the socket-io
connection. It works fine doing something like this
var server = require('http').createServer(app)
var io = require('socket.io').listen(server);
io.sockets.on('connection', function (socket) {
// how can I save globally this 'socket'?
});
I would like to save this 'socket' globally in the server.js file and so,
be able to use it everywhere in the project. Like this:
app.get('/on', function(req, res){
socket.on('test', function (data) {
console.log(data);
});
});
app.get('/emit', function(req, res){
socket.emit('test', "ciao");
});
I red there is a way to do it saving the 'socket' connection in session.
My sessions settings:
app.configure(function(){
// ....
app.use(express.cookieParser(SITE_SECRET));
app.use(express.session({
secret :
,store : new MongoStore({
mongoose_connection : mongoose.connection
,db: mongoose.connections[0].db
})
,cookie: { maxAge: new Date(Date.now() + (1000*60*60*24*30*12)) }
}));
...
});
What is a good way to do it?