How do you pass a callback to emit to express.io.route

[chicheongweng]

With pure socket io, I can pass callback to emit as follows:

server side:
socket.on('data', function(data, callback) {
process data from client;
callback && callback(true);
}

client side:
socket.emit('data', {name:value}, function(data) { console.log('The server got something'); }

But if I use express.io on the server side, the below code does not work because the callback is null.
express.io.route('data', function(req, callback) {
process data from client;
callback && callback(true); <--- This does not work because callback is undefined
}

So how do I do the callback to client side's emit on the server side using expressio?

[woojoo666]

needed this functionality too, trying this:

app.io.route('ready', function (socket) {
    console.log('Client connected');
    socket.io.emit('news', { hello: 'world' });
    socket.io.route('my other event', function (data) {
        console.log(data);
    });
});

gives "undefined is not a function" error