socket.io server publish

I have a very simple node server which listens to a socket and transmits the messages to all clients (flex). While this works for clients publishing the message, I want to be able to publish messages also through a web API. Is it possible?

var express = require('express');
var app = express();
var io = require('socket.io').listen(server, {
    flashPolicyServer: true,
    transports: ['flashsocket', 'websocket', 'htmlfile', 'xhr-polling', 'jsonp-polling']});

io.sockets.on('connection', function(client) {
    client.on('invalidation', function(message) {
        client.emit('message', message); // send message to sender
        client.broadcast.emit('message', message); // send message to everyone else but the sender
    });

    client.on('disconnect', function(client) {});
});