var validation = new Class({
    initialize: function() {
        this.messages = [];
    },
    validate: function() {
        this.messages = [];
        $('summary').innerHTML = '';
        if ($('username').value == '') {
            this.messages.push('You must enter a user name');
        }
        if ($('password').value == '') {
            this.messages.push('You must enter a password');
        }
        if (this.messages.length > 0) {
            var alerts = '';
            this.messages.each(function(item, index) {
                alerts += item + '<br/>';
            });
            $('summary').innerHTML = alerts + '<br/>';
            return false;
        }
        return true;
    }
});