如何在我的Web应用程序中创建MVC4中的facebook等通知框？

Question

每次重新加载此页面时，新连接都会开始，当我更新数据库数据时通知.client.updateNotifications = function（）{             警报（＆＃34; 3＆＃34）;             getAllNotifications（）};

多次调用

。否则它工作正常

<script src="/Scripts/jquery.signalR-2.2.0.js"></script>
<!--Reference the autogenerated SignalR hub script. -->
<script src="/signalr/hubs"></script>


<script type="text/javascript">

    var ConnectionStarted = false;
    $(function () {
        alert("1");
        // Declare a proxy to reference the hub.
        var notifications = $.connection.notificationHub;

        //debugger;
        // Create a function that the hub can call to broadcast messages.
        notifications.client.updateNotifications = function () {
            alert("3");
            getAllNotifications()

        };



        $.connection.hub.start().done(function () {
            ConnectionStarted = true;

            alert("2");
            alert("connection started")
            getAllNotifications();
        }).fail(function (e) {
            alert(e);
        });

    });


    function getAllNotifications() {

        var tbl = $('#messagesTable');
        $.ajax({
            url: '/Home/GetNotifications',
            contentType: 'application/html ; charset:utf-8',
            type: 'GET',
            dataType: 'html'
        }).success(function (result) {
            tbl.empty().append(result);
        }).error(function () {

        });
    }
</script>