想象一下使用SignalR与服务器通信的基于Web的聊天客户端.客户端连接时,其端点信息存储在Azure表中.

聊天客户端可以通过SignalR向另一个聊天客户端发送消息,SignalR查找感兴趣的目标客户端的终点(可能在不同的实例上),然后使用Web API通过SignalR将消息发送到客户端的另一个实例.

为了证明我有uploaded a sample application to github.

当存在单个Azure实例时,这一切都有效.但是,如果存在MULTIPLE azure实例,则从服务器到客户端的SignalR的最终调用将无效.它就像动态代码不存在或者它从“坏”线程中消失或消息以某种方式被发送到错误的实例或者我刚刚犯了一个蠢的错误.

任何想法将不胜感激.

网页设置为此

<input type="radio" name='ClientId' value='A' style='width:30px'/>Chat client A</br>
<input type="radio" name='ClientId' value='B' style='width:30px'/>Chat client B</br>
<input type='button' id='register' value='Register' />
<input type='text' id='txtMessage' size='50' /><input type='button' id='send' value='Send' />

<div id='history'>
</div>

和JS是

<script type="text/javascript">
    $(function () {

        // Declare a proxy to reference the hub. 
        var chat = $.connection.chatHub;

        chat.client.sendMessageToClient = function (message) {
            $('#history').append("<br/>" + message);
        };


        // Start the connection.
        $.connection.hub.start().done(function () {

            $('#register').click(function () {

                // Call the Send method on the hub. 
                chat.server.register($('input[name=ClientId]:checked','#myForm').val());

            });


            $('#send').click(function () {

                // Call the Send method on the hub. 
                chat.server.sendMessageToServer($('input[name=ClientId]:checked','#myForm').val(),$('#txtMessage').val());
            });

        });
    });
</script>

枢纽如下. (我有一个小存储类来存储Azure表中的端点信息).请注意静态方法SendMessageToClient.这是最终失败的.它是从Web Api类调用的(下面)

public class ChatHub : Hub
{
    public void Register(string chatClientId)
    {
        Storage.RegisterChatEndPoint(chatClientId,this.Context.ConnectionId);
    }

    /// <summary>
    /// Receives the message and sends it to the SignalR client.
    /// </summary>
    /// <param name="message">The message.</param>
    /// <param name="connectionId">The connection id.</param>
    public static void SendMessageToClient(string message,string connectionId)
    {
        GlobalHost.ConnectionManager.GetHubContext<ChatHub>().Clients.Client(connectionId).SendMessageToClient(message);

        Debug.WriteLine("Sending a message to the client on SignalR connection id: " + connectionId);
        Debug.WriteLine("Via the Web Api end point: " + RoleEnvironment.CurrentRoleInstance.InstanceEndpoints["WebApi"].IPEndpoint.ToString());

    }


    /// <summary>
    /// Sends the message to other instance.
    /// </summary>
    /// <param name="chatClientId">The chat client id.</param>
    /// <param name="message">The message.</param>
    public void SendMessageToServer(string chatClientId,string message)
    {
        // Get the chatClientId of the destination.
        string otherChatClient = (chatClientId == "A" ? "B" : "A");

        // Find out this other chatClientId's end point
        ChatClientEntity chatClientEntity = Storage.GetChatClientEndpoint(otherChatClient);

        if (chatClientEntity != null)
            ChatWebApiController.SendMessage(chatClientEntity.WebRoleEndPoint,chatClientEntity.SignalRConnectionId,message);
    }
}

最后,ChateWebApiController就是这样

public class ChatWebApiController : ApiController
{
    [HttpGet]
    public void SendMessage(string message,string connectionId)
    {
        //return message;
        ChatHub.SendMessageToClient(message,connectionId);
    }

    /// <summary>
    /// This calls the method above but on a different instance via Web API
    /// </summary>
    /// <param name="endPoint">The end point.</param>
    /// <param name="connectionId">The connection id.</param>
    /// <param name="message">The message.</param>
    public static void SendMessage(string endPoint,string connectionId,string message)
    {
        HttpClient client = new HttpClient();
        client.BaseAddress = new Uri("http://" + endPoint);

        // Add an Accept header for JSON format.
        client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));

        string url = "http://" + endPoint + "/api/ChatWebApi/SendMessage/?Message=" + HttpUtility.UrlEncode(message) + "&ConnectionId=" + connectionId;

        client.GetAsync(url);
    }

}