ASP.NET MVC服务器可以通过IIS向其客户端推送通知，以下是一个解决方法的代码示例：

1. 创建一个ASP.NET MVC项目，并在Global.asax.cs文件中添加以下代码：

using System.Web.Mvc;
using System.Web.Routing;

namespace YourProjectNamespace
{
    public class MvcApplication : System.Web.HttpApplication
    {
        protected void Application_Start()
        {
            AreaRegistration.RegisterAllAreas();
            RouteConfig.RegisterRoutes(RouteTable.Routes);

            // 启用WebSocket
            System.Web.HttpContext.Current.SetWebSocketEnabled();
        }
    }
}

2. 创建一个控制器，例如NotificationController.cs，并添加以下代码：

using System;
using System.Collections.Concurrent;
using System.Net;
using System.Net.Http;
using System.Net.WebSockets;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Web.Http;

namespace YourProjectNamespace.Controllers
{
    public class NotificationController : ApiController
    {
        // 用于存储 WebSocket 连接的集合
        private static ConcurrentDictionary _clients = new ConcurrentDictionary();

        [HttpGet]
        public HttpResponseMessage Connect(string clientId)
        {
            if (HttpContext.Current.IsWebSocketRequest)
            {
                HttpContext.Current.AcceptWebSocketRequest(ProcessWebSocket);
                return Request.CreateResponse(HttpStatusCode.SwitchingProtocols);
            }
            else
            {
                return Request.CreateResponse(HttpStatusCode.BadRequest);
            }
        }

        private async Task ProcessWebSocket(WebSocketContext context)
        {
            var webSocket = context.WebSocket;
            string clientId = context.QueryString["clientId"];

            _clients.TryAdd(clientId, webSocket);

            byte[] buffer = new byte[1024];
            while (webSocket.State == WebSocketState.Open)
            {
                WebSocketReceiveResult result = await webSocket.ReceiveAsync(new ArraySegment(buffer), CancellationToken.None);

                if (result.CloseStatus.HasValue)
                {
                    _clients.TryRemove(clientId, out WebSocket removedWebSocket);
                    await webSocket.CloseAsync(result.CloseStatus.Value, result.CloseStatusDescription, CancellationToken.None);
                }
            }
        }

        [HttpPost]
        public async Task Notify(string clientId, string message)
        {
            if (_clients.TryGetValue(clientId, out WebSocket webSocket))
            {
                var buffer = new ArraySegment(Encoding.UTF8.GetBytes(message));
                await webSocket.SendAsync(buffer, WebSocketMessageType.Text, true, CancellationToken.None);
                return Request.CreateResponse(HttpStatusCode.OK);
            }
            else
            {
                return Request.CreateResponse(HttpStatusCode.NotFound);
            }
        }
    }
}

3. 在Web.config文件中添加以下代码，以便启用WebSocket：

4. 现在，您可以通过发送GET请求到/api/notification/connect?clientId={clientId}来建立WebSocket连接。在客户端建立连接后，您可以通过发送POST请求到/api/notification/notify?clientId={clientId}&message={message}来向客户端推送通知。

请注意，以上代码示例仅提供了一个基本的实现，实际应用中可能需要进行更多的错误处理和验证。