使用长轮询替代：

js：

        //===============SendEvent================
        //控制是否继续轮询
        var isEventClose = 1;
        //创建XMLHttpRequest
        function createXmlHttpRequest() {
            if (window.ActiveXObject) { //如果是IE浏览器    
                return new ActiveXObject("Microsoft.XMLHTTP");
            } else if (window.XMLHttpRequest) { //非IE浏览器    
                return new XMLHttpRequest();
            }
        }    
        //初始化
        var xhr = createXmlHttpRequest();
        //方法入口
        function EdgeEvent() {
            xhr.open("post", "/eventEdge.webapi",true);
            xhr.onreadystatechange = AppendMessage;
            xhr.send();
        }
        //增加消息
        function AppendMessage() {
            if (xhr.readyState == 4 && xhr.status == 200) {
                if (xhr.responseText != null && xhr.responseText.length > 0) {
                    $("#publishMessage").append(xhr.responseText);
                }
                if (isEventClose == 0) {
                    setTimeout(EdgeEvent, 500);
                }
            } 
        };
        //===============SendEvent================

后台：

        public static void SendEdgeEvent(HttpListenerResponse response)
        {
            var output = response.OutputStream;
            response.Headers.Add("Cache-Control", "no-cache");
            response.ContentType = "text/xml;charset=UTF-8";
            while (_messageQuery.Count > 0)
            {
                var message = _messageQuery.Dequeue();
                var data = Encoding.UTF8.GetBytes($"{ message }\n");
                output.Write(data, 0, data.Length);
                output.Flush();
            }
        }