public static string SendNotification(string message)
        {
            string SERVER_API_KEY = "AAudxqUSs:APA9....QVzG8IE-uCV2NBBk";
            var SENDER_ID = "694564231175";
            var value = message;
            WebRequest tRequest;
            tRequest = WebRequest.Create("https://fcm.googleapis.com/fcm/send");
            string MyProxyHostString = "someproxy.com";
            int MyProxyPort = 8080;
            IWebProxy proxy = new WebProxy(MyProxyHostString, MyProxyPort);
            string proxyUsername = @"login";
            string proxyPassword = @"password";
            proxy.Credentials = new NetworkCredential(proxyUsername, proxyPassword);
            tRequest.Proxy = proxy;

            tRequest.Method = "post";
            tRequest.ContentType = "application/json";

            tRequest.Headers.Add(string.Format("Authorization: key={0}", SERVER_API_KEY));
            tRequest.Headers.Add(string.Format("Sender: id={0}", SENDER_ID));
            var postData = new
            {
                to = "/topics/all",
                notification = new
                {
                    body = "tests",
                    title = "God bless",
                    sound = "Enabled"

                }
            };
            var serializer = new JavaScriptSerializer();
            var json = serializer.Serialize(postData);
            Console.WriteLine(postData);
            Byte[] byteArray = Encoding.UTF8.GetBytes(json);
            tRequest.ContentLength = byteArray.Length;

            Stream dataStream = tRequest.GetRequestStream();
            dataStream.Write(byteArray, 0, byteArray.Length);
            dataStream.Close();

            WebResponse tResponse = tRequest.GetResponse();

            dataStream = tResponse.GetResponseStream();

            StreamReader tReader = new StreamReader(dataStream);

            String sResponseFromServer = tReader.ReadToEnd();


            tReader.Close();
            dataStream.Close();
            tResponse.Close();
            return sResponseFromServer;
        }