Send GCM message from Server (Downstream HTTP JSON)

Question

Could you provide a simple code (or a link) to send a simple message from my C# server to Android devices via Downstream HTTP JSON?

I use next simple c# code to send messages using Downstream HTTP Plain Text. But I need to do it with JSON because I need to use the Priority field.

private string SendMessageUsingGCM(String sRegistrationId, string sTextToSend, string sCollapseKey)
{
    String GCM_URL = @"https://gcm-http.googleapis.com/gcm/send";
    bool flag = false;
    string sError = "";

    StringBuilder sb = new StringBuilder();
    sb.AppendFormat("registration_id={0}&collapse_key={1}", sRegistrationId, sCollapseKey);
    sb.AppendFormat("&delay_while_idle=0&priority=high"); //priority field will not work on this kind of messages
    sb.AppendFormat("&data.msg=" + HttpUtility.UrlEncode(sTextToSend));  //To send special characters like ä, ë, arabs...
    string msg = sb.ToString();

    HttpWebRequest req = (HttpWebRequest)WebRequest.Create(GCM_URL);
    req.Method = "POST";
    req.ContentLength = msg.Length;
    req.ContentType = "application/x-www-form-urlencoded";
    req.Timeout = 20000;

    req.Headers.Add("Authorization:key=" + MyAthorizationKey);

    try
    {
        using (StreamWriter oWriter = new StreamWriter(req.GetRequestStream()))
        {
            oWriter.Write(msg);
        }

        using (HttpWebResponse resp = (HttpWebResponse)req.GetResponse())
        {
            using (StreamReader sr = new StreamReader(resp.GetResponseStream()))
            {
                string respData = sr.ReadToEnd();

                if (resp.StatusCode == HttpStatusCode.OK)   // OK = 200
                {
                    if (respData.StartsWith("id="))
                        flag = true;
                    else
                        sError = respData;
                }
                else if (resp.StatusCode == HttpStatusCode.InternalServerError)   // 500
                    sError = "Internal server error. Try later.";
                else if (resp.StatusCode == HttpStatusCode.ServiceUnavailable)    // 503
                    sError = "Server not available temnporatily. Try later.";
                else if (resp.StatusCode == HttpStatusCode.Unauthorized)          // 401
                    sError = "The API Key is not valid.";
                else
                    sError = "Error: " + resp.StatusCode;
            }
        }
    }
    catch (WebException e)
    {   //The remote server returned an error: (502) Bad Gateway. //Más info: http://stackoverflow.com/questions/2159361/error-502-bad-gateway-when-sending-a-request-with-httpwebrequest-over-ssl
        //The remote server returned an error: (500) Internal Server Error. Más info: http://stackoverflow.com/questions/4098945/500-internal-server-error-at-getresponse
        sError = "WebException: " + e.ToString();
    }
    catch (Exception e)
    {
        sError = "Exception: " + e.ToString();
    }


    if (flag == true)
        return "Ok";

    return "Error " + sError;
}

score 0 · Accepted Answer · answered Mar 15 '16 at 18:52

private string SendMessageUsingGCM(String sRegistrationId, string sTextToSend, string sCollapseKey)
{
    String GCM_URL = @"https://gcm-http.googleapis.com/gcm/send";
    bool flag = false;
    string sError = "";

    string msg = "{";
    msg += "\"to\": \"" + sRegistrationId+ "\","; 
    msg += "\"collapse_key\": \"" + sCollapseKey + "\", ";
    msg += "\"priority\": \"high\",";
    msg += "\"data\": {\"msg\": \"" + sTextToSend+ "\" }";
    msg += "}";

    HttpWebRequest req = (HttpWebRequest)WebRequest.Create(GCM_URL);
    req.Method = "POST";
    req.ContentLength = msg.Length;
    req.ContentType = "application/json";
    req.Timeout = 2000;
    req.Headers.Add("Authorization:key=" + MyAthorizationKey);

    try
    {
        Byte[] byteArray = Encoding.UTF8.GetBytes(msg);
        req.ContentLength = byteArray.Length; //<--To send special characters like ä, ë, arabs... http://stackoverflow.com/questions/32537219/error-httpwebrequest-bytes-to-be-written-to-the-stream-exceed-the-content-len
        Stream writer = req.GetRequestStream();
        writer.Write(byteArray, 0, byteArray.Length);

        using (HttpWebResponse resp = (HttpWebResponse)req.GetResponse())
        {
            using (StreamReader sr = new StreamReader(resp.GetResponseStream()))
            {
                string respData = sr.ReadToEnd();

                if (resp.StatusCode == HttpStatusCode.OK)   // OK = 200
                {
                    if (respData.StartsWith("id="))
                        flag = true;
                    else
                        sError = respData;
                }
                else if (resp.StatusCode == HttpStatusCode.InternalServerError)   // 500
                    sError = "Internal server error. Try later.";
                else if (resp.StatusCode == HttpStatusCode.ServiceUnavailable)    // 503
                    sError = "Server not available temnporatily. Try later.";
                else if (resp.StatusCode == HttpStatusCode.Unauthorized)          // 401
                    sError = "The API Key is not valid.";
                else
                    sError = "Error: " + resp.StatusCode;
            }
        }
    }
    catch (WebException e)
    {   //The remote server returned an error: (502) Bad Gateway. //Más info: http://stackoverflow.com/questions/2159361/error-502-bad-gateway-when-sending-a-request-with-httpwebrequest-over-ssl
        //The remote server returned an error: (500) Internal Server Error. Más info: http://stackoverflow.com/questions/4098945/500-internal-server-error-at-getresponse
        sError = "WebException: " + e.ToString();
    }
    catch (Exception e)
    {
        sError = "Exception: " + e.ToString();
    }


    if (flag == true)
        return "Ok";

    return "Error " + sError;
}

Send GCM message from Server (Downstream HTTP JSON)

1 Answers1