将json数据发送到远程服务器进行身份验证

Question

我想将身份验证详细信息发布到远程服务器，发送用户名，数据库名称和密码。我的服务器在Ubuntu上运行。但我得到错误无效的JSON数据：'' “POST / HTTP / 1.1”400 - 我是新手，在这个平台上工作，帮助我做错了。以下是我的代码：

private void SendDataButton_Click(object sender, RoutedEventArgs e)
{
    string url = "http://200.84.100.211:9875";
    string call = url + "/web/session/authenticate";
    HttpWebRequest request = (HttpWebRequest)WebRequest.Create(call) as HttpWebRequest;
    request.ContentType = "application/json";
    request.Method = "POST";
    request.BeginGetResponse(new AsyncCallback(SendData), request);
}

void SendData(IAsyncResult callbackResult)
{
    HttpWebRequest myRequest = (HttpWebRequest)callbackResult.AsyncState;
    Stream postStream = myRequest.EndGetRequestStream(callbackResult);
    string postData = "{'db':'demo_shruti','login':'admin','password':'admin'}";
    byte[] byteArray = Encoding.UTF8.GetBytes(postData);
    postStream.Write(byteArray, 0, byteArray.Length);
    postStream.Close();
    myRequest.BeginGetResponse(new AsyncCallback(FinishWebRequest), myRequest); 
}

void FinishWebRequest(IAsyncResult callbackResult)
{
    HttpWebRequest request = (HttpWebRequest)callbackResult.AsyncState;
    HttpWebResponse response = (HttpWebResponse)request.EndGetResponse(callbackResult);
    string responseString = "";
    Stream streamResponse = response.GetResponseStream();
    StreamReader reader = new StreamReader(streamResponse);
    responseString = reader.ReadToEnd();
    streamResponse.Close();
    reader.Close();
    response.Close();
    string result = responseString; 
}