NullReferenceException was unhandled

Question

Hi could somebody please help me with this as i have been trying to fix it for hours!!!
I keep receving the "NullReferenceException was unhandled " message in the line in bold

public static Conditions GetCurrentConditions(string location)
{
Conditions c;
c = null;
c = new Conditions();

c.GetCurrentConditions();

XmlDocument xmlConditions = new XmlDocument();
xmlConditions.Load(string.Format("http://www.google.com/ig/api?weather={0}", location));
if (xmlConditions.SelectSingleNode("xml_api_reply/weather/problem_cause") != null)
{
c = null;
}
else
{
Conditions cond = new Conditions();
cond.Town = xmlConditions.SelectSingleNode("/xml_api_reply/weather/forecast_information/city").Attributes["data"].InnerText;
cond.Condition = xmlConditions.SelectSingleNode("/xml_api_reply/weather/current_conditions/condition").Attributes["data"].InnerText;
cond.TempC = xmlConditions.SelectSingleNode("/xml_api_reply/weather/current_conditions/temp_c").Attributes["data"].InnerText;
cond.TempF = xmlConditions.SelectSingleNode("/xml_api_reply/weather/current_conditions/temp_f").Attributes["data"].InnerText;
cond.Humidity = xmlConditions.SelectSingleNode("/xml_api_reply/weather/current_conditions/humidity").Attributes["data"].InnerText;
cond.Wind = xmlConditions.SelectSingleNode("/xml_api_reply/weather/current_conditions/wind_condition").Attributes["data"].InnerText;

}

return c;
}

Answer 1

Hi Bikesh Srivastava, I didn't exactly understand what you want to convey. I am doing my service method implementation in base class only.

public class Monitor : IMonitor

{

   public Task AddMonitor(Monitor mo)

   {

   // Implementation goes here 

   }

   public Task RemoveMonitor(Monitor mo)

   {

       // Implementation goes here

   }

}

 

But anyway my code id now working. Once i decorated my IMonitorCallback with (IsOneWay = true)] its started working perfectly.

interface IMonitorCallback

{

   [OperationContract(IsOneWay = true)]

   void OnAdded(Monitor data);

 

   [OperationContract(IsOneWay = true)]

   void OnRemoved(Monitor data);

}

 

Answer 2

I think you need to understand of WCF in deep.

because if you are creating interface  and implement then you have to declare all method in base class.

Answer 3

http://stackoverflow.com/questions/22466523/405-method-not-allowed-wcf-web-service-after-second-request