Steve L
9/26/2004 12:07:00 AM
Subject: .NET Remoting problem - exception "Object Reference not set to
instance of an object"
From: aacool <a@b.c>
Newsgroups: microsoft.public.dotnet.framework
Hi,
I need some help with a .NET Remoting problem - an "Object Reference not
set to instance of an object"exception is thrown in the client when
accessing methods of a remote object.
Basically, I have a server implemented as a Windows Service, using a
config file, and implementing an object from the General namespace. The
server code is below.
////Data definitions namespace
namespace General
{
/// <summary>
/// Interface to access data object
/// </summary>
public interface ICustomerManager
{
Customer getCustomer(int id);
int getAge(int id);
}
/// <summary>
/// Data object implementation
/// </summary>
[Serializable]
public class Customer
{
//put all functions in an interface
protected int cust_id;
public string firstName,lastName;
public DateTime BirthDate;
public Customer(int id)
{
cust_id = id;
}
}
}
/////////Server code
namespace WindowsServiceSrvr
{
public class ServiceSrvr : System.ServiceProcess.ServiceBase
{
private ComponentModel.Container components = null;
public static string SVC_NAME = "ServiceSrvr";
public static string cfgFile = "server.config";
public ServiceSrvr(){...}
static void Main()
{
System.ServiceProcess.ServiceBase[] ServicesToRun;
ServicesToRun = new ServiceProcess.ServiceBase[] {
new ServiceSrvr() };
evt.Source = SVC_NAME;
ServiceProcess.ServiceBase.Run(ServicesToRun);
}
protected override void OnStart(string[] args)
{
RemotingConfiguration.Configure(cfgFile);
}
}
[Serializable]
public class CustomerMgr : MarshalByRefObject,
General.ICustomerManager
{
public CustomerMgr()
{
}
public Customer getCustomer(int custId)
{
General.Customer cust = new Customer(custId);
cust.BirthDate = new DateTime(1945,12,12);
return cust;
}
public int getAge(int custId)
{
General.Customer cust = this.getCustomer(custId);
TimeSpan tmp = DateTime.Today.Subtract(cust.BirthDate);
return (int)tmp.Days/355;
}
}
}
My client uses a Generated_General.dll generated by soapsuds
soapsuds -url:http://localhost:custSrvr?wsdl -oa:gen.dll
The client code is:
namespace ClientUsingService
{
/// <summary>
/// Implementation of client - config file, soapsuds generated
/// metaschema, and a server running as a windows service
/// </summary>
class Client
{
public static string cfgFile = "app.config";
[STAThread]
static void Main(string[] args)
{
try
{
RemotingConfiguration.Configure(cfgFile);
// Instantion CustomerMgr interface
WindowsServiceSrvr.CustomerMgr custMgr = new
WindowsServiceSrvr.CustomerMgr();
if(custMgr!=null)
Console.WriteLine("Got server connection");
General.Customer cust = custMgr.getCustomer(5434);
Console.WriteLine(
cust.BirthDate.ToShortDateString());
// throws Invalid Reference Exception
Console.WriteLine("Customer 5434 is {0} yrs
old",custMgr.getAge(5443));
Console.ReadLine();
}
catch(Exception ex)
{
Console.WriteLine(ex.Message);
Console.WriteLine(ex.StackTrace);
Console.ReadLine();
}
}
}
}
The problem is that when the methods of custMgr are called by the client
the exception
"Object Reference not set to an instance of an object" is thrown.
I am at my wits end!! Please help explain what is wrong.