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.