Exceptions - Java User Exceptions

Description: 
	The Java server throws a Java user exception within a remotely called method which is
	caught by the .Net client.
	
	According to the standard (i.e. OMG's IDL-to-Java mapping) a CORBA user exception defined 
	as OMG IDL is mapped to a Java exception derived from org.omg.CORBA.UserException. Java 
	RMI user exceptions (derived from java.rmi.RemoteException), however, are mapped to an IDL 
	valuetype (according to the OMG Java-to-IDL mapping). To use the standard CORBA exception
	propagation mechanism these valuetypes have to be wrapped into a (generated) standard IDL 
	exception with a derived name ending with 'Ex', e.g.: 
	
		MyUserException  --> exception MyUserEx        (containing a MyUserException)
		MyUserProblem    --> exception MyUserProblemEx (containing a MyUserProblem)
		MyUserEx         --> exception MyUserExEx      (containing a MyUserEx)
		
	MiddCor extents this mechanism to all Java user exceptions. Being a regular valuetype, though, 
	the user exception requires an implentation on the client side.
	
	The mechanism for propagating user exceptions from Java to .Net is essentially transferring 
	an object by value (see also the Objects by value example.)

Source: 
	MinCor\DemoJava\Exceptions

Mapping: 
	java.lang.Exception  <--->  Middsol.CORBA.UserException

Example 

The Java server:

    Interface     : Exceptions\Greetings.java
    Implementation: Exceptions\GreetingsImpl.java
    Exception     : Exceptions\MyUserException.java

    
    public class MyUserException extends java.lang.Exception {
	
        public int iId;

        public MyUserException( int i) 
        {
            super(); 
            iId = i;
        }
		
        public MyUserException() 
        {
            super(); 
            iId = 0;
        }
    }
    

The .Net client:

    Implementation: ClientImpl.cs
    IDL-Files     : Exceptions.idl
                    Exceptions_Ex.idl
    Generated     : Exceptions.cs
	
	
    Exception Implementation: MyUserExceptionImpl.cs

    
    public class MyUserExceptionImpl: Exceptions.MyUserException
    {
        public MyUserExceptionImpl()
        {
        }
	
        public MyUserExceptionImpl( int a_iValue)
        {
            this.iId = a_iValue;
        }
    }       
          
 	
    Retrieve the exception (ClientImpl.cs):
    
    try
    {
        string strRet = oGreetings.hello( "Middsol");
    }
    catch( Exceptions.MyUserEx ex)
    {
        Exceptions.MyUserException oMyUserException = (Exceptions.MyUserException)ex.value;
        a_oFrmClt.writeLog( "Exception catched: ");
        a_oFrmClt.writeLog( "  Exceptions.MyUserExceptionID ");
        a_oFrmClt.writeLog( "  Id:"+  oMyUserException.iId);
        a_oFrmClt.writeLog( "");

        a_oFrmClt.writeLog( "Stacktrace:");
        a_oFrmClt.writeLog( oMyUserException.ToString());
    }
	

    
    Note, that we have to add several items to the list of assemblies to be searched for 
    by the .Net Reflection. This list is set using the "-AddAssembly" parameter during ORB 
    initialization:
    
    private static string[] m_strORBInit = {"-ORBEndpoint iiop://localhost:8545/portspan=100", 
                                            "-ORBInitRef NameService=corbaloc:iiop:1.2@localhost:1050/NameService",
                                            "-ORBDebug",
                                            "-AddAssembly DotNetClient.exe,JavaBuiltinTypesCF.dll,MinCorCF.dll" };