SDSU CS 696 Emerging Technologies: Distributed Objects
Spring Semester, 1998
Naming Service Example
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© 1998, All Rights Reserved, SDSU & Roger Whitney
San Diego State University -- This page last updated 21-Apr-98

Contents of Doc 27, Naming Service Example

  1. References
  2. Using OrbixWeb Naming Service
    1. Example - Server & NS Separate

References


CORBAservices, chapter 3, Naming Service Specification, March 1995

OrbixWeb Programmer's Guide, IONA Technologies PLC, November 1997, chapter 8 Making Objects Available in OrbixWeb pp. 180-202


Doc 27, Naming Service Example Slide # 2

Using OrbixWeb Naming Service


Method 1. Use the OrbixWeb Names Browser
Add objects to the name space structure via a GUI

Method 2. Write a program to add/remove objects
The following example uses a separate program to add objects from a server to the naming service
It is possible to have the server add object to the naming service
See /opt/OrbixWeb3.0/demos/namesStaff on rohan for an example


Doc 27, Naming Service Example Slide # 3
Finding the Default Naming Context

Method 1 CORBA Compliant and OrbixWeb Recommended

Use resolve_initial_references
   protected static NamingContext getRootContext() throws 
      org.omg.CORBA.ORBPackage.InvalidName
      {
      org.omg.CORBA.Object initNCRef = 
         ORB.init().resolve_initial_references("NameService");

      return NamingContextHelper.narrow(initNCRef);
      }


Method 2 Use Orbix bind()
   NamingContext  rootContext = 
      NamingContextHelper.bind( "root:NS", hostName );

Method 3 Use the root naming context's IOR 
Doc 27, Naming Service Example Slide # 4

Example - Server & NS Separate

Server 
import IE.Iona.OrbixWeb._CORBA;
import IE.Iona.OrbixWeb.CORBA.ORB;

public class GreeterServer
   {
   public static void main (String args[])
      {
      org.omg.CORBA.ORB orb =
         org.omg.CORBA.ORB.init();
      
      try
         {
         Greeter  upTown = 
            new _tie_Greeter( new TieGreeter( "Upton"), "up");

         Greeter  beach = 
            new _tie_Greeter( new TieGreeter( "Bob"), "low");

         Greeter mountain = new InheritedGreeter( "Mike", "high");

         Greeter  general = new InheritedGreeter( "Gloria");

         _CORBA.Orbix.impl_is_ready( "Visitor", 
                              _CORBA.IT_INFINITE_TIMEOUT);

         System.out.println("Server going Down");
         }
      catch ( org.omg.CORBA.SystemException corbaError)
         {
         System.out.println("Exception " + corbaError);
         }
      }
   }

Doc 27, Naming Service Example Slide # 5
Registering Program 
import IE.Iona.OrbixWeb._OrbixWeb;
import IE.Iona.OrbixWeb._CORBA ; 
import org.omg.CORBA.ORB;
import org.omg.CORBA.SystemException ; 
import org.omg.CORBA.CosNaming.* ; 
import org.omg.CORBA.CosNaming.NamingContextPackage.*;

public class RegisterInNS
   {
   public static void main(String args[]) throws Exception
      {
      org.omg.CORBA.ORB orb =
         org.omg.CORBA.ORB.init();
      
      NamingContext rootContext = getRootContext( orb );
      
      NameComponent[] ca = new NameComponent[1];
      ca[0] = new NameComponent("Califorina", "");

      NamingContext stateContext = 
         rootContext.bind_new_context( ca );
      
      NameComponent[] city = new NameComponent[1];
      city[0] = new NameComponent("Del Mar", "");
      stateContext.bind( city, getGreeter( "low") );
   
      city[0] = new NameComponent("Julian", "");
      stateContext.bind( city, getGreeter( "high") );
      
      city[0] = new NameComponent("San Diego", "");
      stateContext.bind( city, getGreeter( "up") );
      
      }


Doc 27, Naming Service Example Slide # 6
// Registering Program Continued 


   protected static Greeter getGreeter( String marker )
      {
      String hostname = "eli.sdsu.edu";
      String serverLabel = ":Visitor";
      return GreeterHelper.bind(marker +  serverLabel, 
                                 hostname);
   }
   
   protected static NamingContext getRootContext( 
         ORB myOrb) throws 
            org.omg.CORBA.ORBPackage.InvalidName
      {
      org.omg.CORBA.Object initNCRef = 
         myOrb.resolve_initial_references("NameService");
         
      return NamingContextHelper.narrow(initNCRef);
      }

   }

Doc 27, Naming Service Example Slide # 7
Client Code 
import IE.Iona.OrbixWeb._OrbixWeb;
import IE.Iona.OrbixWeb._CORBA ; 
import org.omg.CORBA.ORB;
import org.omg.CORBA.SystemException ; 
import org.omg.CORBA.CosNaming.* ; 
import org.omg.CORBA.CosNaming.NamingContextPackage.*;

public class SimpleNSClient {
   public static void main (String args[]) {
      org.omg.CORBA.ORB orb = org.omg.CORBA.ORB.init();
      
      Greeter californiaGreeter;
      NamingContext rootContext;

      try {
         rootContext = getRootContext();

         NameComponent[] ca = new NameComponent[2];
         ca[0] = new NameComponent("Califorina", "");
         ca[1] = new NameComponent("Julian", "");

         org.omg.CORBA.Object greeterRef = 
            rootContext.resolve( ca );

         californiaGreeter = GreeterHelper.narrow( greeterRef);

         System.out.println( californiaGreeter.name());
      }
      catch ( Exception corbaError) {
         System.out.println("Exception " + corbaError);
      }
   }
   
   protected static NamingContext getRootContext() throws 
      org.omg.CORBA.ORBPackage.InvalidName
      {
      org.omg.CORBA.Object initNCRef = 
         ORB.init().resolve_initial_references("NameService");

      return NamingContextHelper.narrow(initNCRef);
      }
   }


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