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J2SE 1.4 breathes new life into the CORBA community, Part 4

Portable interceptors and the Interoperable Naming Service

By Tarak Modi, JavaWorld.com, 11/29/02

Page 4 of 5

.
.
.
public class BankClient
{
  public static void main(String args[])
  {
    try
    {
      // Create and initialize the ORB
      ORB orb = ORB.init(args, null);
      // Get the root naming context using corbaloc
      //org.omg.CORBA.Object objRef = orb.resolve_initial_references("NameService");
      org.omg.CORBA.Object objRef =
       orb.string_to_object("corbaloc:iiop:localhost:1050/NameService");
      // Use NamingContextExt instead of NamingContext. This is
      // part of the Interoperable naming Service.
      NamingContextExt ncRef = NamingContextExtHelper.narrow(objRef);
      // Resolve the object reference in Naming
      String name = "BankServer";
      System.out.println(args.length);
      if(args.length == 5)
        name = args[4];
        
      // Use corbaname instead of resolve_str
      // Bank theBank = BankHelper.narrow(ncRef.resolve_str(name));
      Bank theBank = BankHelper.narrow(orb.string_to_object("corbaname::localhost:1050#" + name));
      System.out.println("Obtained a handle on server object: " + theBank);
      AccountInformation accInfo = new AccountInformation();
      accInfo.accNum="";
      accInfo.accType = AccountType.NIL;
      Account[] accounts = theBank.findAccounts(accInfo);
      for(int i=0; i<accounts.length; i++)
        System.out.println("Account Number " + ((Account)accounts[i]).accountNumber());
      accounts[0].deposit((float)1.1);
    }
    catch(bank.UnknownException e)
    {
      System.out.print(e.reason);
    }
    .
    .
    .
}

Standardized bootstrapping

Most CORBA vendors include limited proprietary support for bootstrapping their ORB instances with services other than the ones they provide and sometimes even the ability to replace those services with other implementations. The INS standardizes both these abilities by defining standard ORB options for bootstrapping. To bootstrap a CORBA system, you must give it an object reference, which can be a stringified IOR or a corbaloc: URL. You can configure the ORB to return a customized CORBA service's handle from resolve_initial_references using either the ORBInitRef and/or ORBDefaultInitRef properties.

For example:

-ORBInitRef TraderService=corbaloc::XYZ.com:1050/TraderService
-ORBDefaultInitRef corbaloc:iiop:1.2:ABC.com:1050

The resolution order of when the ORB uses these options is as follows:

1. Objects registered with register_initial_references
2. -ORBInitRef
3. -ORBDefaultInitRef

Here's an example of replacing the standard J2SE 1.4 naming service implementation with another one running on XYZ.com on port 4076:

-ORBInitRef NameService=corbaloc::XYZ.com:4076/NameService

The naming service browser

The one tool that J2SE 1.4 does not offer is a naming service viewer to show what's in the naming service. So, as a going away present, I am providing you with such a tool: a naming service browser, shown in the figure below.

You can download the browser code from Resources. Assuming that your naming service (ORBD/tnameserv) is running on localhost at port 1050, you use this command line:

java cosnaming.utils.NamingBrowser -ORBInitialPort 1050 -ORBInitialHost localhost   

That's all folks

I've covered much ground in this four-part series on enterprise CORBA. I hope you feel confident enough to use J2SE's CORBA features in your own applications. The Java platform complements CORBA by providing Write Once, Run Anywhere portability, a highly productive implementation environment, and a robust platform. With J2SE 1.4's support for CORBA 2.3.1 and its associated enterprise features such as the POA, Portable Interceptors, and the INS, the reasons to use CORBA are even more compelling.