Phantom Context lookup or Is "java:" some kind of keyword ? ? ?

Question

I'm attempting to implement my own Context for capturing performance information out of a third party applications. I've run into a strange problem where the method call doesn't aways work even though the signature appears to be correct, with the only diffence being is the contents of the String that is passed in as a parameter. If the string starts with "java:" the method is not called. In the example below only "lookup [my-ruleHome]" is printed, I'd have expected "lookup [java:comp/UserTransaction]" to be printed as well.
package com.blah;
import javax.naming.*;
import java.util.Hashtable;
public class MyContext implements Context {
    Context realProviderCtx = null; 
    public MyContext (Hashtable env) throws NamingException {
      env.put(Context.INITIAL_CONTEXT_FACTORY, "weblogic.jndi.WLInitialContextFactory");
      realProviderCtx = new InitialContext(env);
    public Object lookup(String name) throws NamingException {
       System.out.println("lookup [" + name + "]");
       return realProviderCtx.lookup(name);
package com.blah;
import java.io.*;
// Packages for Servlets
import javax.servlet.*;
import javax.servlet.http.*;
import java.util.Collection;
import java.util.Iterator;
import java.util.Properties;
import java.util.Vector;
import javax.naming.Context;
import javax.naming.InitialContext;
import javax.ejb.FinderException;
import javax.naming.NamingException;
import java.rmi.RemoteException;
import javax.rmi.PortableRemoteObject;
import javax.transaction.UserTransaction;
import javax.ejb.CreateException;
import javax.ejb.RemoveException;
public class SomeServlet extends HttpServlet {
  public void init(ServletConfig config) throws ServletException {
    super.init(config);
  * Method to process HTTP GET requests.
  public void doGet(HttpServletRequest p_req, HttpServletResponse p_res)
                                        throws ServletException, IOException {
     Collection rules = getRules();
     //  Do something here to display a webpage
  public Collection getRules() {
    Collection rules = null;
    Properties env = new Properties();
    env.put(Context.INITIAL_CONTEXT_FACTORY, "blah.MyInitialContextFactory");
    env.put(Context.PROVIDER_URL, "t3://app-dev-01.blah.com:7003");                                                                           
    try
      Context cntx = new InitialContext(env);
      UserTransaction ut = (UserTransaction) cntx.lookup( "java:comp/UserTransaction" );
      ut.begin();
      RuleHome ruleHome = (RuleHome) cntx.lookup("my-ruleHome");
      rules = ruleHome.findAll();
      ut.commit();
    catch (NamingException ne)
       System.out.println("NamingException " + ne.toString());
       ne.printStackTrace();
    catch (FinderException fe)
       System.out.println("FinderException " + fe.toString());
    catch (java.rmi.RemoteException re) {
       System.out.println("RemoteException " + re.toString());
    } catch (javax.transaction.NotSupportedException nse) {
       System.out.println("NotSupportedException " + nse.toString());
    } catch (javax.transaction.RollbackException re) {
       System.out.println("RollbackException " + re.toString());
    } catch (javax.transaction.SystemException se) {
       System.out.println("SystemException " + se.toString());
    } catch (javax.transaction.HeuristicMixedException hme) {
       System.out.println("HeuristicMixedException " + hme.toString());
    } catch (javax.transaction.HeuristicRollbackException hre) {
       System.out.println("HeuristicRollbackException " + hre.toString());
    return rules;
}

Answer 1

I think I figured out my own issue. InitialContext is actually wrappering my context. Based on the documentation in http://java.sun.com/j2se/1.4.1/docs/api/javax/naming/InitialContext.html anything before the ":" is the scheme InitialContext's lookup method will use a different context provider based on the scheme and that's why my method was not being executed. Apparently the context provider for the scheme "java" was receiving the method call.