Issue 1696:  Proposed change to orb.init (java-rtf)
Source:  (, )
Nature:  Uncategorized Issue
Severity: 
Summary: Summary: How should ORB.init() be fixed?
 
 ORB.init() should try to find an ORB class in the following order:
 
   1. Try loading the class using Class.forName(String className) --  this is
      to take into account the possibility that the ORB implementation class
      is in the core (for example: com.sun.CORBA.iiop.ORB). If that fails,
   2. Try loading the class using Class.forName(String className, boolean
      initialize, ClassLoader cl), where cl ==
      ClassLoader.getSystemClassLoader(). In the case of an applet, cl ==
      applet.getClass().getClassLoader().
 
 For sophisticated users who might have a well-behaved ClassLoader that knows
 how to load the ORB implementation, it might be necessary to have a new
 ORB.init() that takes a ClassLoader as an argument. For example:
 
      ORB.init(String[] args, Properties props, ClassLoader cl);
 
 In this case, ORB.init() would load the class using the class loader that
 was passed by the user instead of the system class loader.
 

Resolution: closed issue
Revised Text: 
Actions taken:
July 20, 1998: received issue
February 23, 1999: closed issue
Discussion: 

End of Annotations:=====
Return-Path: <nash@sp3at21.hursley.ibm.com>
Date: Fri, 17 Jul 1998 22:57:27 +0100
From: Simon Nash <nash@hursley.ibm.com>
Reply-To: nash@hursley.ibm.com
Organization: IBM
To: java-rtf@omg.org
Cc: issues@omg.org
Subject: Proposed change to orb.init

We discussed this briefly on Thursday's call.  As promised, I am
attaching a written proposal from Sun explaining why this is needed
and how it would work.

   Simon 
-- 
Simon C Nash, IBM Java Technology Centre, Hursley, UK
MailPoint 146, x245156  Tel. 01962 815156 or +44-1962-815156
Internet: nash@hursley.ibm.com  Notes mail: Simon Nash@ibmgb
            ORB.init()  -- Behaviour Change

Background

JDK1.2 has made a distinction in class loading by having the following
types
of class loaders:

   * Bootstrap class loader
   * System class loader (also called as the application class loader)

Bootstrap Class Loader

All classes in rt.jar are loaded by the bootstrap class loader. Stated
differently, the bootstrap class loader will only load the classes
from
rt.jar. -Xbootclasspath  can be used to replace rt.jar but the use of
-Xbootclasspath is discouraged.

System Class Loader

The system class loader looks at the system property java.class.path
(which
is either the value specified using -classpath or the CLASSPATH
environment
variable)  for classes after trying to load the class using the
bootstrap
class loader.

Class.forName

There are two Class.forName's in JDK1.2:

   * Class.forName(String className)
   * Class.forName(String className, boolean initialize, ClassLoader
cl)

How does this relate to ORB.init()?

All classes in the package org.omg.CORBA are in rt.jar. The ORB API
--
org.omg.CORBA.ORB.init() -- uses Class.forName(String className)to
load the
ORB implementation class. Class.forName(String className) loads
classes
using its caller's class loader, which in this case is the bootstrap
class
loader. Because the bootstrap class loader will only load classes from
rt.jar, it becomes impossible to load ORB implementation classes which
are
not in rt.jar (unless -Xbootclasspath is used on every invocation of
java to
work around this problem).

How should ORB.init() be fixed?

ORB.init() should try to find an ORB class in the following order:

  1. Try loading the class using Class.forName(String className) --
this is
     to take into account the possibility that the ORB implementation
class
     is in the core (for example: com.sun.CORBA.iiop.ORB). If that
fails,
  2. Try loading the class using Class.forName(String className,
boolean
     initialize, ClassLoader cl), where cl ==
     ClassLoader.getSystemClassLoader(). In the case of an applet, cl
==
     applet.getClass().getClassLoader().

For sophisticated users who might have a well-behaved ClassLoader that
knows
how to load the ORB implementation, it might be necessary to have a
new
ORB.init() that takes a ClassLoader as an argument. For example:

     ORB.init(String[] args, Properties props, ClassLoader cl);

In this case, ORB.init() would load the class using the class loader
that
was passed by the user instead of the system class loader.