PQ58039: CLASS <CLASSNAME> VIOLATES LOADER CONSTRAINTS: DEFINITION MISMATCH BETWEEN PARENT AND CHILD WHEN SERVLET PASSES PARMS TO AN EJB

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APAR status
Closed as program error.

Error description
When an application servlet is instantiated and passes a class
reference to a method call to an EJB, and the EJB is
instantiated, neither looks into the Web cache for the class
reference. This causes a problem because now there are 2
copies of the referenced class. The next reference to the class
from outside the scope of the current classloader could cause
the following error:
  Class <classname> violates loader constraints:  definition
  mismatch between parent and child loaders.  The
  visibility mode is Module (0).
Local fix Problem summary
****************************************************************
* USERS AFFECTED: All users of the WebSphere Application       *
*                 Server Version V4.0.1 for z/OS and OS/390.   *
****************************************************************
* PROBLEM DESCRIPTION: When an application servlet is          *
*                      instantiated and passes a class         *
*                      reference to a method call to an EJB,   *
*                      and the EJB is instantiated, neither    *
*                      looks into the Web cache for the class  *
*                      reference. This causes a problem        *
*                      because now there are 2 copies of the   *
*                      referenced class. The next reference to *
*                      the class from outside the scope of the *
*                      current classloader could cause the     *
*                      following error:                        *
*                        Class <classname> violates loader     *
*                        constraints:  definition mismatch     *
*                        between parent and child loaders.     *
*                        The visibility mode is Module (0).    *
****************************************************************
* RECOMMENDATION:                                              *
****************************************************************
When an application servlet is instantiated and passes a class
reference to a method call to an EJB, and the EJB
is instantiated, neither looks into the Web cache for the
class reference. This causes a problem because now there are 2
copies of the referenced class. The next reference to the class
from outside the scope of the current classloader could cause
the following error:
 Class <classname> violates loader constraints:
   definition mismatch between parent and child
   loaders.  The visibility mode is Module (0).

The Application Server code loads a class only when it is used,
rather than when it is referenced, causing the above problem.
Problem conclusion
The Application Server code previously loaded a class only when
it was used rather than when it was referenced, causing the
problem in Version V4.0.1.  We now force all the EJB classes
to be loaded when they are referenced. The EJB classes, EJBStub
classes, and the EJB method/constructor parameter/return
classes are also cached when they are first loaded. A lookup is
done in the cache for a class prior to loading the class in
order to avoid loader constraints.

This change affects COMPID 5655A9800 R401 for z/OS and OS/390.
The code changes are stored in CMVC under defect PQ58039.

401Y
EJSJWCWC

* Cross Reference between External and Internal Names
Temporary fix Comments
APAR information
APAR number PQ58039
Reported component name WEBSPHERE OS/39
Reported component ID 5655A9800
Reported release 401
Status CLOSED PER
PE NoPE
HIPER NoHIPER
Submitted date 2002-02-19
Closed date 2002-02-28
Last modified date 2002-04-01

APAR is sysrouted FROM one or more of the following:

APAR is sysrouted TO one or more of the following:

Modules/Macros
EJSJWCWC          

Fix information
Fixed component name WEBSPHERE OS/39
Fixed component ID 5655A9800

Applicable component levels
R401 PSY UQ63580    UP02/03/12 P F203

  Fix is available
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Document Information


Product categories: Software > Application Servers > Distributed Application & Web Servers > WebSphere Application Server for z/OS
Operating system(s):
Software version: 401
Software edition:
Reference #: PQ58039
IBM Group: Software Group
Modified date: Apr 1, 2002