PI83439: ClassCastException thrown when using remote EJBs in servlet with parent-last classloading

Fixes are available

APAR status

Closed as program error.

Error description

In Liberty application server, with "parentLast"
classloading,
a ClassCastException is thrown when looking up a remote EJB
from the servlet within the same application.

This can happen when the application has an EJB module and a
web
module that both contain a remote interface (or whose
classloade
both have the remote interface in their class paths).

When generating stub class for the remote interface, the web
module's classloader should attempt the generation before
delegating to it's parent classloader (the application
loader).
it doesn't, and the application classloader ends up
generating
and loading the stub class using the remote interface that
it
loaded - that would then conflict with the remote interface
load
by the web module loader, resulting in a ClassCastException.

This exception could look like this:

javax.naming.NamingException: CWNEN1001E: The object
referenced
by the java:comp/env/ejb/MyEJB JNDI name could not be
instantiated.
If the reference name maps to a JNDI name in the deployment
descriptor bindings for the application performing the JNDI
lookup, make sure that the JNDI name mapping in the
deployment
descriptor binding is correct. If the JNDI name mapping is
correct, make sure the target resource can be resolved with
the
specified name relative to the default initial context.
[Root
exception is
com.ibm.wsspi.injectionengine.InjectionException:
CWNEN0030E: The server was unable to obtain an object
instance
for the java:comp/env/ejb/MyEJB reference.? The exception
message was: Cannot cast class
com.ibm.ws.sample.ejb._MyEJBHome_Stub to interface
com.ibm.ws.sample.ejb.MyEJB]

Local fix

1 - remove EJB module from WAR module ClassPath
2 - generate EJB Stubs with createEJBStubs command
and include in the EJB module (then ClassGenerator
would not be used)

Problem summary

****************************************************************
* USERS AFFECTED:  All users of IBM WebSphere Application      *
*                  Server Liberty - Runtime and Classloading   *
****************************************************************
* PROBLEM DESCRIPTION: ClassCastException thrown when using    *
*                      remote EJBs in servlet with parent-last *
*                      classloading                            *
****************************************************************
* RECOMMENDATION:                                              *
****************************************************************
In Liberty application server, with "parentLast" classloading, a
ClassCastException is thrown when looking up a remote EJB from
the servlet within the same application.

This can happen when the application has an EJB module and a web
module that both contain a remote interface (or whose
classloader both have the remote interface in their class
paths).

When generating stub class for the remote interface, the web
module's classloader should attempt the generation before
delegating to it's parent classloader (the application loader).
It doesn't, and the application classloader ends up generating
and loading the stub class using the remote interface that it
loaded - that would then conflict with the remote interface load
by the web module loader, resulting in a ClassCastException.

This exception could look like this:

javax.naming.NamingException: CWNEN1001E: The object referenced
by the java:comp/env/ejb/MyEJB JNDI name could not be
instantiated.
If the reference name maps to a JNDI name in the deployment
descriptor bindings for the application performing the JNDI
lookup, make sure that the JNDI name mapping in the deployment
descriptor binding is correct. If the JNDI name mapping is
correct, make sure the target resource can be resolved with the
specified name relative to the default initial context. [Root
exception is com.ibm.wsspi.injectionengine.InjectionException:
CWNEN0030E: The server was unable to obtain an object instance
for the java:comp/env/ejb/MyEJB reference.? The exception
message was: Cannot cast class
com.ibm.ws.sample.ejb._MyEJBHome_Stub to interface
com.ibm.ws.sample.ejb.MyEJB]

Problem conclusion

The fix for this APAR is to ensure that stubs are generated in
the current classloader before delegating to the parent when the
parentLast delegation policy is in effect.

The fix for this APAR is currently targeted for inclusion in fix
pack 17.0.0.3.  Please refer to the Recommended Updates page for
delivery information:
http://www.ibm.com/support/docview.wss?rs=180&uid=swg27004980

Temporary fix

Comments

APAR Information

APAR number
PI83439
Reported component name
WAS LIBERTY COR
Reported component ID
5725L2900
Reported release
855
Status
CLOSED PER
PE
NoPE
HIPER
NoHIPER
Special Attention
NoSpecatt / Xsystem
Submitted date
2017-06-21
Closed date
2017-08-14
Last modified date
2017-08-14

APAR is sysrouted FROM one or more of the following:
APAR is sysrouted TO one or more of the following:

Fix information

Fixed component name
WAS LIBERTY COR
Fixed component ID
5725L2900

Applicable component levels

R855 PSY
UP

[{"Business Unit":{"code":"BU059","label":"IBM Software w\/o TPS"},"Product":{"code":"SSD28V","label":"WebSphere Application Server Liberty Core"},"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"855","Line of Business":{"code":"LOB45","label":"Automation"}}]

Document Information

Modified date:
03 May 2022

Tips

PI83439: ClassCastException thrown when using remote EJBs in servlet with parent-last classloading

Fixes are available

Subscribe

APAR status

Closed as program error.

Error description

Local fix

Problem summary

Problem conclusion

Temporary fix

Comments

APAR Information

APAR number

Reported component name

Reported component ID

Reported release

Status

PE

HIPER

Special Attention

Submitted date

Closed date

Last modified date

APAR is sysrouted FROM one or more of the following:

APAR is sysrouted TO one or more of the following:

Fix information

Fixed component name

Fixed component ID

Applicable component levels

R855 PSY

Document Information

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