Hi Ivan,
I’ve double-checked the javadoc for javax.naming.spi.ObjectFactory, and I
believe that the JNDI Services Specification is correct in requiring that any
exceptions thrown by an ObjectFactory should be returned to the caller.
The javadoc for ObjectFactory, found at:
http://download.oracle.com/javase/6/docs/api/javax/naming/spi/ObjectFactory.html
mentions that an ObjectFactory’s getObjectInstance() method must return null if
the factory cannot resolve the object. An Exception thrown from an
ObjectFactory indicates that an error occurred while trying to create an object
based on the object information, and that no other factories are to be tried.
It is up to the ObjectFactory implementation to handle the fact that the first
argument in getObjectInstance() may or may not be of type
javax.naming.Reference.
Hope this helps…
Bob
From: Ivan Dubrov [mailto:[email protected]]
Sent: Thursday, September 16, 2010 12:41 AM
To: OSGi Developer Mail List
Subject: [osgi-dev] JNDI Services Specification, faulty (?) object factories
Hi,
I have a question about the correct behaviour of the JNDI Services
Specification implementation.
Sometimes JNDI provider calls getObjectInstance providing "resolved" object
(not a reference, javax.naming.Reference), for example instance of JMS
javax.jms.ConnectionFactory. According to the 126.4/6 [1], my implementation of
JNDIProviderAdmin tries to convert object with all possible factories. The
problem is that most JBoss factories expect object passed to be
javax.naming.Reference, so ClassCastException is thrown. According to the
specification (see the end of the 126.4 [2]), the exception must be propagated
to the caller, breaking the JNDI resolution rules.
The question is how to behave correctly in that case? Should I ignore exception
in my JNDI Services implementation? Should I consult factories only if object
is reference?
As a workaround, I have implemented property "<someprefix>.refOnly" that means
factory should be consulted only if object passed is a javax.naming.Reference,
which works, but I'm afraid I have missed something in the spec.
[1] Snippet from the OSGi Service Platform Release 4, Enterprise Specification
4.2, section 126.4/6:
>If the description was a Reference and without a factory class name specified,
>or if the description was not of type Reference, then attempt to convert the
>object with each Object Factory service (or Dir Object Factory service for
>directories) service in ranking order until a non-null value is returned.
[2] Exceptions handling:
>If an Exception occurs during the use of an Object Factory Builder service
>then this exception should be logged but must be ignored. If, however, an
>Exception occurs during the calling of a found ObjectFactory or
>DirObjecFactory object then this Exception must be re-thrown to the caller of
>the JNDI Provider Admin service.
--
WBR,
Ivan S. Dubrov
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