Re: ClassCastException after retrieving an Entry

Hi

Just a general note - if anyone is trying to use OSGi with Jini please do
take a look at the Newton Project at www.codecauldron.org - its open source
and it takes away all these classloader issues. Honestly its easy and it
just works.

You may also be interested in the following article on EclipseZone from
earlier this week: http://www.eclipsezone.com/eclipse/forums/t87966.html.

Blatant promotion over :-)

Regards
Mike

Mike Francis
www.paremus.com

-----Original Message-----
From: Dan Creswell [mailto:[email protected]]
Sent: 04 January 2007 18:45
To: [email protected]
Subject: Re: ClassCastException after retrieving an Entry

Christian Hager wrote:
> Hello,
>
>
> As for the PREFFERED.LIST file I don't really know. I didn't create on so
I
> asume there is none. I'm using the Standard Installation of Jini 2.1 and
> Blitz 1.29 on Win XP.
>
> I tried the thing with  the classloader and it gives me
>
> My Entry Loader:
>
sun.rmi.server.LoaderHandler$Loader@1930ebb["ahttp://computegrid:computegrid
@192.168.0.200/codebase/codebase.jar"]
>
> My TaskEntry Loader:
> org.eclipse.osgi.internal.baseadaptor.DefaultClassLoader@1079781
>

Uh oh, what's this OSGI classloader doing in here????

> for the following code
>
> Entry entry = javaSpace.take (taskTmpl, txn, 30000);
> System.out.println("My Entry Loader: "+
entry.getClass().getClassLoader());
> System.out.println("My TaskEntry Loader: "+
> TaskEntry.class.getClassLoader());
> TaskEntry task = (TaskEntry) javaSpace.take (taskTmpl, txn, 30000);
>
> the Exception then occurs in the 4th line of the code and is as follows
>
> java.lang.ClassCastException: org.ac.computegrid.TaskEntry
> at org.ac.computegrid.worker.GenericWorker.loop(GenericWorker.java:123)
> at org.ac.mvc.ExtThread.run(ExtThread.java:399)
> at java.lang.Thread.run(Unknown Source)
>
> The TaskEntry class is in the codebase and as seen above and seems to be
> taken from there.
>
> Since it seems to be a classloading problem it might also be important
that
> my worker is an eclipse rcp plugin.
>

And there's the answer - yes that's very important because eclipse has
it's way of doing classloading and Blitz and other Jini bits have
another way of structuring it all.

I think it's time to insert some usages of:

com.sun.jini.start.ClassLoaderUtil.displayClassLoaderTree()

For each of these classloaders...

e.g.

ClassLoaderUtil.displayClassLoaderTree(TaskEntry.class.getClassLoader());

> Thanks again for any help
>
> Christian Hager
>
>
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