Re: smart/dynamic proxies and java 1.5

> Anyone out there using RMI Smart Proxies/Dynamic Proxies (Rickard
> Oberg posted the way to do this here a long time ago) with Java 1.5?
> (or is there a new better way to use Dynamic Proxies in 1.5)

See below.

> We're inserting proxies on both the client and server side to do
> stuff, logging, security etc.
>
> We're been using them successfully with Java 1.3 and 1.4 but they no
> longer work with 1.5.  I figured I check to see if anyone else has
> already run into this problem.
>
> We're getting StubNotFoundExceptions.
>
> Exception with exportObject on PortableRmiObject
> (//xxx.xxx.xxx.165:64101/)RmiFileManagerImpl[RMAUnicastServerRef2
> [liveRef:
> [endpoint:[xxx.xxx.xxx.165:52010,rma.rmi.server.SinglePortServerSocketFactory@84eda628,rma.rmi.server.LimitedPortServerSocketFactory@52a393bc](local),objID:[0]]]]
> Error:java.rmi.StubNotFoundException: Stub class not found: $Proxy0_Stub; nested exception is:
> java.lang.ClassNotFoundException: $Proxy0_Stub
> java.rmi.StubNotFoundException: Stub class not found: $Proxy0_Stub; nested exception is:
> java.lang.ClassNotFoundException: $Proxy0_Stub
>         at sun.rmi.server.Util.createStub(Util.java:274)
>         at sun.rmi.server.Util.createProxy(Util.java:122)
>         at sun.rmi.server.UnicastServerRef.exportObject(UnicastServerRef.java:179)
>         at sun.rmi.server.UnicastServerRef.exportObject(UnicastServerRef.java:161)
>         at hec.server.PortableRmiObject.exportObject(PortableRmiObject.java:812)
>         at hec.server.PortableRmiObject.exportObject(PortableRmiObject.java:720)
>         at hec.server.PortableRmiObject.exportServer(PortableRmiObject.java:365)
>         at hec.server.PortableRmiObject.rebindServer(PortableRmiObject.java:228)
>         at hec.server.RMIServer.startServer(RMIServer.java:156)
>         at hec.server.RMIProxyServer.<init>(RMIProxyServer.java:66)
>         at hec.server.FileManager.<init>(FileManager.java:23)
>         at hec.server.FileManager.main(FileManager.java:92)
>         Caused by: java.lang.ClassNotFoundException: $Proxy0_Stub
>                 at java.lang.Class.forName0(Native Method)
>                 at java.lang.Class.forName(Class.java:242)
>                 at sun.rmi.server.Util.createStub(Util.java:268)
>
> ClassNotFoundException usually means its not in the classpath.  But
> with the Smart Proxy stuff its never been in the classpath.  It gets
> loaded through the use of a custom class loader.  My guess is that
> how RMI does classloading was changed 1.5, but that's only a guess.

From the name of the stub class being sought, it appears that you are
trying to export an instance of a dynamic proxy class as a remote
object.  I would need to see more details about the particular trick
that you are using to get that to work with JDK versions earlier than
5.0 in order to speculate about why it no longer works with 5.0.  The
procedure used by the JDK RMI implementation to load the stub class
for a remote object should be effectively the same in 5.0 as it was in
previous versions, although the surrounding code was changed a bit.
But the above stack trace seems to indicate direct use of sun.rmi.*
APIs, which would mean that compatibility shouldn't be expected
anyway:

        http://java.sun.com/products/jdk/faq/faq-sun-packages.html

With JDK 5.0, exporting remote objects that are instances of dynamic
proxy classes is more directly supported because rmic-generated stub
classes are usually no longer required:

        http://java.sun.com/j2se/1.5.0/docs/guide/rmi/relnotes.html

But that feature doesn't work in the case of the above stack trace
because of the particular sun.rmi.server.UnicastServerRef method being
used to export the object.  The issue is pretty similar to that of the
public UnicastRemoteObject.exportObject(Remote) method described here:

        http://archives.java.sun.com/cgi-bin/wa?A2=ind0501&L=rmi-users&P=556

-- Peter

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