[Quickfix-users] Quickfix 1.3 - Classloader problems with RMI-based JMX call

[<mat...@hs...>]

Hi,

We currently have a problem with the latest release of QuickfixJ 1.3 and
wonder if you could throw some light on this please.

We have a set of adapters which connect to various FIX-based ECNs, and
these are deployed together in a single web application.  Each adapter is
wrapped via Spring's MBeanExporter to be manageable, supporting start() and
stop() operations.  On the startup of the webapp, each adapter's start()
method is invoked:  all adapters start successfully.  However, if we stop
then restart an adapter through the JMX interface we have, an exception
results:
                              :
        Caused by: quickfix.ConfigError: error during session
initialization
                at
quickfix.mina.initiator.AbstractSocketInitiator.createSessions(AbstractSocketInitiator.java:138)
                at
quickfix.mina.initiator.AbstractSocketInitiator.<init>(AbstractSocketInitiator.java:77)
                at
quickfix.mina.initiator.AbstractSocketInitiator.<init>(AbstractSocketInitiator.java:67)
                at quickfix.SocketInitiator.<init>(SocketInitiator.java:47)
                at
com.somebank.imt.trading.fix.FixClientApplication.getConnector(FixClientApplication.java:117)
                at
com.somebank.imt.trading.fix.FixApplication.start(FixApplication.java:175)
                ... 38 more
        Caused by: java.lang.IllegalArgumentException: interface
quickfix.SessionStateListener is not visible from class loader
                at java.lang.reflect.Proxy.getProxyClass(Proxy.java:353)
                at java.lang.reflect.Proxy.newProxyInstance(Proxy.java:581)
                at quickfix.ListenerSupport.<init>(ListenerSupport.java:35)
                at quickfix.Session.<init>(Session.java:249)
                at
quickfix.DefaultSessionFactory.create(DefaultSessionFactory.java:159)
                at
quickfix.mina.SessionConnector.createSession(SessionConnector.java:112)
                at
quickfix.mina.initiator.AbstractSocketInitiator.createSessions(AbstractSocketInitiator.java:132)
                ... 43 more

I looked at the 1.3 source, in quickfix.ListenerSupport the following code
is executed.  (You are creating a dynamic proxy to override the toString
implementation)

    @SuppressWarnings("unchecked")
    public ListenerSupport(Class<?> listenerClass) {
        ClassLoader classLoader =
Thread.currentThread().getContextClassLoader();
        multicaster = Proxy.newProxyInstance(classLoader, new Class<?>[] {
listenerClass },
                new ListenerInvocationHandler());
    }

This is called from the quickfix.Session class when it is constructed:

    private final ListenerSupport stateListeners = new
ListenerSupport(SessionStateListener.class);

The first time this is invoked, we are in the context of a webapp
classloader, so SessionStateListener is loaded into this classloader within
Tomcat's classloader hierarchy.

The second time this is invoked, we are in the context of an RMI JMX call.
As such the context classloader off the thread is the classloader which has
loaded the MBeanServer implementation, which is part of rt.jar.  By this
time SessionStateListener has been loaded into the webapp classloader
though which is not visible to the other classloader higher in the
hierarchy so our restart fails.

Could you let us know how to fix this please?  We do not want to lift all
quickfix-based stuff higher in the hierarchy since we want our application
to remain deployable as a single webapp-based unit.

One other point, I notice that there is only one implementation of
SessionStateListener (namely SessionAdmin):  is there a good reason to load
this from the context of the calling thread.  Can you not do
this.getClass().getClassLoader() instead?  You cannot do this from within
the constructor, but maybe you could have a postInit() type method where
you would be able to do this.  Without this, other people will face the
same issue we do.

Any help is greatly appreciated and if I have missed something out or am
incorrect in my assumptions then many apologies!  Thanks very much for your
help on this and sorry for the long mail.


Thanks,
Matt

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