/*
* NOTE: This copyright does *not* cover user programs that use HQ
* program services by normal system calls through the application
* program interfaces provided as part of the Hyperic Plug-in Development
* Kit or the Hyperic Client Development Kit - this is merely considered
* normal use of the program, and does *not* fall under the heading of
* "derived work".
*
* Copyright (C) [2004-2008], Hyperic, Inc.
* This file is part of HQ.
*
* HQ is free software; you can redistribute it and/or modify
* it under the terms version 2 of the GNU General Public License as
* published by the Free Software Foundation. This program is distributed
* in the hope that it will be useful, but WITHOUT ANY WARRANTY; without
* even the implied warranty of MERCHANTABILITY or FITNESS FOR A
* PARTICULAR PURPOSE. See the GNU General Public License for more
* details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
* USA.
*/
package org.hyperic.hq.transport.util;
import java.io.Externalizable;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
/**
* The handler for making asynchronous invocations. If the invocations must
* be guaranteed, then any state associated with the invocation must be
* made {@link Externalizable}.
*/
public abstract class AsynchronousInvocationHandler
implements Runnable, Externalizable {
private static final Log _log = LogFactory.getLog(AsynchronousInvocationHandler.class);
private boolean _guaranteed;
/**
* Public no-arg constructor required for externalization.
*/
public AsynchronousInvocationHandler() {}
/**
* Creates an instance.
*
* @param guaranteed <code>true</code> if the invocation is guaranteed.
*/
public AsynchronousInvocationHandler(boolean guaranteed) {
_guaranteed = guaranteed;
}
/**
* Delegates to {@link #handleInvocation()} but swallows any exceptions
* throw during invocation handling.
*/
public final void run() {
try {
handleInvocation();
} catch (Exception e) {
_log.error("Error while handling invocation", e);
}
}
/**
* @return <code>true</code> if the invocation is guaranteed.
*/
public final boolean isInvocationGuaranteed() {
return _guaranteed;
}
/**
* Subclasses should only extend this method, never override it.
*
* @see java.io.Externalizable#readExternal(java.io.ObjectInput)
*/
public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException {
_guaranteed = in.readBoolean();
}
/**
* Subclasses should only extend this method, never override it.
*
* @see java.io.Externalizable#writeExternal(java.io.ObjectOutput)
*/
public void writeExternal(ObjectOutput out) throws IOException {
out.writeBoolean(_guaranteed);
}
/**
* Handle the invocation.
*
* @throws Exception if invocation handling fails.
*/
public abstract void handleInvocation() throws Exception;
}