*/
public void writeExternal(ObjectOutput out) throws IOException {
if( data !=null ) {
Iterator iterator = data.keySet().iterator();
while(iterator.hasNext()) {
InvocationKey key = (InvocationKey) iterator.next();
if( key.isTransient() )
continue; // don't serialize this item.
Object value = data.get(key);
out.writeObject(key);
out.writeObject(value);
}