Fun with compound primary keys

[Michael Jara]

It took me a while to figure this out, so I thought I'd post it.   If you are using a compound primary key class in your CMP entity bean, and you forget to make it implement java.io.Serializable, Orion may do some really strange things.   In my case, I have an entity bean which represents a many to many mapping of other entity beans, called "TypeDescriptionPair".  This entity bean's create method took two other entity beans as parameters, "EventType" and "EventDescription".  The create method would simply extract the primary key from each of these and store it.  So, I was doing something like this to test the implementation:   ... eventTypes[0] = eventTypeHome.create(0, "eventType0"); eventTypes[1] = eventTypeHome.create(1, "eventType1"); ... eventDescription[0] = eventTypeHome.create(0, "eventDescription0"); eventDescription[1] = eventTypeHome.create(1, "eventDescription1"); ... typeDescriptionPairHome.create(eventTypes[0], eventDescription[0]); typeDescriptionPairHome.create(eventTypes[1], eventDescription[1]);   The very last statement would throw a CreateException, because all EventType and EventDescription remote objects had mysteriously been nullified!  After hours of debugging, I realized that "TypeDescriptionPair"s primary key class did not implement java.io.Serializable.  As soon as I added "implements java.io.Serailzable" to the primary key class, everything was magically fixed.   Mike