java serialisation | change domain object implementation on server side

Question

We have got a very hard bug. The equals- Method in our domain object DomainOrder was implemented wrong. The problem is, that the domain object is used by our clients incl. all old versions. So the clients must be updated too.

Clients communicate with server over RMI (JEE-6)

We have to fix it as soon as possible, but there are too many clients. So our idea was to fix the issue temporarily on the server side. But I'm not sure it would work.

current situation, our result Set contains just one object, cause equals returns true for different object:

[...]
List<DBOrder> list = orderService.getOrders(criteria);
Set<DomainOrder> orders = new HashSet<>();
for(DBOrder dborder : list){
    orders.add(convertDBOrderToDomain(dborder)); // mapping new DomainOrder(..)
}
[...]

How would I fix it on server side:

List<DBOrder> list = orderService.getOrders(criteria);
Set<DomainOrder> orders = new HashSet<>();
for(DBOrder dborder : list){
    final DomainOrder domainOrder = convertDBOrderToDomain(dborder);

    // temp fix for all old versions.
    orders.add(new DomainOrder(){

        private DomainOrder delegate = domainOrder ; 

        @Override
        public Long getId(){
           return delegate.getId();
        }
        [...]

        @Override
        public boolean equals(){
            return [fix];
        }

    }); 
}

So what do you think will it work? The iImportant goals are:

1. The client will get all Orders
2. The client will get NO error on deserialization of result.

I hope some own with experience in java serialisation and RMI can help me.

Answer 1

The important goals are:

1. The client will get all Orders

That's simply a matter of how you reimplement equals().

2. The client will get NO error on deserialization of result.

That requires that you don't change the serialVersionUID of the class concerned. If it doesn't have one, get it from the serialver tool before you change it.