public <T> Future<T> submit(Address target, Callable<T> task){
            if (task == null) throw new NullPointerException();
            if (target == null) throw new NullPointerException();
            List<Address> members = rpc.getTransport().getMembers();
            if(!members.contains(target)){
                throw new IllegalArgumentException("Unknown node "+target.toString());
            }
            Address me = rpc.getAddress();
            DistributedExecuteCommand<T> c = null;
            if(target.equals(me)){
                c = factory.buildDistributedExecuteCommand(clone(task), me, null);
            } else {
                c = factory.buildDistributedExecuteCommand(task, me, null);
            }
            DistributedRunnableFuture<T> f = new DistributedRunnableFuture<T>(c);
            executeFuture(target, f);
            return f;
        }