Hi Ulvi
Don't forget that RMI also hides the detail of networking from you. Because it appears that you are just calling a normal method on a normal class, it can be easier for that junior programmer to understand.
Using sockets will generally use fewer resources all round, not just bandwidth and numbers of messages sent, but also fewer processes on the server, and fewer maintenance threads running.
The disadvantages for RMI are not a big concern in this case - we are only shipping very small messages around, and we are not expecting to have thousands of users.
Have I totally failed to give you a clear idea of which one to use? Good
Regards, Andrew