Handling Dao exceptions in service layer

Question

If my Dao layer throws Dao specific exceptions, then does handling them in my service layer consitute a leakage of concerns? If yes, then should I make the exceptions generi

Answer 1

Your DAO layer already leaks into the service layer when you do operations like:

userDAO.persist(user);

Exceptions, being a part of the API just like operation should be considered in the same way.

try {
    userDAO.persist(user);
} catch (DAOException e) {
    // looks fine to me
}

Leakage can happen with runtime exceptions, or when you rethrow exceptions

try {
    userDAO.persist(user);
} catch (SQLException e) {
    // sql implementation exposed
}

But even this sounds better than "layer independent" exceptions