1. can ant be used to produce a submission.jar? Is there any name required for submission.jar? (I know - it is to contain runme.jar) 2. how do you think? should read be between lock and unlock? i.e. every time we search for rows we have to read them to check if they match query. I think every row should be processed in locked code so the currently processed row will not be changed by update or delete 3. Data class testing: I created some JUnit tests which just run a lot of reading/writting threads. Do you think for automatic testing that is sufficient for threading?