The normal rules regarding transactions apply to Java methods. The start and duration of database transactions is critical to the synchronization process. Transactions must be started and ended only by the MobiLink server. Explicitly committing or rolling back transactions on the synchronization connection within a Java method violates the integrity of the synchronization process and can cause errors.
These rules apply only to the database connections created by the MobiLink server and, in particular, to SQL statements returned by methods. If your classes create other database connections, you are free to manage them as you please.