code: public TransactionImpl getCurrentTransaction()
      {
          TransactionImpl tx = tx_table.get(Thread.currentThread());
          if(tx == null)
          {
              throw new TransactionNotInProgressException("Calling method needed transaction, but no transaction found for current thread :-(");
          }
          return tx;
      }
docs: Returns the current transaction for the calling thread.
  
  @throws org.odmg.TransactionNotInProgressException
  {@link org.odmg.TransactionNotInProgressException} if no transaction was found.