Design pattern question

[singh santosh]

hi ,
I have encountered a question ..

Q >What are the using the Transfer Object pattern?(select two)

1)The type of the actual data source can be specified at deployement time.
2)The data clients are independent of the data source vendor API.
3)It increases the performance of data accessing routines.
4)It allows the clients to access the data source through EJBs.
5)It allows resource locking in an efficient way.

My answer :b,c but they have mentioned as a,b

So whats according to u are correct answers??

regards
-santosh

[Yi Yuan]

This question is from Manning SCWCD Study Guide. I have encountered it too. I think there is something wrong with the question. The correct should be "the benefits of DAO" rather than "of TO".

[Sunder Ganapathy]

Transfer Object encapsulates data in a simple bean-like way.
It returns many items of data at once, instead of makig repeated
calls ( to get attributes one at a time ).
Due to both the above reasons, options C & D are out.
Many items of data being returned, lack of performance is a factor.
Of course network performance is increased due to less calls.