Hello All I have read the posting by herve attia i just read the explanation given by Herve Attia for using the cmp and bmp with dao at top of this posting. It is mentioned that it is not good to have all the tables to be represented as CMP. And for example of customer ,address,credit card it is said that customer can be made as entity bean with address and credit card as bmp with dao. My doubts 1 We have CMR in ejb2.0 so should we use relations instead of using bmp with dao for adress and creditcard. If we do so we are anyway representing each table with a cmp. 2 When we design CMP beans do we have the flexibility to have different columns from different tables to be represented as one CMP in ejb1.1 or ejb2 . If this facility is there is it useful to implement. 3 The scea part 2 is based on ejb1.1 or ejb2 4 I have read that CMP is better than scalable than BMP why is it so is it just because container manages persistent for CMP. 5 Have anyone found difficulties with cmp in real projects and felt that bmp is better. I feel that CMP may be difficult to maintain if we do use CMR also then it will be more difficult to maintain. With BMP we do have full control and is better though we have to take care of persistent.