Ricardo de Souza Moura wrote:

> I have read about CMP and DAO, and Some people said that when I use
> CMP, DAO
> don't make sense...
> But
> What if I want to have the possibility to change to JDBC DAO for sample ?
> I would have to change all my business method, wouldn't I ?
> But If I make a DAO like this:
>
> public class EJBFamilyDAO implements IFamilyDAO {
>
>     Context context = null;
>     FamilyHome home = null;
>
>     /*
>      * (non-Javadoc)
>      *
>      * @see
> com.shoptime.integration.crmerp.persistence.IFamilyDAO#insertFamily(java.lang.String)
>
>      */
>     public void insertFamily(String pFamilyName) {
>           // TODO Auto-generated method stub
>           home.create(pFamilyName);
>     }
>
>     /*
>      * (non-Javadoc)
>      *
>      * @see
> com.shoptime.integration.crmerp.persistence.IFamilyDAO#findFamilyByName(java.lang.String)
>
>      */
>     public FamilyVO findFamilyByName(String pName) {
>           // TODO Auto-generated method stub
>           return home.findBFamilyByName(pName);
>     }
>
>     public EJBFamilyDAO() {
>           try {
>                context = new InitialContext();
>                home = context.lookup(...);
>           } catch (Exception e) {
>                e.printStackTrace();
>           }
>     }
>
> }
> Wouldn't it be more easy to change my business method? I only need
> change my
> DAO Implementation, don't I ?
>
> Thanks in advance
>
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I am working on a project and I have same problem, but now I have a
problem: "transactions".
I want to start my project using only JDBC and in future switch to
entity bean (this is a requirement).
The problem is that my DAO may manage transaction inside their methods
or a DAO may partecipate to an external transaction.

So I have for each DAO impl. two constructor:

  class MyDAOImpl extends DAO {
     MyDAO() {}
     MyDAO(Transaction t) {}
  }

  class MyDAOFActory {
     DAO create();
     DAO create(Transaction t);
  }

where Transaction is a wrapper class of Connection.

Suppose my DAO should partecipate to a transaction in a business method
like this:

business() {
  Transaction t = new Transaction();

  DAO dao = factory.create(t);
  DAO dao2 = factory.create(t);
  ...
  dao.method1()
  dao.method2();
  dao2.method3();
  ...
  t.commit();
}

the problem now is: when I switch to EJB CMP I do not need to manage
transaction, so Will I change all my business method?

I do not know how to solve this problem (the implementation of DAO
reported above has been extracted from Firestorm dao generator tool).

Any suggestion is welcome.

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