Jiango,
Your customer EJB is a good of an aggregate Entity.
- Contact is a too small cheunk of data to be implemented as an
entity EJB.
- Customer and Contact is an aggregate.
A contact is linked to only 1 customer
A contact do not exist outside of the scope of a customer
You can retreive and modify the contacts through the customer interface:
public interface Customer implements EJBObject
public Collection getContacts(); // Collection of contacts
public UUID addContact(ContactInfo contact);
public void remContact(UUID contactPK);
public void changeContactType(UUID pk, String type);
public void changeContactInfo(UUID pk, Info type);
and so on
}
ContactInfo is a serializable class, but not an EJB.
The choice between CMP and BMP is dependent of your application server
persistence
engine. If the AS can manage persistence for aggregate, use a CMP, else you
need to write the code in a BMP and keep the save the ContactInfo list in
the ejbStore method.
Hope this help
Tibo.
>-----Original Message-----
>From: Jianguo Wang [mailto:[EMAIL PROTECTED]]
>Sent: Thursday, February 01, 2001 11:42 AM
>To: [EMAIL PROTECTED]
>Subject: bean design problem for one to many relationship
>
>
>Dear friends,
>
>I have a design problem about one to many relationship. Can
>anyone there give me
>some suggestions,
>
>For simplicity's sake, let's say I have two tables Person(UID,
>FirstName, LastName)
>with primary key (UID) and ContactInfo(UID, Type, Detail) with
>primary key (UID, Type).
>A person may have more than one ContactInfo. For example,
>
>A record in the table "Person" is (777, John, Smith)
>Corresponding to this person, there are two records in the
>table "ContacInfo" like
>(777, Email, [EMAIL PROTECTED])
>(777, Phone, (850)123-4567)
>
>These information are provided at a time and can be saved in
>array (mainly ContactInfo).
>When I try to insert them into database, can I implement it as
>CMP? or I have to
>implement it as BMP? If I can do with CMP, does it mean that I
>have to make a loop
>to invoke home.create(UID, Type, Detail)?
>
>Thank you very much.
>
>-John
>
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