Shiv,
You raise a good point on Addresses if they are shared in your design.
But for phone numbers you might design a flexible model for handling many
different numbers (e.g. business, home, mobile, fax, cottage...). Why hard
code the slots in the parent object when you could have a collection of
phone numbers instead? IMHO, phone numbers are a great example for dependent
objects...
Regards,
-Chris.
> -----Original Message-----
> From: Shiv Kumar [SMTP:[EMAIL PROTECTED]]
> Sent: Tuesday, July 11, 2000 10:41 AM
> To: [EMAIL PROTECTED]
> Subject: Entity bean questions
>
> Hi all
>
> 1. What is a good example of 'dependant object'? The spec gives an
> example of employee record. It says an employee record should be
> modelled as entity beans, but employee address and phone number
> should not be.
>
> * What if all employee addresses are maintained in a different
> table in the db?
>
> * And phone number of course will be a field in my EB. Why should I
> ever model it as a dependant object?
>
> I think, dependant objects are only useful when used with SBs. With
> EB, I am not sure where it will be useful. Because, with CMP bean,
> all fields that will be stored in db should be declared public. I can
> not, for example, have :
>
> public MyClass myObject;
>
> where, MyClass is a dependant object
>
> class MyClass { public int x; public int y }
>
> and in my deployment descriptor,
>
> <cmp-field>
> <field-name>myObject.x</field-name>
> </cmp-field>
> <cmp-field>
> <field-name>myObject.y</field-name>
> </cmp-field>
>
> At least WebLogic 5.1 did not provide this feature.
>
> In one case, my entity bean represented a table which had 20 columns.
> Instead of taking all 20 params in ejbCreate() method, I had a helper
> class which encapsulated these columns :
>
> class Columns implements java.io.Serializable {
> }
>
> // MyHome.java
> public MyRemote create(Columns cols) throws ...
>
> Because of the stupid restriction that all persistable data members
> should be declared in the bean class, I end up duplicated all data
> members of 'class Columns' in my bean's class, like :
>
> // MyBean.java
> public Columns cols;
>
> public MyPK ejbCreate(Columns cols) throws ... {
> this.m = cols.m;
> this.n = cols.n;
> this.o = cols.o;
> this.p = cols.p;
> this.x = cols.x;
> this.y = cols.y;
> this.z = cols.z;
> }
>
> instead of simply doing,
>
> public MyPK ejbCreate(Columns cols) throws ... {
> if (cols != null) this.cols = cols
> }
>
>
> 2. I was never successfully able to model a EB which refers to another
> EB like,
>
> // CompanyBean.java
> class CompanyBean {
> public int id; // PK
> public int name;
> }
>
> // UserBean.java
> class UserBean {
> public int id; // PK
> public String name;
> public Company company;
> }
>
> I had to always use 'public int companyID' and rely on the
> constraints provided by the underlying db.
>
> BTW, I was always using WebLogic 5.1. I would like to know how other
> containers solve this problem.
>
> TIA.
> --
> shiv
> [EMAIL PROTECTED]
>
>
>
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