EJB unidirectional CMR

[Vladas Razas]

Hi,
How should I implement unidirectional relationship? Let's say I have this kind of relationship (btw from page 432):
Foo (0-1) -> Bar (0-1)
Do I have to have CMR fields in both Foo and Bar? If so then what does "unidirectional relationship" means in terms of implementation? Or maybe the only difference is I do not put Foo accessor methods into Bar class remote(or local) interface(s). In that case... does it makes any difference is it unidirectional or bidirectional to container?
My best regards

[Philippe Maquet]

Hi Vladas,
The <cmr-field> element is optional. To describe a unidirectional relationship, you simply define a <cmr-field> in *only one* of both <ejb-relationship-role> elements.
Best,
Phil.

[Mikalai Zaikin]

Hi, Vladas,
Let's look at relationship Customer-HomeAddress.
Customer must know his/her address, but Address does not need to know anything about it's customer.
Here is the piece of DD for this relationship:

  
<ejb-relation>
<ejb-relation-name>Customer-HomeAddress</ejb-relation-name>
<ejb-relationship-role>
<ejb-relationship-role-name>
Customer-has-a-Address
</ejb-relationship-role-name>
<multiplicity>One</multiplicity>
<relationship-role-source>
<ejb-name>CustomerEJB</ejb-name>
</relationship-role-source>
<cmr-field>
<cmr-field-name>homeAddress</cmr-field-name>
</cmr-field>
</ejb-relationship-role>
<ejb-relationship-role>
<ejb-relationship-role-name>
Address-belongs-to-Customer
</ejb-relationship-role-name>
<multiplicity>One</multiplicity>
<cascade-delete/>
<relationship-role-source>
<ejb-name>AddressEJB</ejb-name>
</relationship-role-source>
</ejb-relationship-role>
</ejb-relation>

It was taken from SCBCD Study Guide web-site.
As you can see, Address definition does not have cmr-field element. This means, Address have no idea about customer (the relation is unidirectional)
This and much-much more you can find there
Cheers!!!

[Vladas Razas]

Thanks !
And likewise if I don't have CMR field it means I do NOT put abstract setter/getter for it
Nice site Mikalai! Now I see that bean with only remote interface may only have unidirectional relationship from one side.
My best regards

[Mikalai Zaikin]

Now I see that bean with only remote interface may only have unidirectional relationship from one side.

yeah, you are absolutely right, bean with only Remote interface
can have [unidirectional] relationship to other bean (with local interface), but nobody can access it in CMR.