This week's book giveaway is in the OCPJP forum.
We're giving away four copies of OCA/OCP Java SE 7 Programmer I & II Study Guide and have Kathy Sierra & Bert Bates on-line!
See this thread for details.
The moose likes EJB Certification (SCBCD/OCPJBCD) and the fly likes CMR  doubts (Head first EJB) Big Moose Saloon
  Search | Java FAQ | Recent Topics | Flagged Topics | Hot Topics | Zero Replies
Register / Login


Win a copy of OCA/OCP Java SE 7 Programmer I & II Study Guide this week in the OCPJP forum!
JavaRanch » Java Forums » Certification » EJB Certification (SCBCD/OCPJBCD)
Bookmark "CMR  doubts (Head first EJB)" Watch "CMR  doubts (Head first EJB)" New topic
Author

CMR doubts (Head first EJB)

Devendra Inamdar
Greenhorn

Joined: Sep 23, 2005
Posts: 20
I have a doubt about CMR example (Page 396, Head First EJB, MovieBean code).
Movie bean has a CMR field directorID. In the relational database schema, directorID is a foreign key in the Movie table. ejbCreate method in Movie bean takes directorID as a parameter but it is not set using abstract CMP methods being a CMR field. If a record is inserted in Movie table by container after completion of ejbCreate, is directorID attribute for that record set to null? What if there is a NOT NULL constraint on directorID column of the Movie table?
The setDirector is called during ejbPostCreate to link the Movie Bean with the Director Bean at this point who is responsible for updating the foreing key(Movie.directorID) in the underlying database?
If a client gets a reference to an existing Movie bean by calling a finder method, how does container establish the link between Movie and Director bean since directorID is not being supplied from client in this case?

thanks
Devendra
Devendra Inamdar
Greenhorn

Joined: Sep 23, 2005
Posts: 20
Hi,
I am still waiting on this. Anyone?
regards,
Devendra
Hemavathy Viswanathan
Greenhorn

Joined: Dec 26, 2006
Posts: 17
Hi Devendra,


Hemavathy Viswanathan<br />SCJP 1.4/ SCWCD 1.4/ SCBCD 1.3
Hemavathy Viswanathan
Greenhorn

Joined: Dec 26, 2006
Posts: 17
hi Devendra,
To answer the 2nd part of your question: how does the container establish the link between the Movie bean and the director bean? This is the answer:

The whole point of having the CMR field (Director) in the Movie bean should answer your question. Container managed relationship fields are those that explain how the two beans are associated to each other.
 
I agree. Here's the link: http://aspose.com/file-tools
 
subject: CMR doubts (Head first EJB)