Value Objects still relevant in EJB 2.0?

Question

I came across the concept of using Value Objects to get better performance from EJBs as they reduce the number of remote calls to invoke to retrieve object property values.
However, with the introduction of LocalHome and Local interfaces for EJB 2.0, is it still useful to have value objects to pass data around, typically between EJBs and the Controller (typically servlets/JSPs or session beans that implement business logic)?

Answer 1

Not so fast.
I wouldn't be so quick to get rid of VOs simply because local interfaces exist now. Keep in mind that using local interfaces is not always the right answer to your problem (since there are still situations where the client and server are not co-located within a given VM).
Also, there are times when the brittleness of your API should be considered. If a method takes many parameters, it is often benificial to pass a single VO as a paramater rather than multiple individual parameters. This really comes into play when methods are modified to take different arguments (e.g. adding a new argument).
Consider a method on a bean used to update a student's records for example.public StudentVO update(String firstName, String middleInitial, String lastName, int age, String ssn, String status) throws UpdateException; is much more brittle than public StudentVO update(StudentVO student) throws UpdateException;Consider what would happen if a design change makes GPA and gradeLevel part of a student's profile.
The second method's signature would remain the same. The signature of the first method however would now read public StudentVO update(String firstName, String middleInitial, String lastName, int age, String ssn, String status, float gpa, int gradeLevel) throws UpdateException; This change would "break" the calls made by any callers of this method. While there are pros and cons to this (as well as other ways to solve this issue, such as method overloading, etc.), it is something to consider when deciding whether a value object should be used in certain situations.
Hope this adds another point of view to the discussion.
Note: I'm using Value Object (VO), Data Transfer Object (DTO) and Transfer Object (TO) to me the same thing here.