At 09:34 AM 2/22/99 -0600, you wrote:
>Personally I think this issue about passing partial object graphs is
>irrelevant in some ways. Two issues come to mind:
>
>First not all CORBA implementations of EJB support Java serializable types,
>most allow standard CORBA structs but not PBV as we are used to in Java RMI.
>In these cases you have to develop your PBV objects to be very simple with
>public attributes so that it can double as CORBA structs if necessary.
>
>Second, PBV should be done with care. I have outlined some ground rules for
>PBV in a paper I submitted to the EJB workshop
>(http://www.inprise.com/events/ejbdesign/submissions/Pass-by-Value.html).
>Generally, PBV is a bad idea in Component Transaction Monitor (CTM)
>applications because of problems with object equivalence and performance.
>You can use PBV as described in my paper, but anything more complicated will
>cause problems in the long run.
>
>You can't design EJB solutions like business object systems because you are
>dealing with solutions that span address spaces. Your approach needs to be
>completely different stressing the use of session beans to manage workflow
>and act as an interface to your clients (applets, servlets, etc.), and
>limited use of entity beans on the client. Entity bean should focus on
>consistent and safe access to related data.
Question Richard,
On the immutable object part where get methods are the only methods
provided. As a client:
1) How would I create a new address object?
2) If through a Entity bean, what about data validation across a network.
If my business object has eight attributes, that is eight set calls to the
bean and possibly more if one set fails on data validation. Granted, you
could marshall the sets as one call, but that makes things icky. If your
PBV business object also has set methods and has the ability to do data
validation, you eliminate that network traffic and just hand off the
validated Address object to the Entity bean for insertion. The only
validation you would have on the Entity bean side would be referential
integrity checks where it would be near the database.
Perry Hoekstra - [EMAIL PROTECTED]
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