> -----Original Message-----
> From: James Cook [SMTP:[EMAIL PROTECTED]]
> Sent: Wednesday, February 25, 1998 1:31 PM
> To: [EMAIL PROTECTED]
> Subject: Inter-Object Business Rules & EJB Transactions
>
> Imagine an organizational chart for your company comprised of many People
> EJBs. Some People have descendants that represent their subordinates, and
> these people have subordinates, etc. I have multiple clients that can make
> changes to these objects.
>
> Suppose I have a business rule whereby, if a People EJB gets a bonus, the
> same
> bonus is applied to all of his/her subordinates. (Wish this was real
> life!)
>
> Stage set, here are the questions:
>
> 1) Would this business rule be enforced within a session EJB or the People
> (entity) EJB?
>
i'd do this with a direct jdbc call. no point in touching all the
affected entity beans directly to accomplish this (what if there are 10,000
subordinates - a single jdbc call will definitely be better). your choice
where you attach the method for doing it - ejbean or not.
> I will assume a session for the next questions...
>
> I can imagine a recursive routine that applies the bonus to the People EJB
> in
> question, gets a list of children, and calls itself for each child. This
> will
> effectively traverse the branches.
>
see above, don't waste time touching all the entity beans. do it
directly to the pstore and let the beans sync themselves. note that your
container must support this and you must have this support turned on (ie
Tengah dbIsShared must be set to true or this won't work).
> 2) Do the EJB transactions provide me with protection to prevent someone
> else
> from modifying the first People EJB while I'm off changing children.
>
if you start a tx and make a mod that record in your pstore will be
locked (implementation of the lock varies by vendor and even product version
within vendor).
> 3) Likewise, must I acquire some kind of lock on my entire set of People
> objects prior to making my changes. What if someone deletes a People EJB
> after
> I get a list of children?
>
see 1st note about a better method.
> 4) If one of my child People EJBs cannot have a new bonus applied (due to
> some
> other business rule) will/can all of the other object changes be rolled
> back?
>
yes, your update is atomic (ACID rules will be followed or you need
to switch containers).
> 5) One of the major strengths of the EJB framework is the concept of
> transactions. Are there any online resources to learn more about how these
> work?
>
JDBC spec. TPC specs.
> Thanks,
> jim
>
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