I'm attempting to convert an RMI Factory based program to EJB.
I have a table (FUND_DETAIL) of data that looks like this:
ID YEAR APPAMT OBLAMT DESCRIPTION
=== ==== ====== ====== ===========
315 1997 20 20 Secret Fund
315 1998 15 8 Secret Fund
315 1999 8 0 Secret Fund
220 1998 15 15 Special Fund
220 1998 10 6 Special Fund
Each row in this table represents an object called FundDetail, and I have
implemented this as an EJB. It seems to fit all of the criteria and it has a
significant number of business methods associated with it.
The interesting twist is I have need for another object that represents a
Fund at a higher level. This object is identical to the FundDetail class
without the presence of a year. Most of the amounts are summed. The data for
this object (Fund) would look like. I don't really have a table for this
object, this is just for clarification:
ID APPAMT OBLAMT DESCRIPTION
=== ====== ====== ===========
315 43 28 Secret Fund
220 25 21 Special Fund
I have thought of various designs for this relationship, and I would like to
pick the collective brain (ouch) of this newsgroup for EJB-friendly
representations.
Here are some of the thought processes I have considered.
Fund as an Entity Bean
======================
This didn't seem prudent as the Fund object doesn't represent a row in a
database. Furthermore, a user will create a new Fund by creating a new
FundDetail (with a year). If Fund was an entity with it's own database
table, I would have to enforce referential integrity in my FundDetail's
ejbCreate and ejbRemove methods which seems, at the very least, a great
performance drag. Is there a way for Fund to be an Entity without its own
database table?
Fund as a Stateless Session Bean
================================
This is the way I am leaning right now. The user would request the AppAmt
for a Fund, and a database query would result in the correct summary
information. It just seems kludgy to me, since the table is not normalized
at the fund level, and a change to description would result in a multiple
row update.
Fund as an Entity, FundDetail as a dependent
=============================================
A little more radical. I would be responsible for syncing the FundDetail
object. I could still use the FundDetail table, and CMP would be out of the
question.
I'd be interested in other options as well. What do you think?
jim
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