Hi,
You may want to check Issue 74 of Object Modeling -- Historic Values
The strategy is not specific to EJB.
http://www.togethercommunity.com/coad-letter/Coad-Letter-0074.html
Ricardo Caetano
> -----Original Message-----
> From: Christophe Demez [mailto:[EMAIL PROTECTED]]
> Sent: Segunda-feira, 11 de Dezembro de 2000 13:22
> To: [EMAIL PROTECTED]
> Subject: Historisation of EJB attributes - Design Patterns - Complex ?
> Importance: High
>
>
> Hi,
>
> I have face a problem :
>
> I have severals EJB and I need to have an historic for
> severals attributes.
>
> I m searching for a solution that should be performant and generic.
>
> I have think to the following solution, maybe you have others ones.
>
> 1. The basic solution
> ----------------------
> Each attribute is modelised like a collection of attribute,
> each attribute
> has an associated date.
>
> I need to create methods like :
> getSalary(Date ...)
>
> setSalary(Date ...)
>
>
> 2. What are the problems
> -------------------------
> It sounds that each attribute is a collection of EJB, I want
> if possible
> minimize the number of EJB. But if I use serializable class
> the change on
> the attributes are not reflected to the remote Bean.
>
> Does I need to load all the collection to get the value of
> the attribute at
> a specific date.
> Yes, if I have an attribute at 10/10/2000 and the second at
> 20/10/2000, I
> need to scan the collection and :
>
> 1. I get at least the 2 values and by example I apply a average
> 2. I get the older one ( 20/10/2000 )
>
> So I need to put some management rules, maybe different for
> each kind of
> attribute.
>
> What I need
> ------------
>
> I m searching for THE optimal solution ( If exists ).
> My priorities :
> - Performance in term of access and memory
> - Flexibility in the design to add constraits and new features
> - Easy to use
>
> I hope that someone can help me
>
> Thanks a lot for your help.
>
> If you have faced the same problem and/or you have simple
> idea, feel free to propose it !!
>
> Christophe Demez
>
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