We have been doing this sort of thing with Maps and
CMP. We are using TOPLink which has now been bought or
licensed from The Object People by WebGain.
It is a little steep, but the development productivity
alone is worth it, plus it has some very advantageous
runtime performance benefits.
Nicholas
--- [EMAIL PROTECTED] wrote:
> Hello,
>
> does anybody know how (and if is it
> possible) to store
> lists,trees,hashtables... using EJB and representing
> a tree, a list.. with
> an EJB? For example, when I've tried to do it with
> this CMP Entity Bean,
> the
> EJB server said me "I don't know how to map my_list
> to database" (I'm using
> WebLogic 5.1):
>
> class MyEJBLinkedList implements EntityBean
> {
> public Integer PK_MyEJBLinkedList;
> // The Primary Key
> public java.util.LinkedList my_list;
> // This is a
> Serializable object!!
>
> // The functions here are not
> important, the are very
> simple.
> }
>
>
> --------------------
> The problem is that the container can't save the
> hashtable straight into
> the database as it is. Depending on the column type
> you have chosen for
> this particular member.
>
> This is database specific usually. If you use
> cloudscape, the db server has
> the possibility to serialize the hashtable into the
> database. More "normal"
> databases such as Oracle and such, do not have this
> possibility and you
> have to serialize the hashtable yourself in the
> ejbStore and ejbLoad
> method.
>
> The best way however is to implement it as an BMP
> and build the hashtable
> yourself.
> Regards
> Erik Romson
>
>
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