RE: Business Objects vs Data Objects [was Re: JXTemplates -what' s in a name?]

[Derek Hohls <DH...@csir.co.za>]

Antonio

Thanks, this is great - maybe we can open a Wiki
page and add this as an attachement (maybe refine
it to make a little more generic; or have a general
version and then variants for more speciifc cases).

2 questions - 

a. I assume Hibernate can be used in place
of JDO (and is it any better?) 

b.  What are "transient" objects??  and what is their
role in the whole picture?

Thanks
Derek

>>> agallardo@agssa.net 2004/05/07 09:01:59 AM >>>
Derek Hohls dijo:
> Yes; this confused me too - are there now:
> DAO - used to read data from DB
> DTO - to transfer data to app
> BO - to store/manipulate data for a particular "thing"
>
> and how do any/all these interrelate with each and
> the Forms framework...
>
> If someone can post a reasonably clear explanation of
> all this, with links to examples/references, I think its
> worth adding at least to Wiki, if not the main docs.

Hi Derek:

It is almost a year old graph, a very simple one, but maybe it can help
to
provide a big picture. The names are not the best as we are learning
with
the time, but maybe can help a little:

http://marc.theaimsgroup.com/?l=xml-cocoon-dev&m=105955717614416&w=2 
(See the png attached).

I hope this help.

Best Regards,

Antonio Gallardo

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RE: Business Objects vs Data Objects [was Re: JXTemplates-what' s in a name?]

[Antonio Gallardo <ag...@agssa.net>]

Derek Hohls dijo:
> Antonio
>
> Thanks, this is great - maybe we can open a Wiki
> page and add this as an attachement (maybe refine
> it to make a little more generic; or have a general
> version and then variants for more speciifc cases).
>
> 2 questions -
>
> a. I assume Hibernate can be used in place
> of JDO (and is it any better?)

Yep.

<RT>
BEAWARE: I am far to be a guru in this area.

Currently, I found myself asking about the "viability" of using EJB for
the overall task in some applications. Recently, Ralph's posts, triggered
in my mind the idea of how will be the best approach to use J2EE (that
include EJB) with Cocoon. I read some articles about that too. And there
are diferent approach. Some articles tell you that Cocoon need to be used
just as a publishing framework while using J2EE. But I think: This was
before flow. But, now we have Flow and I don't like the idea of stripdown
Cocoon wings when I know how much it can do and help.... Of course this is
a very large discussion and a interesting one.

What I understand is that you can use Hibernate, OJB or "JDO alone" inside
EJB. There is currently a BIG discussion about O/R mapping tools vs. EJB
CMP and I am on the JDO side. JDO is really great and simple seems to
simplify many complexity that EJB need in order to work. If this is true,
then the question is why we need to use EJB CMP in order to reach
scalability? Maybe I am wrong, but there MUST be another simple path to
this.... and JDO promise that. See:

http://www.theserverside.com/news/thread.tss?thread_id=25695
JDO website: http://www.jdocentral.com/

</RT>

> b.  What are "transient" objects??  and what is their
> role in the whole picture?

In short, in the for DB developers:

Transient Object: NOT stored on a Database. Not a DB Object.
Persistent Object: It is sotred on a Database. It is a DB Object.

A Formal description of the above:

Transient Object: A transient object exists only in the memory of the
process that creates it. When that process terminates, the transient
object ceases to exist. This is diferent from a persistent object:

Persistent Object: A persistent object is an object that continues to
exist and retains its data beyond the duration of the process that creates
it.

Best Regards,

Antonio Gallardo


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