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From "Christophe Lombart" <christophe.lomb...@gmail.com>
Subject Re: How can aggregation be mapped in OCM?
Date Tue, 05 Sep 2006 14:24:39 GMT
On 9/5/06, Dan Connelly <dsconnelly@adelphia.net> wrote:
> Christophe:
>
> Okay.   But it does get a little tricky, as follows:
>
> ReferencingBeanConverterImpl#insert operation:   This must actually
> create a node for the bean if there is no node for its already.   If the
> bean has a node (elsewhere),  then a reference node is inserted
>

If I remember correctly, a referencable node matches to a JCR property
in the target node.
Why to create subnode ? Sorry if  I'm wrong because I have not all the
details on the JCR spec. I have to review it.


> ContainedBeanConverterImpl#insert operation.   This must move the node
> if it already exists elsewhere, leaving a reference node in its
> place.    Otherwise, it creates and inserts the node for the bean.
>
What do you mean by moving the node if it is already exist. How to
check if it is the same node ? I don't understand all the details
here. Can you give more information ?

> Is this what you are suggesting?
>
>        -- Dan

Without some use cases, it is difficult to gives exact information but
here are some thoughts on JCR references. This is just to start some
discussions because I don't know if we have to implement the same
features.

Precondition to map a jcr referenceable node to a bean
--------------------------------------------------------------------------------
* The referenceable node already exists in the repo (of course based
on mix:referencable).
* If I remember correctly the JCR spec : the reference is stored in a
property in the target node.

Mapping file
------------------
We have to check how to specifiy the references in the mapping file.
We should support references from a bean descriptor but also from a
collection descriptor. I mean it should be possible to create a
collection containing some references to other nodes (objects).

If we accept this situation, we have to find a way to

1/ [When retrieving the object containing the reference] : Map a JCR
node property to a java bean and in the case of a collection of
references, a series of JCR node properties into a Java collection (or
map).

2/ [When updating, inserting the object containing the reference] :
Map a bean attribute into a JCR property (UUID value) or a collection
attribute into a serie of JCR properties.

Let me know if I'm wrong because I don't remember all the details from JCR spec.
We have also to check how to avoid some performance issues (is it
possible to use the existing features like proxy, auto-retrieve,
auto-update, ...).

Ohoh It is more than I expected 2 days ago :-(


Christophe

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