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From Marco Schulze <Ma...@NightLabs.de>
Subject Re: makePersistent detached instance deleted on database
Date Wed, 08 Mar 2006 16:05:44 GMT
Erik Bengtson wrote:
>What happens when we invoke makePersistent on a detached instance that was
>deleted by another isolated process? I suspect that we raise an exception
>instead of reinserting it for a second time. Is that right?
>Maybe this can be clarified in the spec.
Hello JDO team,

we have the following situation, which IMHO Erik is refering to:

We have multiple datastores where each datastore belongs to one 
organisation (e.g. company). In order for the organisations to do 
business with each other, they need to exchange data. Thus, all our JDO 
objects are owned by one datastore and have the organisationID of this 
datastore as part of their composite PK (we are using exclusively 
application identity).

Now, say organisation B wants to become a reseller for organisation A 
concerning their ProductType Mercedes320E. This causes the object graph 
of the Mercedes320E (including price configuration and a lot of other 
data) to be copied from datastore A to datastore B. Of course, some of 
the objects within this graph (e.g. the currency EUR) already exist in 
datastore B and some don't (e.g. the currency $). The ones that don't 
exist yet must be added - the ones that are already there need an update.

After this initial copy, the copied object will be updated whenever the 
object graph is modified in the original datastore. Until now, as well 
for the initial copying as for the updates, I simply detached my 
ProductType from datastore A with all the necessary fetch-groups and 
attached it in datastore B. This was simply adding/overwriting all the 
data within the object graph and that's basically the behaviour I need.

I hope I could explain the situation well enough.

Best regards,

Marco Schulze
NightLabs GmbH
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Marco Schulze                   NightLabs GmbH
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                                79100 Freiburg

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WWW:    http://www.NightLabs.de

  Marco Schulze <Marco@NightLabs.de>
  Niklas Schiffler <Nick@NightLabs.de>

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