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POIs it possible to have remotely managed entities?
 

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  1. POIs it possible to have remotely managed entities?
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    <p>I'm not much familiar with JPA, but I have this scenario: I would like to use the same classes (read "code") on both the server and the client (Java SE) for KISS/DRY reasons. It seems to me that one possible way to do this would be to have a (special?) <code>EntityManager</code> on the client that passes requests for entities to the server and at the end passes all entities back to the server for a "batch persist action" where classes can (re-)validate their data, apply some transactional operations (updating and stuff) and be all persisted nicely by the JPA implementation.</p> <p>The question is: Is that possible? How? (is there already a solution for this? is it simple, of sorts, to solve this with "some" code?)</p> <hr> <p><strong>Edit:</strong> Ok, let me clarify a couple of things for everyone. My background is with an in-house grown application framework that uses what could be called generic persistence services; i.e. services for performing CRUD actions (one service per action for any table) within a single transaction but are backed by classes (within the service) that intercept these actions and offer validation and (often) complicated business rules (with updates to other tables, etc.). That was implemented with older Microsoft products. Now there is a shift to .NET where there have recently appeared similarly-working but more advanced frameworks like DevForce and CSLA. DevForce in particular offers what I'd like to also do in Java (see the "Executing on the client" paragraphs on <a href="http://drc.ideablade.com/xwiki/bin/view/Documentation/client-tier" rel="nofollow noreferrer">this page</a> and then visit <a href="http://drc.ideablade.com/xwiki/bin/view/Documentation/architecture-client-development" rel="nofollow noreferrer">this page</a> for a better overview).</p> <p>An older question of mine on this general subject: <a href="https://stackoverflow.com/questions/2023538/java-equivalent-to-csla">Java &quot;equivalent&quot; to CSLA</a></p>
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    1. COAnd how is this different from sending detached entities to the client, modify them, and then send them back to the server for re-attachment and persistence?
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      1. USEdwin Dalorzo
    2. CO@edalorzo That's what I'm saying, but... "management" is the key word. Since my classes are JPA-enabled, wouldn't it be "swell" to have an EntityManager on the client that has the added (?) ability to "pack-up" all those entities I've been working with and send them to an EntityManager on some server that can properly take care of persistence in one transactional swoop?
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    3. COI do not think I am understanding your scenario yet. From my standpoint the client should not even know that such thing as an entity manager exists. Correctly exposed through a business interface, the server could carry out all the work you suggest in a single transaction swoop when asked by the client and the entities would not even abandon the safety of the server. Having a persistence context per client must be a nightmare when it comes to concurrency. Depending on the level of concurrency every client is likely to become a stale cache in a very short time. Don't you think?
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