Re: Singletons in Cayenne and problems. Can I use multiple transactions?

From: Andrus Adamchik (andru..bjectstyle.org)
Date: Tue Dec 01 2009 - 10:00:17 EST

  • Next message: Evgeny Ryabitskiy: "Re: Singletons in Cayenne and problems. Can I use multiple transactions?"

    On Dec 1, 2009, at 4:29 PM, Evgeny Ryabitskiy wrote:

    > It's a crutch :/

    Possibly. If we are to redesign public transaction API in Cayenne,
    let's looks at the big picture then and see what problems we are
    trying to solve. IIRC it was mentioned before that we can make
    *manual* transaction management more user-friendly (automatic is as
    friendly as it gets)... I am not sure how (or rather my ideas go in
    the direction of allowing attaching arbitrary objects to transactions,
    maybe not something you care about), but if you have ideas, let's
    discuss them.

    >> transactions, and while addressing one use case it breaks others
    >> (i.e. other
    >> users may need a single commit point across multiple DataDomains).
    >
    > Ok. Actually I has no differences between several domain-local
    > transactions and one huge that is across multiple DataDomains.
    > The question is Transaction is working well across multiple
    > DataDomains?

    There's nothing magical about Transactions. In Cayenne they are a
    store of JDBC Connection to ensure that multiple sub-operations within
    a given operation get the same connection and consequently operate on
    the same db data version.

    2 possible caveats between domains when they reuse transactions:

    * They should both use either external or internal transactions (i.e.
    the same transaction strategy).
    * If they want completely separate connections, DataNode names should
    not match. If they want to reuse connections from each other, they
    DataNode names should match.

    Andrus



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