Re: ObjectStore and Caching

From: James Treleaven (jametre..noreo.on.ca)
Date: Fri Jan 09 2004 - 20:05:23 EST

  • Next message: Andrus Adamchik: "Re: ObjectStore and Caching"

    Hi Andrus,

    Thanks very much for your response.

    I really need to know two more things though:
    1) Can I turn Level 1 caching off? I certainly hope so!
    2) If I can - how do I do it?

    cheers,
    James

    Andrus Adamchik wrote:
    >
    > On Jan 9, 2004, at 6:19 PM, James Treleaven wrote:
    >
    >> Hi
    >>
    >>
    >> I am looking at deploying my webapp which uses Cayenne across a
    >> cluster of webservers, and I just want to make sure I don't get bitten
    >> by Cayenne's caching architecture.
    >>
    >> My understanding is that Cayenne currently does caching within a
    >> single Java VM, and that the intention is to provide cross VM caching
    >> in the 1.1 release:
    >> http://objectstyle.org/jira/secure/ViewIssue.jspa?key=CAY-30
    >>
    >> Is single-VM caching turned on by default? If so, does this mean that
    >> if I deploy my Cayenne app across a cluster I will run into problems?
    >>
    >> thanks,
    >> James
    >
    >
    > Hi James,
    >
    > Let me explain current and future levels of caching in Cayenne. When I
    > am talking about DataContexts/DataDomains below, this assumes whatever
    > helper objects they are using for caching (e.g. ObjectStore). More
    > detailed documentation will be included in 1.1.
    >
    > Level 1 - No Cache Sharing: DataContext keeps its own cache - whatever
    > is fetched from the database via a DataContext is never shared with
    > other local or remote DataContexts. Changes made on commit are not
    > propagated to other DataContexts.
    >
    > Level 2 - Local VM Cache Sharing: Each DataDomain keeps the cache shared
    > by all DataContexts in the same VM. Changes made via one of the
    > DataContexts are automatically shared by other DataContexts in the same VM.
    >
    > Level 3 - Distributed Cache Sharing: Behaves just like Level 2, but also
    > synchronizes caches of DataDomains with the same name across JVMs.
    >
    > Cayenne 1.0.* implements Level 1 only, i.e. no sharing of cache either
    > locally or remotely. Cayenne 1.1 will have all three levels supported,
    > configurable via CayenneModeler. Ideally no application code changes
    > will be required to switch between the levels. Also this means that 1.1
    > is fully backwards compatible with 1.0.
    >
    > Hope this answers your questions.
    >
    > Andrus

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