Re: Some design questions

From: Aristedes Maniatis (ar..sh.com.au)
Date: Sun Nov 18 2007 - 15:52:39 EST

  • Next message: Tarik: "Re: Some design questions"

    On 19/11/2007, at 6:57 AM, Tarik wrote:

    > I have been trying the cayenne ROP features and am considering using
    > it for
    > a project which requires multiple (swing) clients to connect to an
    > application server. I have got it to work for a simple example.
    > Now I have
    > some more design questions.

    We do much of what you describe in a client/server ROP application: http://www.ish.com.au/oncourse
    . You can download it and give it a try to see the user interface and
    I guess there isn't technically much to stop you poking around its
    class structure with a little decompiling :-)

    > - Can a client app register to listen for changes on server object?
    > Since
    > there will be multiple clients, I want changes made by one client to
    > appear
    > on the others without them having to refresh.

    There is a messaging framework in Cayenne, although in our case I've
    been thinking of doing something a bit different since we may have
    clients which aren't on the same subnet, so some sort of polling
    mechansim was what I was planning.

    > - I will need to create a number of JTables with data coming from the
    > server. Has anyone done some labor-saving work around automatically
    > displaying cayenne object data in a JTable? (It would be awesome if it
    > allowed traversing associations, adding /removing columns / applying
    > filters, etc.)

    We have. Perhaps we could discuss this further off list. I am a bit
    busy for the next 2-3 weeks what with a tender process, a large new
    customer migration, oh, and the birth of my daughter last week... she
    is very cute.

    > - What kind of locking does data context provide? say i have two
    > threads
    > updating an object and one commits first and stales the object.
    > What will
    > happen when the second thread tries to commit.
    > - Is there a know throughput limit in terms of transactions per
    > second with
    > the hessian web service?

    No limit really since Hessian is just a lightweight serialiser.
    Probably the limit is more in Jetty or whatever servlet container you
    are running, or perhaps in your database backend. We don't scale our
    application beyond about a dozen users, so our needs aren't huge. We
    chose Jetty mainly for its support in version 6 for a high rate of
    small transactions, plus it is very simple to use.

    Ari

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