Re: Session Replication

From: Mike Kienenberger (mkienen..mail.com)
Date: Wed May 05 2010 - 17:27:39 EDT

  • Next message: Mike Kienenberger: "Re: Session Replication"

    I did find some tests written which explicitly serialized DataContext.
    Apparently I was serializing DataContext at one point, and had some
    issue where creating a data object, then deleting that data object
    without committing, and it was causing an issue with serialized
    DataContexts.

    On Wed, May 5, 2010 at 5:10 PM, Mike Kienenberger <mkienen..mail.com> wrote:
    > Hmm.   Unfortunately, I can't remember if my issue with that project
    > was that the DataContext wasn't being serialized or that it was and I
    > didn't want it to.  And this was 1.2, so the behavior may have changed
    > since then.
    >
    > But in either case, it seems pretty trivial.
    >
    > In the case of it being serialized, it already does what you want
    >
    > In the case of it not being serialized, you'd create a new DataContext
    > and dump in all of the serialized objects you had from the original
    > DataContext.
    >
    > I don't think there's any state that needs to be saved for a
    > DataContext other than the DataObjects it contains.   Maybe you'd also
    > need to save the initial fetched object snapshots if you were working
    > with optimistic locking.
    >
    > All I can say for sure is that I did a JSF project where we saved the
    > uncommitted DataObjects out as client-side data (serialized into the
    > generated html), then read them back in on the next request.   The
    > data would survive application restarts, so it should be equivalent to
    > moving it to another session or another server.
    >
    > I tried glancing through what project source code I had laying around,
    > but I couldn't find the code that dealt with the serialization -- too
    > many project modules to look through.
    >
    > On Wed, May 5, 2010 at 4:57 PM, Michael Gentry <mgentr..asslight.net> wrote:
    >> My experience with Tapestry (4 & 5) serializing a DataObject to the
    >> HTML (which it does by default when you have a loop in a form) is that
    >> the deserializing of the DataObject (on the subsequent
    >> request/response) gives you a DataObject that is disassociated from
    >> the DataContext (not good).  Perhaps if the DataContext went along for
    >> the ride all would be well ...
    >>
    >> Thanks,
    >>
    >> mrg
    >>
    >>
    >> On Wed, May 5, 2010 at 4:53 PM, Mike Kienenberger <mkienen..mail.com> wrote:
    >>> No direct experience, but I know you can serialize DataObjects and I'm
    >>> 99% certain you can serialize DataContexts.   I think I did this in
    >>> one project in the past to preserve state between requests rather than
    >>> saving state in the sessions.
    >>>
    >>> On Wed, May 5, 2010 at 4:37 PM, Michael Gentry <mgentr..asslight.net> wrote:
    >>>> Someone on another project here asked me if Cayenne works with session
    >>>> replication (with 1+ user DataContext objects in the HttpSession)
    >>>> between application servers (such as JBoss).  They have a project
    >>>> where they are running N instances of JBoss and they replicate/sync
    >>>> the session data across the JBoss instances.  They are curious if the
    >>>> DataContext + DataObjects will replicate correctly.  I've never
    >>>> attempted to do so and am not sure.  Does anyone have experience with
    >>>> this?
    >>>>
    >>>> Thanks!
    >>>>
    >>>> mrg
    >>>>
    >>>
    >>
    >



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