Re: lifecycle callbacks and ROP

From: Andrus Adamchik (andru..bjectstyle.org)
Date: Sat Mar 10 2007 - 10:42:45 EST

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    On Mar 10, 2007, at 2:15 AM, Aristedes Maniatis wrote:

    >
    > On 10/03/2007, at 10:13 AM, Tore Halset wrote:
    >
    >> Hello.
    >>
    >> I am a lifecycle callbacks newbie trying to understand http://
    >> cwiki.apache.org/CAYDOC/lifecycle-callbacks.html in a ROP context.
    >>
    >> Can the callback methods be defined in the client PersistentObject
    >> or only in the server CayenneDataObject?
    >
    > I believe that they will only operate on the server side. At least
    > that's how we've been able to use them.

    True. Let's put it this way - no decision has been made on the client
    callbacks yet.

    >> Can a ROP client perform non-lifecycle callbacks on the server? If
    >> not, are there any other standard way for a ROP client to call a
    >> method on the server not related to the persistence lifecycle?
    >
    > We use Jetty as the transport for Hessian between client/server
    > ROP. So we can define special servlet calls as we need in order to
    > perform code on the server or return values. For instance, when a
    > client logs into the server we wanted the server to maintain a list
    > of client sessions. So, because we aren't committing an object
    > through Cayenne to the server we couldn't use a lifecycle event and
    > we wrote a special servlet call which is used instead.

    IIRC, Tore mentioned this before, that it would be nice to define
    some arbitrary RPC-like calls to the server-side peer objects, kind
    of like EOF does. So that you can do clientObject.doX() and it will
    proxy the call to the serverObject.doX(). I'd say this can be a new
    feature in 3.0, and it would be nice if somebody volunteers to do it.

    Andrus



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