Re: Event Server, Callbacks, ...

[dthompson characterlink net (Darrin Thompson)]

Read specifically about push consumers. The client is listening. The 
function for handling the event in the client is a "callback" from the 
event channel.

Darrin

>>>>>>>>>>>>>>>>>> Original Message <<<<<<<<<<<<<<<<<<

On 10/19/00, 12:33:20 PM, Marcelo CB <corbani async com br> wrote regarding 
Re: Event Server, Callbacks, ...:


> Thanks a lot.

> There is a bit I still don't get ... shouldn't I have
> 'someone listening' to the event push from the server ?

> What I mean is that at server side I leave control to the
> CORBA_ORB_run() which takes care of listening and handling client
> requests. But at client side, who will be listening  to it, since I
> control the main ( and only ) thread of execution ? What if I want to use
> GTK and leave control to gtk_main() ?


> On Thu, 19 Oct 2000, Darrin Thompson wrote:

> > Here are some possible solutions:
> >
> > If you used an event server (TAO has a standalone one that should work
> > fine with ORBit) you could do this:
> >
> > Server object is a push supplier to the event service.
> >
> > Client objects are push consumers of the event service.
> >
> > When a change happens:
> >
> > Server object pushes an event with information about a change.
> >
> > Client objects all receive the event.
> >
> > Client objects all take action as soon as they receive the event.
> >
> > ******
> > You can get around the lack of event service by doing this:
> >
> > Server object has a "register" method.
> >
> > Clients also implement a "receive notification" object.
> >
> > At client startup:
> >
> > Client creates the receive notification object. Client calls the servers
> > "register" method with a reference to the notification object.
> >
> > When a change happens:
> >
> > The server calls a method on all the receive notification objects it
> > knows about. This is kind of a pain because some of the objects may have
> > died mysteriously with their clients.
> >
> > Hope this drivel helps.
> >
> > Darrin
> >
> > >>>>>>>>>>>>>>>>>> Original Message <<<<<<<<<<<<<<<<<<
> >
> > On 10/19/00, 9:08:52 AM, Marcelo CB <corbani async com br> wrote regarding
> > Event Server, Callbacks, ...:
> >
> >
> > > In an application I'm implementing I have a server object holding a
> > > frequently changed list, and I need the clients to be warned when changes
> > > happen to the list.
> >
> > > It seems to me at first that I need something like an event-server, (
> > > unavailable in ORBit ) but it is still unclear to me how would my client
> > > 'be warned' of the changes.
> >
> > > I thought the solution would be to have something like a server
> > > thread in each client ( ORBit-mt ? ) and a client within the server ( the
> > > list server itself ) to make the messaging delivery.
> >
> > > As you see, the thing is kind of messy in my head, and though I read the
> > > Event Server chapter in the 'Advanced CORBA Programming ', the OMG spec
> > > for the event services, and read some things Wilhelmi wrote, I seem not
> > to
> > > get it.
> >
> > > Maybe I'm just too dumb and need some help.
> >
> > > --
> > > Marcelo Corbani de Barros                   corbani async com br
> > > Async Open Source Development - Brasil
> >
> >
> > > _______________________________________________
> > > orbit-list mailing list
> > > orbit-list gnome org
> > > http://mail.gnome.org/mailman/listinfo/orbit-list
> >
> > _______________________________________________
> > orbit-list mailing list
> > orbit-list gnome org
> > http://mail.gnome.org/mailman/listinfo/orbit-list
> >

> Marcelo Corbani de Barros                   corbani async com br
> Async Open Source Development - Brasil


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