Typed event channels overview

[Martin Baulig <martin home-of-linux org>]

Hello,

I got some very first version of the typed events stuff working - and it's
already late at night, so just a few notes:

* you may need to start

  [gnome-debug/sesion-manager] ./gdf-session-manager --activate-goad-server gnome_debugger_session_manager --disable-crash-dialog

  by hand, for some reason it core dumps sometimes when started automatically

* after that, start

  [ggdb/commander-factory] ./gdb-guile-program-factory --activate-goad-server gnome_debugger_program_gdb_guile_factory

  in another xterm (to see the debugging messages).

* and finally, we use the gnome-debug/guile/test.scm to actually start
  the commander and send the event:

  [gnome-debug/guile] guile -l test.scm

=============================================================================

Basically, this `test.scm' does all the work for us:

----
(use-modules (gnome debugger))
(define manager (gnome-debugger-session-manager-init '()))
(define id (gnome-debugger-session-manager-create-session manager "gdb-guile" '("gdb-guile")))
(define program (gnome-debugger-session-manager-activate-session manager id))
(gnome-debugger-program-execute program '("foo" "bar"))
-----

It does the session manager stuff, gets a GNOME_Debugger_Program object
and then calls GNOME_Debugger_Program_execute ().

The actual typed event channel stuff is done in
impl_GNOME_Debugger_Program__create ():

----
    newservant->typed_event_channel = 
	goad_server_activate_with_id (NULL,
				      "gnome_debugger_typed_event_channel",
				      0,
				      NULL);

    fprintf (stderr, "Got typed event channel %p\n",
             newservant->typed_event_channel);

    newservant->typed_supplier_admin =
        CosTypedEventChannelAdmin_TypedEventChannel_for_suppliers
        (newservant->typed_event_channel, ev);

    fprintf (stderr, "Got typed supplier admin %p\n",
             newservant->typed_supplier_admin);

    newservant->typed_consumer_admin =
        CosTypedEventChannelAdmin_TypedEventChannel_for_consumers
        (newservant->typed_event_channel, ev);

    fprintf (stderr, "Got typed consumer admin %p\n",
             newservant->typed_consumer_admin);

    newservant->typed_proxy_push_consumer =
        CosTypedEventChannelAdmin_TypedSupplierAdmin_obtain_typed_push_consumer
        (newservant->typed_supplier_admin, "program-events", ev);

    fprintf (stderr, "Got typed proxy push consumer %p\n",
             newservant->typed_proxy_push_consumer);

    typed_consumer =
        CosTypedEventChannelAdmin_TypedProxyPushConsumer_get_typed_consumer
        (newservant->typed_proxy_push_consumer, ev);

    fprintf (stderr, "Got typed push consumer %p\n", typed_consumer);

    repo_id = CORBA_TypeCode_id (&TC_GNOME_Debugger_ProgramEvents_struct, ev);
    
    correct = CORBA_Object_is_a (typed_consumer, repo_id, ev);

    fprintf (stderr, "CORBA_Object_is_a (%p,%s) = %d\n",
             typed_consumer, repo_id, correct);

    if (correct)
        newservant->program_events_object =
            (GNOME_Debugger_ProgramEvents) typed_consumer;
----

We'll end up having a GNOME_Debugger_ProgramEvents object which is defined
like this:

----
        interface ProgramEvents {
	    void execute (in long serial, in arg_list args);
	    oneway void execute_response (in long serial, in Process process);
	    oneway void execute_error (in long serial, in string error_message);
	    oneway void execute_timeout (in long serial);
        };
----

Now, impl_GNOME_Debugger_Program_execute () sends a typed event by
calling

----
    GNOME_Debugger_ProgramEvents_execute (servant->program_events_object,
                                          1, args, ev);
----

After that, it should wait for a `execute_response' or `execute_error'
event on the channel, but that's not yet written.

=============================================================================

Currently, GNOME_Debugger_ProgramEvents_execute () will end up in a function
like this:

----
static void
impl_GNOME_Debugger_ProgramEvents_execute (impl_POA_GNOME_Debugger_ProgramEvents * servant, CORBA_long serial, GNOME_Debugger_arg_list * args, CORBA_Environment * ev)
{
   GNOME_Debugger_PrivateProgramEvents_execute buf;
   CORBA_any any;

   buf.serial = serial;
   buf.args = *args; /* fixme: refcounting */

   any._value = &buf;
   any._type = (struct CORBA_TypeCode_struct *)
       &TC_GNOME_Debugger_PrivateProgramEvents_execute_struct;
   CORBA_any_set_release (&any, CORBA_FALSE);

   fprintf (stderr, "impl_GNOME_Debugger_ProgramEvents_execute - %p - %ld - %p\n",
	    servant, serial, args);

   CosEventComm_PushConsumer_push (servant->push_consumer, &any, ev);
}
----

But this is only a temporary solution until we have a better marhalling/
demarshalling concept which will create stubs like this automatically
(and we won't need the temporary GNOME_Debugger_PrivateProgramEvents_*
structures).

-- 
Martin Baulig - martin@home-of-linux.org - http://www.home-of-linux.org