CORBA26 — Pbl: Improper mapping rule from IDL3 to IDL2 when dealing with events.

Dealing with the following IDL3 definition, a problem arises when
generating the IDL2 definitions (complete IDL2 mapping is enclosed at
the end of this mail).

module example {
valuetype AnEvent : Components::EventBase

;

component Producer

;

component Consumer

;
};

According to the chapter 5 of the CCM specification, the publishes
definition of the Producer component is mapped to the following
definition (excerpt).

interface Producer : Components::CCMObject

;

In the mean time, the consumes definition of the Consumer component is
mapped to the following definition.

interface Consumer : Components::CCMObject {

::example::ConsumerEventConsumers::AnEventConsumer
get_consumer_input();

};

We can see that two versions of the "AnEventConsumer" interface have
been defined in two distincts modules. Thus the following Java
lines are not correct:

example.Producer p = ...;
example.Consumer c = ...;

p.subscribe_output(c.get_consumer_input());

The Java compiler will refuse to compile the last one, producing an
error like "BadTypeCoerce". However, in the IDL3 definitions, both
components have been defined in order to be used together. (sic!)

Thus, we think that the mapping for a Consumer should not be based on
the component definitions, but on the event definition itself. It
would then avoid multiple (incompatible) definitions of the consumers.
This mapping could be defined in two distinct ways.

see below