Re: IDL->C mapping question

[Frank Rehberger <Frank Rehberger web de>]

Olivier Andrieu wrote:

> Frank Rehberger [Thursday 29 May 2003] :
> >
> > Olivier Andrieu wrote:
> > 
> > >Hi,
> > >
> > >I'm writing ORBit2 bindings for the programming language Objective
> > >Caml and while testing things a bit, I noticed that the
> > >CORBA::ORB::get_service_information operation returns a NULL pointer
> > >for an out value of type struct. 
> > >
> > >The IDL definition is :
> > >
> > >    boolean get_service_information (
> > >      in ServiceType service_type,
> > >      out ServiceInformation service_information);
> > >
> > Just a thought, might it be the case that the operation throws an 
> > exception? In this case the out value would be undefined.
>
>no, it does not throw an exception, it returns false and a NULL
>out_value. I guess it's kind of a bug in the interface, it would be
>better with a union as out value :
>
> union service switch (boolean) {
>   case TRUE:
>     ServiceInformation service_information;
> };
>  
>

as this operation belongs to ORB interface specified by OMG we can not 
change the signature or type declaration.

But, it seems you are right:
In case operation "ORB::get_service_information()" returns with 
CORBA_false, the reference to out value 'service_information' should 
point to some valid value, which must be CORBA_free'd by caller. In this 
case the pseudo operation 'get_service_information()'  would be 
consistent to remote operation calls.

The question is, which value should it point to?

The  OMG-CORBA-2.3 Spec. does not tell much about it:
-----------------------------------------------------------------
 
4.2.2 Getting Service Information
4.2.2.1 get_service_information
boolean get_service_information (
in ServiceType service_type;
out ServiceInformation service_information;
);
The get_service_information operation is used to obtain information 
about CORBA
facilities and services that are supported by this ORB. The service type 
for which
information is being requested is passed in as the in parameter 
service_type, the
values defined by constants in the CORBA module. If service information 
is available
for that type, that is returned in the out parameter 
service_information, and the
operation returns the value TRUE. If no information for the requested 
services type is
available, the operation returns FALSE (i.e., the service is not 
supported by this ORB).

--------------------------------------------------------------

Best regards, Frank