CORBA 2.6 Programmer's Guide for C++

Appendix C. Servant Reference Counting in NonStop CORBA
Appendix C. Servant Reference Counting
in NonStop CORBA
The OMG specification for CORBA 2.6 defines two options for servant reference counting:
Reference counting using the RefCountServantBase mix-in class●
No reference counting●
The NonStop CORBA 2.6 product supports both these options and adds a third: reference counting
within the CORBA::Object associated with the servant. This option provides backward compatibility
with earlier versions of the NonStop CORBA product (then called NonStop DOM).
The ORB can detect whether or not the servant is derived from RefCountServantBase. If so, then
the application is using OMG standard reference counting. If not, then the application is using
CORBA::Object reference counting (the default). Therefore, a properly working NonStop DOM 2.0
servant will work as expected under CORBA 2.6 because, by default, CORBA 2.6 is backward
compatible with NonStop DOM 2.0.
If your application is using no reference counting at all for a servant, the servant must override the
method Servant::_uses_which_ref_type() with an implementation that returns a value of
zero.
NSDOM_ServantBase::NSDOM_Ref_Type
NSDOM_ServantBase::_uses_which_ref_type()
{
return Uses_NSDOM_ref_count;
// must be overridden by OMG compliant programs which do not use
// reference counting.
}
void
NSDOM_ServantBase::_add_nsd_ref()
{
if (_uses_which_ref_type() == Uses_NSDOM_ref_count)
{
CORBA::Object::_duplicate( this->_this_reference() );
} else
this->_add_ref();
}