Re: [Orbit-python-list] (in Object obj) marshalling error

[Jason T. <ta...@li...>]

> So I'm passing as a parameter a Python Object which I've just instantiated
> from a class that inherits from a __POA class, so it _is_ a Corba Object.

As Roland pointed out, Foo is a Python object, not derived from the
__POA class.  ORBit-Python has no idea what to do with that object, even
if it weren't broken. ;)

Basically ORBit-Python doesn't seem to handle generic object references
very well (at all) right now.  I made a change to my local copy that
_seems_ to correct the problem, but the change was so trivial that it
can't possibly be right, so I'll want to test it a little further before
I commit it.

> According to the CORBA Python Mappings,
> 
>  	If an operation expects parameters of the IDL Object type, any
> 	Python object representing an object reference might be passed as
> 	a value.

I think you might have misunderstood what this says, or maybe it's a
little ambiguous.  A Python object representing an object reference
looks like:

   class Foo(CosNaming__POA.NamingContext):
      pass
   a = Foo()
   a._this() # implicit activation
   ref = poa.servant_to_reference(a) 
   # ref is a python object that represents the object reference
   print ref

Yields:

   <CosNaming.NamingContext object at 80e2518>

I don't think the mapping specification says that in your example
bind(1) should work.  1 is not a CORBA object.  I think, though, it
might be a nice feature if ORBit-Python coerced servants into object
references in this situation.

> A different message, for the same reason? What I mean is that _any_ object
> that I pass - be it local, Corba, or simple number/string objects get me

No, a different message for a different reason.  I'll go through your
examples from your original email and explain what happened:

> 1) Calling bind with a simple object reference:

> [...]
> class Foo:
>    pass
> a=Foo()
> nc.bind(a)
> TypeError: Failed to marshal: Object Reference ()

Like I said earlier, ORBit-Python doesn't handle generic object
references.  However, even if it did, this wouldn't work because Foo
doesn't inherit a POA class.

> 2) Didn't work? Ok, let's try a stringified IOR:
> nc.bind(orb.object_to_string(a))
> CORBA.SystemException: IDL:CORBA/MARSHAL:1.0: IDL:CORBA/MARSHAL:1.0

I'm not entirely sure what happened here, but my guess is 'a' wasn't a
valid IOR (such as, for example, if it has trailing newlines and you're
not using the latest CVS version).

This exception was probably raised from object_to_string, not within
the bind stub.

> 3) Let's do something dumb now:
> nc.bind(1)
> TypeError: Failed to marshal: Object Reference ()

Well again, ORBit-Python won't handle the objref properly, but in this
case you're not passing it a CORBA object.  It sounds to me like you're
mixing up the Any type with the Object type. 

> 4) And what about
> nc.bind(orb.object_to_string(1))
> Segmentation fault

Okay, well this is a bug in ORBit-Python, to be sure.  ORBit-Python's
object_to_string doesn't do any sanity checking.  ORBit-Python happily
passes this over to ORBit, which in turn happily tries to dereference
this value (thinking it is a CORBA_Object) and kaboom.

This is documented actually in the source code, in CORBA_ORB.c:

   if (PyArg_ParseTuple(args, "O", &obj)) {
      // validate obj == CORBA_PyObject
      s = CORBA_ORB_object_to_string(self->obj, obj->obj, &self->ev);
 [ ... ]

It's just missing a FIXME :)

So, here the segfault happens inside object_to_string, not bind().

Anyway thanks for identifying this bug.  I'll hopefully commit some sort
of fix by the end of the day. :)

Jason.