[omniORB] omniORBpy newbie: returning interface from remote call

[gabriele renzi]

Hi everyone,

I just started experimenting with omniORBpy today,
everything seemed to be working fine but now I hit a
strange problem. My IDL file looks like this

module PSD {
interface Calc {
string myop(in string name,in string other);
};
interface CalcFactory {
Calc client_instance(in string cname);
};
};
omniidl seems to compile the idl fine, and I can get
the CalcFactory correctly via
obj= orb.string_to_object(ior)
cf = obj.narrow(PSD.CalcFactory)

but then if I try to call
calc = cf.client_instance('name')
I get a
CORBA.BAD_PARAM(omniORB.BAD_PARAM_WrongPythonType,
CORBA.COMPLETED_MAYBE) exception.

The code in CalcFactoryImpl, the subclass of the
abstract PSD__POA.CalcFactory is like this:
def client_instance(self,key):
client=CalcImpl() # PSD__POA.Calc subclass
return client

Someone has a clue on what I may be doing wrong? Sorry
if I'm posing a dummy question.


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[Duncan Grisby]

I just started experimenting with omniORBpy today, everything seemed
to be working fine but now I hit a strange problem. My IDL file looks
like this

[...]

but then if I try to call
calc = cf.client_instance('name')
I get a
CORBA.BAD_PARAM(omniORB.BAD_PARAM_WrongPythonType,
CORBA.COMPLETED_MAYBE) exception.
The code in CalcFactoryImpl, the subclass of the
client=CalcImpl() # PSD__POA.Calc subclass
return client

client is a servant, i.e. a programming language object. It is different
from a CORBA object reference, which is what you must return from your
factory operation.

To get an object reference, you must activate your servant in a POA. In
your simple example, you can activate it in the RootPOA and return an
object reference with a call to _this():

def client_instance(self,key):
client=CalcImpl() # PSD__POA.Calc subclass
return client._this()

In general, you should learn about POAs and their policies, otherwise
you'll be bitten by object lifecycles sooner or later. Ciaran McHale has
written a good free book that explains it all very well. Take a look
here:

http://www.ciaranmchale.com/corba-explained-simply/

and especially this chapter:

http://www.ciaranmchale.com/corba-explained-simply/concepts-for-server-side-programming.html

The slides and code for a tutorial I gave might be useful for you too:

http://www.grisby.org/presentations/py10code.html


Cheers,

Duncan.

[gabriele renzi]

Post by gabriele renzi

Post by gabriele renzi
I just started experimenting with omniORBpy today,

everything seemed

Post by gabriele renzi
to be working fine but now I hit a strange

problem. My IDL file looks

Post by gabriele renzi
like this

[...]

Post by gabriele renzi
but then if I try to call
calc = cf.client_instance('name')
I get a
CORBA.BAD_PARAM(omniORB.BAD_PARAM_WrongPythonType,
CORBA.COMPLETED_MAYBE) exception.
The code in CalcFactoryImpl, the subclass of the
client=CalcImpl() # PSD__POA.Calc subclass
return client

client is a servant, i.e. a programming language
object. It is different
from a CORBA object reference, which is what you
must return from your
factory operation.

yes, I got it in the end, I just expected that this
would have been done by the implementation instead of
me for what relates to method calling.

Thanks a lot for all the links they seem quite useful
and interesting :)



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