Why does the container emit a "Failed to create Python object" message when I try activating my component?

The simple answer is because for some reason or another the Python container is unable to create the component based on the information found in $ACS_CDB/MACI/Components/Components.xml (or from a dynamic component client).

Some of these reasons include but are not limited to:

• the Code attribute specifying the Python package and class for the component defined in Components.xml is incorrect
• the Type attribute specifying the interface repository location of the component's IDL interface defined in Components.xml is incorrect
• the constructor of your Python implementation of the IDL interface takes parameters when it should not
• the constructor of your Python implementation of the IDL interface raises any exception
• the Python CORBA stubs for your IDL interface are not in your $PYTHONPATH environment variable. There is a very high probability this is the case if the IDL module (i.e., namespace) your IDL interface is defined in is reopened in other ALMA CVS modules. See ALMASW2002083 in the ALMA SPR system for more details.
• the component baseclass(es) and/or container cannot find a definition for your component's IDL type within the CORBA IFR. If you see an error message complaining about some derivation of the word interface such as:

Traceback (most recent call last):
 File "../lib/python/site-packages/Acspy/Container.py", line 238, in activate_component
 File "../lib/python/site-packages/IERSImpl/IERS.py", line 60, in initialize
   addProperty(self, "dUT")
 File "/alma/ACS-4.1/ACSSW/lib/python/site-packages/Acspy/Util/BaciHelper.py", line 128, in addProperty
   interf = interf._narrow(CORBA.InterfaceDef) 

this is most definitely the case. Typical causes of this are failure to install your module into an $INTROOT before issuing the acsStart command. Additionally, it's possible that some bad IDL (i.e., interfaces declared twice, enum values declared twice in the same namespace, etc) has corrupted the Inferface Repository. Please pay very close attention to the output coming from acsStart if you think this may be the case. To verify that this type of error is occuring, simply start ACS and run the irbrowser command to see if your IDL interface is really loaded into the CORBA interface repository.

Also, if you're running the Python container from the acscommandcenter you're not seeing the entire output of the container (temporarily at least) and more importantly the underlying error message from the Python interpreter. Try starting the container from the command-line instead. See FAQ on Delayed Output for more details.

-- DavidFugate - 06 Aug 2004