11. Appendix

This section contains information that is referenced from other sections, and that does not really need to be read in sequence.

11.1. Special type names

This documentation uses a few special terms to refer to Python types:

string
a unicode string or a byte string
unicode string
a Unicode string type (unicode in Python 2, and str in Python 3)
byte string
a byte string type (str in Python 2, and bytes in Python 3). Unless otherwise indicated, byte strings in pywbem are always UTF-8 encoded.
number
one of the number types int, long (Python 2 only), or float.
integer
one of the integer types int or long (Python 2 only).
callable
a callable object; for example a function, a class (calling it returns a new object of the class), or an object with a __call__() method.
hashable
a hashable object. Hashability requires an object not only to be able to produce a hash value with the hash() function, but in addition that objects that are equal (as per the == operator) produce equal hash values, and that the produced hash value remains unchanged across the lifetime of the object. See term “hashable” in the Python glossary, although the definition there is not very crisp. A more exhaustive discussion of these requirements is in “What happens when you mess with hashing in Python” by Aaron Meurer.
unchanged-hashable
an object that is hashable with the exception that its hash value may change over the lifetime of the object. Therefore, it is hashable only for periods in which its hash value remains unchanged. CIM objects are examples of unchanged-hashable objects in pywbem.
DeprecationWarning
a standard Python warning that indicates a deprecated functionality. See section Deprecation policy and the standard Python module warnings for details.
Element
class xml.dom.minidom.Element. Its methods are described in section Element Objects of module xml.dom, with minidom specifics described in section DOM Objects of module xml.dom.minidom.
CIM data type
one of the types listed in CIM data types.
CIM object
one of the types listed in CIM objects.
keybindings input object

a Python object used as input for initializing an ordered list of keybindings in a parent object (i.e. a CIMInstanceName object).

None will result in an an empty list of keybindings.

Otherwise, the type of the input object must be one of:

  • iterable of CIMProperty
  • iterable of tuple(key, value)
  • OrderedDict with key and value
  • dict with key and value (will not preserve order)

with the following definitions for key and value:

  • key (string): Keybinding name.

    Must not be None.

    The lexical case of the string is preserved. Object comparison and hash value calculation are performed case-insensitively.

  • value (CIM data type or number or CIMProperty): Keybinding value.

    If specified as CIM data type or number, the provided object will be stored unchanged as the keybinding value.

    If specified as a CIMProperty object, its name attribute must match the key (case insensitively), and a copy of its value (a CIM data type) will be stored as the keybinding value.

    None for the keybinding value will be stored unchanged.

The order of keybindings in the parent object is preserved if the input object is an iterable or a OrderedDict object, but not when it is a dict object.

The resulting set of keybindings in the parent object is independent of the input object (except for unmutable objects), so that subsequent modifications of the input object by the caller do not affect the parent object.

methods input object

a Python object used as input for initializing an ordered list of methods represented as CIMMethod objects in a parent object that is a CIMClass.

None will result in an an empty list of methods.

Otherwise, the type of the input object must be one of:

  • iterable of CIMMethod
  • iterable of tuple(key, value)
  • OrderedDict with key and value
  • dict with key and value (will not preserve order)

with the following definitions for key and value:

  • key (string): Method name.

    Must not be None.

    The lexical case of the string is preserved. Object comparison and hash value calculation are performed case-insensitively.

  • value (CIMMethod): Method declaration.

    Must not be None.

    The name attribute of the CIMMethod object must match the key (case insensitively).

    The provided object is stored in the parent object without making a copy of it.

The order of methods in the parent object is preserved if the input object is an iterable or a OrderedDict object, but not when it is a dict object.

The resulting set of methods in the parent object is independent of the input collection object, but consists of the same CIMMethod objects that were provided in the input collection. Therefore, a caller must be careful to not accidentally modify the provided CIMMethod objects.

parameters input object

a Python object used as input for initializing an ordered list of parameters represented as CIMParameter objects in a parent object that is a CIMMethod.

None will result in an an empty list of parameters.

Otherwise, the type of the input object must be one of:

  • iterable of CIMParameter
  • iterable of tuple(key, value)
  • OrderedDict with key and value
  • dict with key and value (will not preserve order)

with the following definitions for key and value:

  • key (string): Parameter name.

    Must not be None.

    The lexical case of the string is preserved. Object comparison and hash value calculation are performed case-insensitively.

  • value (CIMParameter): Parameter (declaration).

    Must not be None.

    The name attribute of the CIMParameter object must match the key (case insensitively).

    The provided object is stored in the parent object without making a copy of it.

The order of parameters in the parent object is preserved if the input object is an iterable or a OrderedDict object, but not when it is a dict object.

The resulting set of parameters in the parent object is independent of the input collection object, but consists of the same CIMParameter objects that were provided in the input collection. Therefore, a caller must be careful to not accidentally modify the provided CIMParameter objects.

properties input object

a Python object used as input for initializing an ordered list of properties represented as CIMProperty objects, in a parent object.

The CIMProperty objects represent property values when the parent object is a CIMInstance, and property declarations when the parent object is a CIMClass.

None will result in an an empty list of properties.

Otherwise, the type of the input object must be one of:

  • iterable of CIMProperty
  • iterable of tuple(key, value)
  • OrderedDict with key and value
  • dict with key and value (will not preserve order)

with the following definitions for key and value:

  • key (string): Property name.

    Must not be None.

    The lexical case of the string is preserved. Object comparison and hash value calculation are performed case-insensitively.

  • value (CIM data type or CIMProperty): Property (value or declaration).

    Must not be None.

    CIMProperty objects can be used as input for both property values and property declarations. CIM data type objects can only be used for property values.

    If specified as a CIM data type, a new CIMProperty object will be created from the provided value, inferring its CIM data type from the provided value.

    If specified as a CIMProperty object, its name attribute must match the key (case insensitively), and the provided object is stored in the parent object without making a copy of it.

The order of properties in the parent object is preserved if the input object is an iterable or a OrderedDict object, but not when it is a dict object.

The resulting set of properties in the parent object is independent of the input collection object, but consists of the same CIMProperty objects that were provided in the input collection. Therefore, a caller must be careful to not accidentally modify the provided CIMProperty objects.

qualifiers input object

a Python object used as input for initializing an ordered list of qualifiers represented as CIMQualifier objects in a parent object (e.g. in a CIMClass object).

None will result in an an empty list of qualifiers.

Otherwise, the type of the input object must be one of:

  • iterable of CIMQualifier
  • iterable of tuple(key, value)
  • OrderedDict with key and value
  • dict with key and value (will not preserve order)

with the following definitions for key and value:

  • key (string): Qualifier name.

    Must not be None.

    The lexical case of the string is preserved. Object comparison and hash value calculation are performed case-insensitively.

  • value (CIM data type or CIMQualifier): Qualifier (value).

    Must not be None.

    If specified as a CIM data type, a new CIMQualifier object will be created from the provided value, inferring its CIM data type from the provided value.

    If specified as a CIMQualifier object, its name attribute must match the key (case insensitively), and the provided object is stored in the parent object without making a copy of it.

The order of qualifiers in the parent object is preserved if the input object is an iterable or a OrderedDict object, but not when it is a dict object.

The resulting set of qualifiers in the parent object is independent of the input collection object, but consists of the same CIMQualifier objects that were provided in the input collection. Therefore, a caller must be careful to not accidentally modify the provided CIMQualifier objects.

11.2. Troubleshooting

Here are some trouble shooting hints for the installation of pywbem.

11.2.1. AttributeError for NullHandler during mkvirtualenv on Python 2.6

If the mkvirtualenv command fails on Python 2.6 with this error:

File "/usr/lib/python2.6/site-packages/stevedore/__init__.py", line 23,
  in <module> LOG.addHandler(logging.NullHandler())
AttributeError: 'module' object has no attribute 'NullHandler'

then the stevedore PyPI package is too recent(!) The owners of that package spent effort to remove the previously existing Python 2.6 support in some steps, starting with stevedore v1.10.

The solution is to use stevedore v1.9. Note that for virtualenvwrapper to use it, it must be installed into the system Python:

$ sudo pip install stevedore==1.9

11.2.2. TypeError about StreamHandler argument ‘stream’ during mkvirtualenv on Python 2.6

If the mkvirtualenv command fails on Python 2.6 with this error:

File "/usr/lib/python2.6/site-packages/virtualenvwrapper/hook_loader.py",
  line 101, in main
console = logging.StreamHandler(stream=sys.stderr)
TypeError: __init__() got an unexpected keyword argument 'stream'

then the virtualenvwrapper PyPI package is too old. As of its released version v4.7.1, a fix for that is in the master branch of its repository and has not been released yet.

While a new version of virtualenvwrapper with the fix is not yet released, a solution is to clone the virtualenvwrapper repository and to install it from its working directory. Note that it must be installed into the system Python:

$ git clone https://bitbucket.org/dhellmann/virtualenvwrapper.git virtualenvwrapper
$ cd virtualenvwrapper
$ sudo python setup.py install

11.2.3. Swig error ‘Unrecognized option -builtin’ during M2Crypto install

On Python 2.x, pywbem uses the M2Crypto package from PyPI and installs it during its own installation. The M2Crypto package invokes the Swig tool during its installation. If the version of Swig is too old, the invocation of Swig fails with:

swig error : Unrecognized option -builtin

The solution is to use Swig v2.0 or higher.

The pywbem setup script checks the version of Swig and installs a newer version of Swig, or if not available builds Swig from its sources (while automatically installing any further OS-level prerequisites needed for building Swig).

11.2.4. gcc does not find Python.h while installing M2Crypto

On Python 2.x, pywbem uses the M2Crypto package from PyPI and installs it during its own installation. The M2Crypto package invokes the Swig tool during its installation. Swig invokes the gcc compiler on source code it produces. That source code needs the Python.h header file.

If the invocation of gcc fails with:

SWIG/_m2crypto_wrap.c:127:20: fatal error: Python.h: No such file or directory

then you do not have the Python.h header file available.

The installation of pywbem with OS-level prereqs (see Installation) installs the necessary Python SDK package for C/C++ (or displays its package name). On RHEL, the missing package is python-dev. For more details, see Prerequisite operating system packages for development.

11.3. Glossary

dynamic indication filter
dynamic filter
An indication filter in a WBEM server whose life cycle is managed by a client. See DSP1054 for an authoritative definition and for details.
static indication filter
static filter
An indication filter in a WBEM server that pre-exists and whose life cycle cannot be managed by a client. See DSP1054 for an authoritative definition and for details.