include functionality that will reduce the need for vendor extensions
by working with the major vendors to standardize their extensions.
While this helps to achieve the goal of having a standard that
enables interoperability, it also adds to the complexity of the specifi-
cation and the ability of vendors to fully implement it.
Common Warehouse Metadata for Data Mining
Common Warehouse Metadata (CWM) for data mining provides a
metamodel for representing data mining metadata in XML. It is
based on the more general CWM specification [CWM 2005].
The Common Warehouse Metamodel (CWM™) is a specification that describes
metadata interchange among data warehousing, business intelligence, knowledge
management and portal technologies. The OMG Meta-Object Facility (MOF™)
bridges the gap between dissimilar meta-models by providing a common basis for
meta-models. If two different meta-models are both MOF-conformant, then models
based on them can reside in the same repository. [CWM 2005]
In particular, CWM uses XML Metadata Interchange (XMI) to
interchange data warehouse metadata, which is based on the more
general CWM metamodel. The CWM metamodel is specified using
the MOF model, allowing XMI to be used to (1) transform the CWM
metamodel into a CWM document type definition (DTD), (2) transfer
instances of warehouse metadata that conform to the CWM meta-
model as XML documents, based on the CWM DTD, and (3) trans-
form the CWM metamodel itself into an XML document, based on
the MOF DTD for interchange between MOF-compliant repositories.
These specifications work together to allow warehouse metadata
and the CWM metamodel to be interchanged using W3C's Extensi-
ble Markup Language (XML). CWM allows Interface Definition
Language (IDL) to be used for specifying programmatic access to
data warehouse metadata—based on the CWM metamodel. Other
programming language APIs may be generated based on the CWM
IDL and specific IDL programming language mappings (e.g., IDL-
Java and CORBA-COM). The CWM DTD, CWM XML, and CWM
IDL specifications are automatically generated from the CWM meta-
model, as defined by the MOF and XMI specifications. (See Chapter
15 of [OMG 2001] for a detailed description of the data mining
portion of the standard.)
OMG's charter is to produce and maintain specifications for
interoperable enterprise applications in the computer industry.
OMG membership includes nearly all large computer industry