CIM to ODBC Mapping

[This is preliminary documentation and subject to change.]

The Common Information Model (CIM) maps to ODBC as follows:

CIM namespaces map to ODBC databases.

In CIM, namespaces are instances of the __NameSpace class. Namespaces can contain child namespaces, which can be enumerated like any other instance of a class.

CIM classes map to ODBC tables.

The table qualifier is the fully qualified __NameSpace name. A class is unique. If a class exists in two different namespaces, the adapter maps them as two different tables.

CIM class properties map to table columns as follows:

The property name becomes the column name.
The property value becomes the column value.
The property qualifiers become column metadata.

The property qualifiers are exposed to the ODBC clients by using SQLColumns. Some of the metadata is used to determine the standard metadata exposed by SQLColumns. All qualifiers are contained as a SQL_LONGVARCHAR in a thirteenth column added to the resultant rowset. The adapter only exposes qualifiers on a per-class basis, not on a per-class, per-instance basis. Therefore, information in qualifiers that vary over instances is inaccessible. See SQLColumns for more information.

CIM class qualifiers map to metadata of a table (as exposed through SQLTables).

A sixth column of the rowset has been added to SQLTables to return all class qualifiers as an SQL_LONGVARCHAR. For more information, see SQLTables. The adapter exposes qualifiers on a per-class basis only. Therefore, the adapter does not access qualifier information that varies across instances.

CIM data types map to ODBC SQL data types.

CIM uses variants to return property values. The ODBC adapter supports these variant types. The CIMTYPE attribute has more semantics than the variant type. For example, if the variant type is BSTR and the CIMTYPE is IpAddress, the variant BSTR is in fact an IP address. The adapter uses the CIMTYPE attribute sparingly. For more information on data types, see Appendix D of the ODBC 2.0 Programmer's Reference and SDK Guide.

The following table shows the mapping of variant types to ODBC types.

Variant Type	Data source-Dependent Name	CIMTYPE String	SQL Type

VT_UI1	UINT8	UINT8	SQL_TINYINT
VT_I2	SINT8	SINT8	SQL_TINYINT
VT_I2	SINT16	SINT16 Default case if nothing else matches	SQL_SMALLINT
VT_I4	UINT16	UINT16	SQL_SMALLINT
VT_I4	UINT32	UINT32	SQL_INTEGER
VT_I4	SINT32	SINT32 Default case if nothing else matches	SQL_INTEGER
VT_BSTR	SINT64	SINT64	SQL_BIGINT
VT_BSTR	UINT64	UINT64	SQL_BIGINT
VT_BSTR	INTERVAL	INTERVAL	SQL_TIMESTAMP
VT_BSTR	TIMESTAMP	DATETIME	SQL_TIMESTAMP
VT_BSTR	DATE	DATE	SQL_DATE
VT_BSTR	TIME	TIME	SQL_TIME
VT_BSTR	SMALL_STRING	STRING The property must also have a MAX qualifier with a value <= 254. Default case if nothing else matches If the MAX qualifier value cannot be retrieved, the default value of 254 is used.	SQL_VARCHAR
VT_BSTR	STRING	STRING The property must also have a MAX qualifier with value > 254. If MAX qualifier value > 16384, it is truncated to 16384.	SQL_LONGVARCHAR
VT_R4	REAL		SQL_DOUBLE
VT_R8	DOUBLE		SQL_DOUBLE
VT_BOOL	BIT		SQL_BIT
VT_ARRAY \| VT_UI1	SINT8_ARRAY	SINT8	SQL_LONGVARBINARY
VT_ARRAY \| VT_I2	UINT8_ARRAY	UINT8	SQL_LONGVARBINARY
VT_ARRAY \| VT_I2	SINT16_ARRAY	SINT16 Default case if nothing else matches	SQL_LONGVARBINARY
VT_ARRAY \| VT_I4	UINT16_ARRAY	UINT16	SQL_LONGVARBINARY
VT_ARRAY \| VT_I4	UINT32_ARRAY	UINT32	SQL_LONGVARBINARY
VT_ARRAY \| VT_I4	SINT32_ARRAY	SINT32 Default case if nothing else matches	SQL_LONGVARBINARY
VT_ARRAY \| VT_BOOL	BOOL_ARRAY		SQL_LONGVARBINARY
VT_ARRAY \| VT_R4	REAL_ARRAY		SQL_LONGVARBINARY
VT_ARRAY \| VT_R8	DOUBLE_ARRAY		SQL_LONGVARBINARY
VT_ARRAY \| VT_BSTR	SINT64_ARRAY	SINT64	SQL_LONGVARBINARY
VT_ARRAY \| VT_BSTR	UINT64_ARRAY	UINT64	SQL_LONGVARBINARY
VT_ARRAY \| VT_BSTR	STRING_ARRAY	STRING Default case if nothing else matches	SQL_LONGVARBINARY
VT_ARRAY \| VT_BSTR	INTERVAL_ARRAY	INTERVAL	SQL_LONGVARBINARY
VT_ARRAY \| VT_BSTR	TIMESTAMP_ARRAY	DATETIME	SQL_LONGVARBINARY
VT_ARRAY \| VT_BSTR	DATE_ARRAY	DATE	SQL_LONGVARBINARY
VT_ARRAY \| VT_BSTR	TIME_ARRAY	TIME	SQL_LONGVARBINARY

As the table shows, CIM supports multiple array types. These array types are returned as binary data. However, through ODBC, these array values can also be returned as ASCII strings. For example:

An integer array is [-3] [200] [50] [45].
A floating point array is [1.234567] [234.567890].
A string array is [billy] [jack] [freddy].

Use SQLColumns to get the data source-dependent type in order to distinguish between [-3][200][50][45] as an array of integers and an array of strings (which just look like numbers).

If an array name or value contains a left or right square bracket within itself, the brackets are doubled in the ASCII representation. For example, fr[ed]dy is shown as:

[fr[[ed]]dy]

CIM class and property qualifiers that change with the instance of a class are not exposed.

CIM associations are only exposed insofar as they are represented by classes. Thus, foreign keys are not used in a table to relate the classes of an association.

An ODBC data source can include several databases. See Connecting to a Data Source for information on database configuration.