|
version 1.5, 2004/10/13 14:45:26
|
version 1.6, 2005/03/01 06:18:02
|
|
|
|
| various classes. See http://www-124.ibm.com/developerworks/projects/sblim . | various classes. See http://www-124.ibm.com/developerworks/projects/sblim . |
| | |
| | |
| |
Using CQL with CMPI |
| |
------------------- |
| |
|
| |
To use CQL support for indications and exec query you will have to use |
| |
the Pegasus/Provider/CMPI/cmpi_cql.h header file with one new function. |
| |
You also you need to define PEGASUS_USE_EXPERIMENTAL in your |
| |
code to take advantage of these CQL utility functions. The reason is that |
| |
the CMPI standard 1.0 is unclear on one thing: |
| |
|
| |
- CMNewSelectExp. One of arguments passed is a 'projection' array. The |
| |
spec does not explain exactly what in such array. Implementation of |
| |
CMPI that also implemented WQL put a string representation of the |
| |
properties, as "SystemName", "Hostname", etc. But that is not neccesarily |
| |
the case with CQL, where you can have chained identifiers such as |
| |
"CIM_OperatingSystem::SystemName". In other words, the CMPI standard |
| |
needs to clarify this and to make the existing providers backward |
| |
supported, this utility function - CMPI_CQL_NewSelectExp is provided |
| |
until the CMPI standard comes up with a conclusion on this. |
| |
|
| |
When the CMPI provides a resolution on these issues, this utility |
| |
interface will be gone and unsupported. |
| |
|
| |
Questions and Answers: |
| |
Q1: Is the CMPI Specification really ambiguous or does it |
| |
just not support CQL? If it's ambiguous should it be fixed |
| |
before it goes final? |
| |
|
| |
A1:. Page 96 of the CMPI review spec states (line 2899-2901): The *projection output argument is |
| |
a pointer to a CMPIArray structure of CMPIString entries containing projection specification. |
| |
It shall be set to NULL if no projection is defined.. To clarify any ambigiuity, an e-mail to the |
| |
CMPI review group was sent, which would add the following: The projection specification is query |
| |
language specific. Hence the entries format of the projection output array CMPIString might be |
| |
different depending on the query language. Be sure to check the lang argument for the query language your |
| |
provider will support. . To guard the provider from DMTF's CQL possible ways it can be represented in |
| |
a string format, and since the CQL is experimental, the CMNewSelectExp will NOT support CQL. |
| |
The CMPI_CQL_NewSelect will support both CQL and WQL. |
| |
|
| |
|
| |
AQ:What happens if an existing Provider is passed a CQL |
| |
statement and issues a newSelectExp call? Does it return |
| |
an error? |
| |
|
| |
A2: The error code CMPI_RC_ERR_QUERY_LANGUAGE_NOT_SUPPORTED would be set. |
| |
|
| |
|
| |
Q3: Both CMNewSelectExp and CMPI_CQL_NewSelectExp return a |
| |
CMPISelectExp. Is there anyway to determine whether the |
| |
CMPISelectExp represents a CQL or WQL expression? |
| |
|
| |
A3:Not from the scope of the CMPISelectExp structure. Please note that the routine |
| |
that would exercise the CMPISelectExp has a char *lang passed in as argument. |
| |
This char *lang* can be used to easily determine what query language is used. |
| |
|
| |
|
| |
|
| Registering CMPI providers with Pegasus | Registering CMPI providers with Pegasus |
| --------------------------------------- | --------------------------------------- |
| | |
Return to
readme.cmpi
CVS log
Up to [Pegasus] / pegasus