Passing OLE DB Conformance Tests
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To make providers more consistent, the Data Access SDK provides a set of OLE DB conformance tests. The tests check all aspects of your provider and give you reasonable assurance that your provider functions as expected. You can find the OLE DB conformance tests on the Microsoft Data Access SDK. This section focuses on things you should do to pass the conformance tests. For information about running the OLE DB conformance tests, see the SDK.
Running the Conformance Tests
In Visual C++ 6.0, the OLE DB provider templates added a number of hooking functions to allow you to check values and properties. Most of these functions were added in response to the conformance tests.
Note
You need to add several validation functions for your provider to pass the OLE DB conformance tests.
This provider requires two validation routines. The first routine, CRowsetImpl::ValidateCommandID, is part of your rowset class. It is called during the creation of the rowset by the provider templates. The sample uses this routine to tell consumers that it does not support indexes. The first call is to CRowsetImpl::ValidateCommandID (note that the provider uses the _RowsetBaseClass typedef added in the interface map for CMyProviderRowset in Provider Support for Bookmarks, so you do not have to type that long line of template arguments). Next, return DB_E_NOINDEX if the index parameter is not NULL (this indicates the consumer wants to use an index on us). For more information about command IDs, see the OLE DB specification and look for IOpenRowset::OpenRowset.
The following code is the ValidateCommandID validation routine:
/////////////////////////////////////////////////////////////////////
// MyProviderRS.H
// Class: CMyProviderRowset
HRESULT ValidateCommandID(DBID* pTableID, DBID* pIndexID)
{
HRESULT hr = _RowsetBaseClass::ValidateCommandID(pTableID, pIndexID);
if (hr != S_OK)
return hr;
if (pIndexID != NULL)
return DB_E_NOINDEX; // Doesn't support indexes
return S_OK;
}
The provider templates call the OnPropertyChanged method whenever someone changes a property on the DBPROPSET_ROWSET group. If you want to handle properties for other groups, you add them to the appropriate object (that is, DBPROPSET_SESSION checks go in the CMyProviderSession class).
The code first checks to see whether the property is linked to another. If the property is being chained, it sets the DBPROP_BOOKMARKS property to True. Appendix C of the OLE DB specification contains information about properties. This information also tells you whether the property is chained to another one.
You might also want to add the IsValidValue routine to your code. The templates call IsValidValue when attempting to set a property. You would override this method if you require additional processing when setting a property value. You can have one of these methods for each property set.
Threading Issues
By default, the OLE DB Provider Wizard in the ATL OLE DB Provider Wizard generates code for the provider to run in an apartment model. If you attempt to run this code with the conformance tests, you initially get failures. This is because Ltm.exe, the tool used to run the OLE DB conformance tests, defaults to free threaded. The OLE DB Provider Wizard code defaults to apartment model for performance and ease of use.
To correct this problem, you can either change LTM or change the provider.
To change LTM to run in apartment threaded mode
On the LTM main menu, click Tools, and then click Options.
On the General tab, change the threading model from Free Threaded to Apartment Threaded.
To change your provider to run in free threaded mode:
In your provider project, search for all instances of
CComSingleThreadModeland replace it withCComMultiThreadModel, which should be in your data source, session, and rowset headers.In your .rgs file, change the threading model from Apartment to Both.
Follow correct programming rules for free threaded programming (that is, lock on writes).