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Writing Your Own Customized Handler

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You may want to write your own handler if you are an IIS server administrator who wants the default RDS support, but more control over user requests and access rights.

The MSDFMAP.Handler implements the IDataFactoryHandler interface.

Important

Beginning with Windows 8 and Windows Server 2012, RDS server components are no longer included in the Windows operating system (see Windows 8 and Windows Server 2012 Compatibility Cookbook for more detail). RDS client components will be removed in a future version of Windows. Avoid using this feature in new development work, and plan to modify applications that currently use this feature. Applications that use RDS should migrate to WCF Data Service.

IDataFactoryHandler Interface

This interface has two methods, GetRecordset and Reconnect. Both methods require that the CursorLocation property be set to adUseClient.

Both methods take arguments that appear after the first comma in the "Handler=" keyword. For example, "Handler=progid,arg1,arg2;" will pass an argument string of "arg1,arg2", and "Handler=progid" will pass a null argument.

GetRecordset Method

This method queries the data source and creates a new Recordset object using the arguments provided. The Recordset must be opened with adLockBatchOptimistic and must not be opened asynchronously.

Arguments

conn The connection string.

args The arguments for the handler.

query The command text for making a query.

ppRS The pointer where the Recordset should be returned.

Reconnect Method

This method updates the data source. It creates a new Connection object and attaches the given Recordset.

Arguments

conn The connection string.

args The arguments for the handler.

pRS A Recordset object.

msdfhdl.idl

This is the interface definition for IDataFactoryHandler that appears in the msdfhdl.idl file.

[  
  uuid(D80DE8B3-0001-11d1-91E6-00C04FBBBFB3),  
  version(1.0)  
]  
library MSDFHDL  
{  
    importlib("stdole32.tlb");  
    importlib("stdole2.tlb");  
  
    // TLib : Microsoft ActiveX Data Objects 2.0 Library  
    // {00000200-0000-0010-8000-00AA006D2EA4}  
    #ifdef IMPLIB  
    importlib("implib\\x86\\release\\ado\\msado15.dll");  
    #else  
    importlib("msado20.dll");  
    #endif  
  
    [  
      odl,  
      uuid(D80DE8B5-0001-11d1-91E6-00C04FBBBFB3),  
      version(1.0)  
    ]  
    interface IDataFactoryHandler : IUnknown  
    {  
HRESULT _stdcall GetRecordset(  
      [in] BSTR conn,  
      [in] BSTR args,  
      [in] BSTR query,  
      [out, retval] _Recordset **ppRS);  
  
// DataFactory will use the ActiveConnection property  
// on the Recordset after calling Reconnect.  
   HRESULT _stdcall Reconnect(  
      [in] BSTR conn,  
      [in] BSTR args,  
      [in] _Recordset *pRS);  
    };  
};

See Also

Customization File Connect Section
Customization File Logs Section
Customization File SQL Section
Customization File UserList Section
DataFactory Customization
Required Client Settings
Understanding the Customization File