WMI SDK Sample - WMIDiskPerf

Windows Management Instrumentation SDK Sample

WMIDiskPerf

The WMIDiskPerf sample surfaces disk performance information produced by the DiskPerf driver using WMI. The driver produces disk partition performance instrumentation data and exposes this data through a WMI interface. The information provided includes statistics such as number of bytes read and written, number of read and write operations performed and the time these operations took to complete. The DiskPerf driver is included as a sample on the Windows 2000 Professional DDK and is also standard as part of the Windows 2000 Professional operating system installation.

Building the WMIDiskPerf Sample

The application can be built from the command line using NMAKE, or it can be built using Microsoft Visual C++.

From the command line in the sample installation directory, type the following:

NMAKE /f "Makefile"

From Microsoft Visual C++:

1. Select File + Open Workspace

2. Select the WMIDiskPerf.dsp file

Getting Started with the WMIDiskPerf Sample

To use this sample, the following steps are required:

1) Install Windows 2000 Professional operating system.

2) Install the WMI SDK for Windows 2000.

3) Build the sample application provided here, using the WMI SDK to produce WMIDiskPerf.exe.

4) If desired, the DiskPerf driver in the Windows 2000 Professional DDK can replace the one from the operating system install. To do so, compile the DiskPerf driver in the DDK and substitute it for the standard driver.

5) Execute the WMIDiskPerf sample. You should see instrumentation data produced by the DiskPerf driver visible via the WMI application. From the command line in the sample installation directory, type the following:

WMIDiskPerf.exe

General Notes

Things to remember when you're building your own WMI client application:

1. If you want your client to run on NT and non-DCOM versions of Windows 95, manually load the ole32.dll and see if CoInitializeSecurity() exists. This routine won’t exist on Windows 95 installations that don’t have DCOM installed separately. If this routine doesn't exist, the asynchronous routines in this sample won’t work because of mismatched security level problems. The synchronous techniques will still work.

2. If you don’t care about non-DCOM versions of Windows 95, you can define _WIN32_DCOM so that CoInitializeSecurity() is available for implicit linking. Don't use _WIN32_WINNT to get this prototype since it won't compile under the Windows 95/98 operating systems.

3. In any case, the CoInitializeSecurity() call (in InitInstance()) is required to work around a security problem when WMI trying to call a Sink object but won't identify itself. The CoInitializeSecurity() call turns off the authentication requirement.

4. WMI interfaces are defined in wbemcli.h and wbemprov.h found in the wmi\include directory. You may #include both these files by including just wbemidl.h located in the same directory.

5. WMI interface CLSIDs are defined in wbemuuid.lib. If you get unresolved externals in interfaces and CLSIDs, this is what is missing.

6. You'll need to link with oleaut32.lib and ole32.lib to get the needed COM support.

7. In the Link|Output settings, specify 'wWinMainCRTStartup' as the entry point. This is per the Unicode programming instructions.

8. If you're using the makefiles, don't forget to set the Visual C++ environment variables. This is done by running VCVARS32.BAT.