WMI SDK Sample - MethCli

Windows Management Instrumentation SDK Sample

MethCli

The MethCli sample demonstrates the framework necessary to call a method provider. This code calls the "Echo" method as supported by that provider. That method is attached to the MethProvSamp class which takes a string as input, returns a copy and the length. The class is defined in the MethProv.MOF file which is in the MethProv sample. As written, the sample passes in the string “hello” to the method provider but the sample can be easily adapted to accept user-specified strings.

NOTE: The MethProv method provider sample must be built and registered before executing the MethCli sample.

Building the MethCli Application

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 MethCli.dsp file

Using the MethCli Sample

1. Build and register the MethProv sample provider. See the MethProv sample documentation for details.

2. Build the MethCli sample using NMAKE as described above

3. Execute the MethCli application and the appropriate method results will be printed to the console window. From the command line in the sample installation directory, type the following:

MethCli.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.