TWmiMethod Component For Delphi, C++Builder

TWmiMethod is a part of WmiSet Component Collection for Delphi, C++Builder. It executes the methods of WMI objects. This component cooperates with TWmiQuery and TWmiConnection to retrieve the objects whose methods are to be called. The component provides the following capabilities:

Retrieves a WMI object from TWmiQuery or TWmiConnection;
Retrieves a list of methods supported by the WMI object;
Automatically detects the input parameters of the method;
Allows to access parameters by name (use ParamByName method);
Automatically detects and requests the privileges required to execute the method;
Executes static and dynamic methods of objects;
Automatically creates the output parameters that keep the results of method execution;
Analyzes the output parameters and retrieves the error code and description.
Retrieves the WMI method qualifiers that report the various information about the object's method: description, required privileges, possible return value etc.

Code Example: TWmiMethod and TWmiQuery

This 40-line long program is a Delphi 6 example that shows how to use TWmiMethod and TWmiQuery to start the service. It properly handles the errors. The name of the service to start should be the first command line parameter.

program StartService;

{$APPTYPE CONSOLE}
uses
  Variants, SysUtils, WmiDataSet, 
  WmiConnection, WmiMethod;

var
  vQuery: TWmiQuery;
  vConnection: TWmiConnection;
  vMethod: TWmiMethod;
  i: integer;
  vName: string;
begin
  if ParamCount > 0 then vName := ParamStr(1) else Exit;

  vQuery := TWmiQuery.Create(nil);
  vConnection := TWmiConnection.Create(nil);
  vMethod := TWmiMethod.Create(nil);
  try
    vQuery.Connection := vConnection;
    vMethod.WmiObjectSource := vQuery;
    vQuery.WQL.Text := 'select * from Win32_Service';
    vQuery.Open;
    if vQuery.Locate('Name', vName, []) then
    begin
      vMethod.WmiMethodName := 'StartService';
      if vMethod.Execute = 0 then writeln('Ok')
        else writeln(vMethod.LastWmiErrorDescription);
    end else writeln('Service '+ vName + ' not found.');
  finally
    vMethod.Free;
    vQuery.Free;
    vConnection.Free;
  end;
end.

Code Example: Using ParamByName.

This piece of Delphi code shows how to assign the input parameters for a static WMI method call. This example schedules a task for execution. It assumes that TWmiConnection and TWmiMethod components are dropped on the form at design time, properly linked and connected to the destination computer.

procedure TForm1.CreateJob(Command: string; 
                              StartTime: TDateTime);
begin
  WmiConnection1.ObjectPath := 'Win32_ScheduledJob';
  with WmiMethod1 do
  begin
    WmiMethodName := 'Create';
    with InParams do
    begin
      ParamByName('Command').AsString := Command;
      ParamByName('StartTime').AsTime := StartTime;
      ParamByName('RunRepeatedly').AsBoolean := true;
      ParamByName('InteractWithDesktop').AsBoolean := true;
    end;
    if Execute <> 0 then
      raise Exception.Create(LastWmiErrorDescription);
  end;
end;

More examples.

WmiSet component collection comes with a number of examples that are using TWmiMethod component. Look in the examples\WmiMethods directory. Click on the image do download the demo application that can start, stop, pause, resume services on a local or remote computer.

The example project below changes the IP protocol settings on the local or network computers. It can set the IP address to be static, or enable DHCP. The Delphi source code is included. C++Builder version is also available. Click on the image to start download.