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WMI Tasks using Delphi – Services

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How do I determine which services are running and which ones are not?

Use the Win32_Service class to check the state of all of the services. The state property lets you know if a service is stopped or running.

const
  wbemFlagForwardOnly = $00000020;
var
  FSWbemLocator : OLEVariant;
  FWMIService   : OLEVariant;
  FWbemObjectSet: OLEVariant;
  FWbemObject   : OLEVariant;
  oEnum         : IEnumvariant;
  iValue        : LongWord;
begin;
  FSWbemLocator := CreateOleObject('WbemScripting.SWbemLocator');
  FWMIService   := FSWbemLocator.ConnectServer('localhost', 'root\CIMV2', '', '');
  FWbemObjectSet:= FWMIService.ExecQuery('SELECT Name, State FROM Win32_Service','WQL',wbemFlagForwardOnly);
  oEnum         := IUnknown(FWbemObjectSet._NewEnum) as IEnumVariant;
  while oEnum.Next(1, FWbemObject, iValue) = 0 do
  begin
    Writeln(Format('Name     %s',[String(FWbemObject.Name)]));// String
    Writeln(Format('State    %s',[String(FWbemObject.State)]));// String
    Writeln;
    FWbemObject:=Unassigned;
  end;
end;

How do I stop Power Users from starting certain services?

Use the Win32_Service class and the ChangeStartMode method to set the StartMode property to Disabled. Disabled services cannot be started, and, by default, Power Users cannot change the start mode of a service.

const
  wbemFlagForwardOnly = $00000020;
var
  FSWbemLocator : OLEVariant;
  FWMIService   : OLEVariant;
  FWbemObjectSet: OLEVariant;
  FWbemObject   : OLEVariant;
  oEnum         : IEnumvariant;
  iValue        : LongWord;
begin;
  FSWbemLocator := CreateOleObject('WbemScripting.SWbemLocator');
  FWMIService   := FSWbemLocator.ConnectServer('localhost', 'root\CIMV2', '', '');
  FWbemObjectSet:= FWMIService.ExecQuery('SELECT * FROM Win32_Service where StartMode = "Manual"','WQL',wbemFlagForwardOnly);
  oEnum         := IUnknown(FWbemObjectSet._NewEnum) as IEnumVariant;
  while oEnum.Next(1, FWbemObject, iValue) = 0 do
  begin
    FWbemObject.Change( varEmpty, varEmpty, varEmpty, varEmpty, 'Disabled');
    FWbemObject:=Unassigned;
  end;
end;

How do I start and stop services?

Use the Win32_Service class and the StopService and StartService methods.

const
  wbemFlagForwardOnly = $00000020;
var
  FSWbemLocator : OLEVariant;
  FWMIService   : OLEVariant;
  FWbemObjectSet: OLEVariant;
  FWbemObject   : OLEVariant;
  oEnum         : IEnumvariant;
  iValue        : LongWord;
begin;
  FSWbemLocator := CreateOleObject('WbemScripting.SWbemLocator');
  FWMIService   := FSWbemLocator.ConnectServer('localhost', 'root\CIMV2', '', '');
  FWbemObjectSet:= FWMIService.ExecQuery('SELECT * FROM Win32_Service where Name  = "Alerter"','WQL',wbemFlagForwardOnly);
  oEnum         := IUnknown(FWbemObjectSet._NewEnum) as IEnumVariant;
  if oEnum.Next(1, FWbemObject, iValue) = 0 then
    FWbemObject.StartService();
end;

How do I change service account passwords?

Use the Win32_Service class and the Change method.

const
  wbemFlagForwardOnly = $00000020;
var
  FSWbemLocator : OLEVariant;
  FWMIService   : OLEVariant;
  FWbemObjectSet: OLEVariant;
  FWbemObject   : OLEVariant;
  oEnum         : IEnumvariant;
  iValue        : LongWord;
begin;
  FSWbemLocator := CreateOleObject('WbemScripting.SWbemLocator');
  FWMIService   := FSWbemLocator.ConnectServer('localhost', 'root\CIMV2', '', '');
  FWbemObjectSet:= FWMIService.ExecQuery('SELECT * FROM Win32_Service where StartName = ".\netsvc"','WQL',wbemFlagForwardOnly);
  oEnum         := IUnknown(FWbemObjectSet._NewEnum) as IEnumVariant;
  if oEnum.Next(1, FWbemObject, iValue) = 0 then
    FWbemObject.Change( varEmpty, varEmpty, varEmpty, varEmpty, varEmpty, varEmpty, varEmpty, 'password');
end;

How do I determine which services I can stop?

Use the Win32_Service class, and check the value of the AcceptStop property.

const
  wbemFlagForwardOnly = $00000020;
var
  FSWbemLocator : OLEVariant;
  FWMIService   : OLEVariant;
  FWbemObjectSet: OLEVariant;
  FWbemObject   : OLEVariant;
  oEnum         : IEnumvariant;
  iValue        : LongWord;
begin;
  FSWbemLocator := CreateOleObject('WbemScripting.SWbemLocator');
  FWMIService   := FSWbemLocator.ConnectServer('localhost', 'root\CIMV2', '', '');
  FWbemObjectSet:= FWMIService.ExecQuery('SELECT * FROM Win32_Service where AcceptStop = True','WQL',wbemFlagForwardOnly);
  oEnum         := IUnknown(FWbemObjectSet._NewEnum) as IEnumVariant;
  while oEnum.Next(1, FWbemObject, iValue) = 0 do
  begin
    Writeln(Format('Name     %s',[String(FWbemObject.Name)]));// String
    FWbemObject:=Unassigned;
  end;
end;

How do I find the services that must be running before I can start the DHCP service?

Query for ASSOCIATORS OF the Win32_Service class named “DHCP” that are in the Win32_DependentService class and have “Dependent” in the Role property. Role means the role of the rasman service: in this case, it is antecedent to—must be started before—the dependent services.

const
  wbemFlagForwardOnly = $00000020;
var
  FSWbemLocator : OLEVariant;
  FWMIService   : OLEVariant;
  FWbemObjectSet: OLEVariant;
  FWbemObject   : OLEVariant;
  oEnum         : IEnumvariant;
  iValue        : LongWord;
begin;
  FSWbemLocator := CreateOleObject('WbemScripting.SWbemLocator');
  FWMIService   := FSWbemLocator.ConnectServer('localhost', 'root\CIMV2', '', '');
  FWbemObjectSet:= FWMIService.ExecQuery('Associators Of {Win32_Service.Name="dhcp"} Where AssocClass=Win32_DependentService Role=Dependent','WQL',wbemFlagForwardOnly);
  oEnum         := IUnknown(FWbemObjectSet._NewEnum) as IEnumVariant;
  while oEnum.Next(1, FWbemObject, iValue) = 0 do
  begin
    Writeln(Format('%s  - %s',[String(FWbemObject.Name),String(FWbemObject.DisplayName)]));// String
    FWbemObject:=Unassigned;
  end;
end;

How do I find the services that require the WMI service (Winmgmt) service to be running before they can start?

Query for ASSOCIATORS OF the Win32_Service class named “winmgmt” that are in the Win32_DependentService class and have “Antecendent” in the Role property. Role means the role of the rasman service: in this case, it is antecedent to—must be started before—the dependent services.

const
  wbemFlagForwardOnly = $00000020;
var
  FSWbemLocator : OLEVariant;
  FWMIService   : OLEVariant;
  FWbemObjectSet: OLEVariant;
  FWbemObject   : OLEVariant;
  oEnum         : IEnumvariant;
  iValue        : LongWord;
begin;
  FSWbemLocator := CreateOleObject('WbemScripting.SWbemLocator');
  FWMIService   := FSWbemLocator.ConnectServer('localhost', 'root\CIMV2', '', '');
  FWbemObjectSet:= FWMIService.ExecQuery('Associators of {Win32_Service.Name="winmgmt"} Where AssocClass=Win32_DependentService Role=Antecedent','WQL',wbemFlagForwardOnly);
  oEnum         := IUnknown(FWbemObjectSet._NewEnum) as IEnumVariant;
  while oEnum.Next(1, FWbemObject, iValue) = 0 do
  begin
    Writeln(Format('%s  - %s',[String(FWbemObject.Name),String(FWbemObject.DisplayName)]));// String
    FWbemObject:=Unassigned;
  end;
end;

This post is based in the MSDN Entry WMI Tasks: Services

Author: Rodrigo

Just another Delphi guy.

5 thoughts on “WMI Tasks using Delphi – Services”

Leave a comment

  1. Heinz Z
    November 17, 2011 at 4:51 am

    Thanks for your work.

    Currently I use nothing of this information at all but it gives me good feeling to know what I can do with Delphi and WMI and to know the place where I can find all of this informations.

    Reply
  2. Scott Pritchard
    January 1, 2012 at 6:30 pm

    Great Blog Rodrigo!

    Just wondering if you’d be able to do a writeup or post on how to seperate multiple values from a WMI query into seperate strings.

    For example, in a system with more than 1 RAM Module installed (root\cimv2\PhysicalMemory), being able to read the “Capacity” values, and seperate each return value/result into seperate strings (one string for each result). There’s a great many uses i can think of for this especially regarding hardware information (Multiple Video Card, Multi CPU/Multicore, Multiple Drives, etc).

    I apologise that this isn’t directly related to this post, but i wanted to contact you via twitter (unfortunately, the character limit can be a hassle at times).

    Keep up the good work either way!

    Reply
  3. Scott Pritchard
    January 2, 2012 at 1:16 pm

    Hi. I did try both those tools, and both are great but i don’t see a way to achieve what i’m trying to do.

    If i use the following code for example, in a system with 3 graphics cards, i get 3 values returned (in this case, 3 message boxes from ShowMessage). What i want to do is be able to do is put each value to a seperate string;

    var
    Locator: ISWbemLocator;
    Services: ISWbemServices;
    ObjSet: ISWbemObjectSet;
    SObject: ISWbemObject;
    PropSet: ISWbemPropertySet;
    SProp1 : ISWbemProperty;
    sValue1 : String;
    Enum: IEnumVariant;
    Value: Cardinal;
    TempObj: OleVariant;
    TmpInt : Integer;
    begin
    Locator:= CoSWbemLocator.Create;
    Services:= Locator.ConnectServer(‘.’, ‘root\cimv2’, ”, ”, ”,”, 0, nil);
    ObjSet:= Services.InstancesOf(‘Win32_VideoController’, wbemFlagReturnWhenComplete, nil);
    Enum:= (ObjSet._NewEnum) as IEnumVariant;
    while (Enum.Next(1, tempObj, Value) = S_OK) do begin
    SObject:= IUnknown(tempObj) as SWBemObject;
    PropSet := SObject.Properties_;

    SProp1:= PropSet.Item(‘AdapterRAM’,0);
    sValue1:= SProp1.Get_Value;
    TmpInt := StrToInt(sValue1);
    ShowMessage(IntToStr(TmpInt div 1048576) + ‘ Mb VRAM’);
    end;
    end;

    Reply
    • Rodrigo
      January 2, 2012 at 10:59 pm

      Scott, your question is more related to delphi collections than to the WMI, you can use a TList or even a StringList to store the values returned by you WQL sentence and then use as you want.

      Reply

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