Multiple instances of the same service in Delphi

Question

I have have an old windows service made in delphi that now has to be installed multiple times in the same server, I am trying to change the code so I am able to change the service name as I am instaling the service but I cannot make it work.

I find some information here and some here about it, and after study the posts and make the necessary modifications I am able to install two services with different names, however the services does not start.

I post the class responsible to control the service below (inherited TService), I know is quite a bit of code but I would really appreciate any help.

procedure ServiceController(CtrlCode: DWord); stdcall;
begin
  tvdAvalancheDataCenterService.Controller(CtrlCode);
end;
function TtvdAvalancheDataCenterService.GetServiceController: TServiceController;
begin
  Result := ServiceController;
end;
procedure TtvdAvalancheDataCenterService.ServiceLoadInfo(Sender : TObject);
begin
  Name := ParamStr(2);
  DisplayName := ParamStr(3);
end;
procedure TtvdAvalancheDataCenterService.ServiceBeforeInstall(Sender: TService);
begin
  ServiceLoadInfo(Self);
end;
procedure TtvdAvalancheDataCenterService.ServiceCreate(Sender: TObject);
begin
  ServiceLoadInfo(Self);
end;
procedure TtvdAvalancheDataCenterService.ServiceStart(Sender: TService;
  var Started: Boolean);
begin
  FtvdTrayIcon := TtvdEnvoyTrayIcon.Create(Self);
  SetServiceDescription;
  FtvdDataCenter.tvdActive := true;
end;
procedure TtvdAvalancheDataCenterService.ServiceStop(Sender: TService;
  var Stopped: Boolean);
begin
  FreeAndNil(FtvdTrayIcon);
  FtvdDataCenter.tvdActive := False;
end;
procedure TtvdAvalancheDataCenterService.ServiceAfterInstall(Sender: TService);
begin
   SetServiceDescription;
end;
procedure TtvdAvalancheDataCenterService.SetServiceDescription;
var
  aReg: TRegistry;
begin
  if FDescriptionUpdated then
    Exit;
  aReg := TRegistry.Create(KEY_READ or KEY_WRITE);
  try
    aReg.RootKey := HKEY_LOCAL_MACHINE;
    if aReg.OpenKey(cnRegKey+ Name, true) then
    begin
      aReg.WriteString('Description', cnServiceDescription);
      aReg.CloseKey;
    end;
    FDescriptionUpdated:= True;
  finally
    aReg.Free;
  end;
end;

I am using Delphi XE and the service need to run in windows services.

Thanks in advance

Answer 1

Since the service does not know what name it has received on installation, you can supply that name as a parameter into it's ImagePath registry value.

here's a basic service skeleton for multiple instances:

unit u_svc_main;

interface

uses
  Winapi.Windows,
  System.Win.Registry,
  System.SysUtils,
  System.Classes,
  Vcl.Dialogs,
  Vcl.SvcMgr;

type
  TSvc_test = class(TService)
    procedure ServiceAfterInstall(Sender: TService);
    procedure ServiceBeforeInstall(Sender: TService);
    procedure ServiceCreate(Sender: TObject);
    procedure ServiceBeforeUninstall(Sender: TService);
  private
    { Private declarations }
    procedure GetServiceName;
    procedure GetServiceDisplayName;
  public
    function GetServiceController: TServiceController; override;
    { Public declarations }
  end;

var
  Svc_test: TSvc_test;

implementation

{$R *.dfm}
procedure TSvc_test.GetServiceDisplayName;

var
  ServiceDisplayName : String;

begin
 if not FindCmdLineSwitch('display', ServiceDisplayName) then
  raise Exception.Create('Please specify the service displayname with /display switch');
 DisplayName := ServiceDisplayName;
end;

procedure TSvc_test.GetServiceName;

var
  ServiceName : String;

begin
 if not FindCmdLineSwitch('name', ServiceName) then
  raise Exception.Create('Please specify the service name with /name switch');
 Name := ServiceName;
end;

procedure ServiceController(CtrlCode: DWord); stdcall;
begin
  Svc_test.Controller(CtrlCode);
end;

function TSvc_test.GetServiceController: TServiceController;
begin
  Result := ServiceController;
end;

procedure TSvc_test.ServiceAfterInstall(Sender: TService);

var
  Reg       : TRegistry;
  ImagePath : String;

begin
 Reg := TRegistry.Create(KEY_READ OR KEY_WRITE);
 try
  Reg.RootKey := HKEY_LOCAL_MACHINE;
  if Reg.OpenKey('SYSTEM\CurrentControlSet\Services\'+Name, False) then
   begin
    // set service description
    Reg.WriteString('Description', 'Multi instance test for service '+Name);
    // add name parameter to ImagePath value
    ImagePath := ParamStr(0) + ' /name '+Name;
    Reg.WriteString('ImagePath', ImagePath);
    Reg.CloseKey;
   end;
 finally
  Reg.Free;
 end;
end;

procedure TSvc_test.ServiceBeforeInstall(Sender: TService);
begin
 GetServiceName;
 GetServiceDisplayName;
end;

procedure TSvc_test.ServiceBeforeUninstall(Sender: TService);
begin
 GetServiceName;
end;

procedure TSvc_test.ServiceCreate(Sender: TObject);
begin
 if not Application.Installing then
  GetServiceName;
end;

end.

Service installation:

<path1>\MyService.Exe /install /name "test1" /display "test instance1"
<path2>\MyService.Exe /install /name "test2" /display "test instance2"

Service removal:

<path1>\MyService.Exe /uninstall /name "test1" 
<path2>\MyService.Exe /uninstall /name "test2" 

Answer 2

It's fairly simple. You just have to set the name different for each service.

You now have:

Name := ParamStr(2);

DisplayName := ParamStr(3);

and just have to change it to:

Name := baseServiceName + '-' + GetLastDirName;

DisplayName := baseServiceDisplayName + ' (' + GetLastDirName + ')';

where baseServiceName is a constant with the name of the service; baseServiceDisplayName is a constant with the display name and GetLastDirName is a function that returns the name of a directory (last directory) from ExtractFilePath(ParamStr(0))

```

function GetLastDirName: string;
var
  aux: string;
  p: Integer;
begin
  aux := strDelSlash(ExtractFilePath(ParamStr(0)));
  p := StrLastPos('\', aux);
  if p > 0 then
    result := Copy(aux, p + 1, Length(aux))
  else
    result := aux;
end;

```

strDelSlash deletes the last slash; StrLastPos searches for the last position of the slash

Answer 3

The solution suggested by @whosrdaddy works for me.

However the eventviewer displays logged messages (MyService.LogMessage(...)) as undefined or uninstalled.

These messages displays fine if the name and the displayname are same as were at designtime. There are few predefined message types, linked in exetubale, as resources.

With Eventwiver the user can attach any user defined action, when any of predefined events occur.