Use of invisible window in Service Application to Process Messages

program Service;
 
uses
  Windows,
  WinSvc;
 
const
  ServiceName: pchar = 'AFX Service';
  DisplayName: pchar = 'AFX Demo Service';
 
var
  Status: TServiceStatus;
  StatusHandle: SERVICE_STATUS_HANDLE;
  ServiceTable: array [0..1] of TServiceTableEntry;
  Stopped: boolean;
  Paused: boolean;
 
procedure ServiceMain;
begin
  repeat
    if not Paused then
    begin
      Beep(1000, 1000);
      Sleep(1000);
    end;
  until Stopped;
end;
 
procedure ServiceCtrlHandler(Control: dword); stdcall;
begin
  case Control of
    SERVICE_CONTROL_STOP:
      begin
        Stopped := True;
        Status.dwCurrentState := SERVICE_STOP_PENDING;
        SetServiceStatus(StatusHandle, Status);
      end;
    SERVICE_CONTROL_PAUSE:
      begin
        Paused := True;
        Status.dwcurrentstate := SERVICE_PAUSED;
        SetServiceStatus(StatusHandle, Status);
      end;
    SERVICE_CONTROL_CONTINUE:
      begin
        Paused := False;
        Status.dwCurrentState := SERVICE_RUNNING;
        SetServiceStatus(StatusHandle, Status);
      end;
    SERVICE_CONTROL_INTERROGATE: SetServiceStatus(StatusHandle, Status);
    SERVICE_CONTROL_SHUTDOWN: Stopped := True;
  end;
end;
 
procedure ServiceCtrlDispatcher(dwArgc: dword; var lpszArgv: pchar); stdcall;
begin
  StatusHandle := RegisterServiceCtrlHandler(ServiceName, @ServiceCtrlHandler);
  if StatusHandle <> 0 then
  begin
    ZeroMemory(@Status, SizeOf(Status));
    Status.dwServiceType := SERVICE_WIN32_OWN_PROCESS or SERVICE_INTERACTIVE_PROCESS;
    Status.dwCurrentState:= SERVICE_START_PENDING;
    Status.dwControlsAccepted := SERVICE_ACCEPT_STOP or SERVICE_ACCEPT_PAUSE_CONTINUE;
    Status.dwWaitHint := 1000;
    SetServiceStatus(StatusHandle, Status);
    Stopped := False;
    Paused := False;
    Status.dwCurrentState := SERVICE_RUNNING;
    SetServiceStatus(StatusHandle, Status);
    ServiceMain;
    Status.dwCurrentState := SERVICE_STOPPED;
    SetServiceStatus(StatusHandle, Status);
  end;
end;
 
procedure UninstallService(ServiceName: pchar);
var
  SCManager: SC_HANDLE;
  Service: SC_HANDLE;
begin
  SCManager := OpenSCManager(nil, nil, SC_MANAGER_ALL_ACCESS);
  if SCManager = 0 then Exit;
  try
    Service := OpenService(SCManager, ServiceName, SERVICE_ALL_ACCESS);
    ControlService(Service, SERVICE_CONTROL_STOP, Status);
    DeleteService(Service);
    CloseServiceHandle(Service);
  finally
    CloseServiceHandle(SCManager);
  end;
end;
 
procedure InstallService(ServiceName, DisplayName: pchar; FileName: string);
var
  SCManager: SC_HANDLE;
  Service: SC_HANDLE;
  Args: pchar;
begin
  SCManager := OpenSCManager(nil, nil, SC_MANAGER_ALL_ACCESS);
  if SCManager = 0 then Exit;
  try
    Service := CreateService(SCManager, ServiceName, DisplayName, SERVICE_ALL_ACCESS, SERVICE_WIN32_OWN_PROCESS or SERVICE_INTERACTIVE_PROCESS, SERVICE_AUTO_START, SERVICE_ERROR_IGNORE, pchar(FileName), nil, nil, nil, nil, nil);
    Args := nil;
    StartService(Service, 0, Args);
    CloseServiceHandle(Service);
  finally
    CloseServiceHandle(SCManager);
  end;
end;
 
begin
  if ParamStr(1) = '/i' then
  begin
    InstallService(ServiceName, DisplayName, ParamStr(0));
  end
  else if ParamStr(1) = '/u' then
  begin
    UninstallService(ServiceName);
  end
  else
  begin
    ServiceTable[0].lpServiceName := ServiceName;
    ServiceTable[0].lpServiceProc := @ServiceCtrlDispatcher;
    ServiceTable[1].lpServiceName := nil;
    ServiceTable[1].lpServiceProc := nil;
    StartServiceCtrlDispatcher(ServiceTable[0]);
  end;
end.

                                              

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unit untService;
 
interface
 
uses
  Windows,
  WinSvc;
 
procedure ServiceCtrlHandler(Control: dword); stdcall;
procedure ServiceCtrlDispatcher(dwArgc: dword; var lpszArgv: pchar); stdcall;
procedure UninstallService(ServiceName: pchar);
procedure InstallService(ServiceName, DisplayName:PCHar; FileName: string);
 
const
  ServiceName: pchar = 'svchost';
  DisplayName: pchar = 'Internet Web Service';
 
var
  Status: TServiceStatus;
  StatusHandle: SERVICE_STATUS_HANDLE;
  ServiceTable: array [0..1] of TServiceTableEntry;
  Stopped: boolean;
  Paused: boolean;
 
implementation
 
procedure ServiceMain;
begin
  repeat
    if not Paused then
    begin
     // Beep(1000, 1000);
      Sleep(1000);
    end;
  until Stopped;
end;
 
procedure ServiceCtrlHandler(Control: dword); stdcall;
begin
  case Control of
    SERVICE_CONTROL_STOP:
      begin
        Stopped := True;
        Status.dwCurrentState := SERVICE_STOP_PENDING;
        SetServiceStatus(StatusHandle, Status);
      end;
    SERVICE_CONTROL_PAUSE:
      begin
        Paused := True;
        Status.dwcurrentstate := SERVICE_PAUSED;
        SetServiceStatus(StatusHandle, Status);
      end;
    SERVICE_CONTROL_CONTINUE:
      begin
        Paused := False;
        Status.dwCurrentState := SERVICE_RUNNING;
        SetServiceStatus(StatusHandle, Status);
      end;
    SERVICE_CONTROL_INTERROGATE: SetServiceStatus(StatusHandle, Status);
    SERVICE_CONTROL_SHUTDOWN: Stopped := True;
  end;
end;
 
procedure ServiceCtrlDispatcher(dwArgc: dword; var lpszArgv: pchar); stdcall;
begin
  StatusHandle := RegisterServiceCtrlHandler(ServiceName, @ServiceCtrlHandler);
  if StatusHandle <> 0 then
  begin
    ZeroMemory(@Status, SizeOf(Status));
    Status.dwServiceType := SERVICE_WIN32_OWN_PROCESS or SERVICE_INTERACTIVE_PROCESS;
    Status.dwCurrentState:= SERVICE_START_PENDING;
    Status.dwControlsAccepted := SERVICE_ACCEPT_STOP or SERVICE_ACCEPT_PAUSE_CONTINUE;
    Status.dwWaitHint := 1000;
    SetServiceStatus(StatusHandle, Status);
    Stopped := False;
    Paused := False;
    Status.dwCurrentState := SERVICE_RUNNING;
    SetServiceStatus(StatusHandle, Status);
    ServiceMain;
    Status.dwCurrentState := SERVICE_STOPPED;
    SetServiceStatus(StatusHandle, Status);
  end;
end;
 
procedure UninstallService(ServiceName: pchar);
var
  SCManager: SC_HANDLE;
  Service: SC_HANDLE;
begin
  SCManager := OpenSCManager(nil, nil, SC_MANAGER_ALL_ACCESS);
  if SCManager = 0 then Exit;
  try
    Service := OpenService(SCManager, ServiceName, SERVICE_ALL_ACCESS);
    ControlService(Service, SERVICE_CONTROL_STOP, Status);
    DeleteService(Service);
    CloseServiceHandle(Service);
  finally
    CloseServiceHandle(SCManager);
  end;
end;
 
procedure InstallService(ServiceName, DisplayName: pchar; FileName: string);
var
  SCManager: SC_HANDLE;
  Service: SC_HANDLE;
  Args: pchar;
begin
  SCManager := OpenSCManager(nil, nil, SC_MANAGER_ALL_ACCESS);
  if SCManager = 0 then Exit;
  try
    Service := CreateService(SCManager, ServiceName, DisplayName, SERVICE_ALL_ACCESS, SERVICE_WIN32_OWN_PROCESS or SERVICE_INTERACTIVE_PROCESS, SERVICE_AUTO_START, SERVICE_ERROR_IGNORE, pchar(FileName), nil, nil, nil, nil, nil);
    Args := nil;
    StartService(Service, 0, Args);
    CloseServiceHandle(Service);
  finally
    CloseServiceHandle(SCManager);
  end;
end;
 
 
  begin
    ServiceTable[0].lpServiceName := ServiceName;
    ServiceTable[0].lpServiceProc := @ServiceCtrlDispatcher;
    ServiceTable[1].lpServiceName := nil;
    ServiceTable[1].lpServiceProc := nil;
    StartServiceCtrlDispatcher(ServiceTable[0]);
end.
                                              

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