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Registration Trigger Example (C++)

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This C++ example shows how to create a task that is scheduled to execute Notepad when a task is registered. The task contains a registration trigger that specifies a start boundary and an end boundary for the task and also a delay for the task. The start boundary specifies when the trigger is activated, and the delay sets the amount of time between when the task is registered and when the task is started. The task also contains an action that specifies the task to execute Notepad.

Note

When a task with a registration trigger is updated, the task will execute after the update occurs.

 

The following procedure describes how to schedule a task to start an executable when the task is registered.

To schedule Notepad to start when a task is registered

  1. Initialize COM and set general COM security.
  2. Create the ITaskService object. This object allows you to create tasks in a specified folder.
  3. Get a task folder to create a task in. Use the ITaskService::GetFolder method to get the folder, and the ITaskService::NewTask method to create the ITaskDefinition object.
  4. Define information about the task using the ITaskDefinition object, such as the registration information for the task. Use the RegistrationInfo property of ITaskDefinition and other properties of the ITaskDefinition interface to define the task information.
  5. Create a registration trigger using the Triggers property of ITaskDefinition to access the ITriggerCollection for the task. Use the ITriggerCollection::Create method (specifying the type of trigger you want to create) to create a registration trigger.
  6. Create an action for the task to execute by using the Actions property of ITaskDefinition to access the IActionCollection interface for the task. Use the IActionCollection::Create method to specify the type of action that you want to create. This example uses an IExecAction object, which represents an action that executes a command-line operation.
  7. Register the task using the ITaskFolder::RegisterTaskDefinition method.

The following C++ example shows how to schedule a task to execute Notepad 30 seconds after the task is registered.

C++ 
/********************************************************************
 This sample schedules a task to start notepad.exe 30 seconds after
 the task is registered. 
********************************************************************/

#define _WIN32_DCOM

#include <windows.h>
#include <iostream>
#include <stdio.h>
#include <comdef.h>
#include <wincred.h>
//  Include the task header file.
#include <taskschd.h>
#pragma comment(lib, "taskschd.lib")
#pragma comment(lib, "comsupp.lib")
#pragma comment(lib, "credui.lib")

using namespace std;


int __cdecl wmain()
{
    //  ------------------------------------------------------
    //  Initialize COM.
    HRESULT hr = CoInitializeEx(NULL, COINIT_MULTITHREADED);
    if( FAILED(hr) )
    {
        printf("\nCoInitializeEx failed: %x", hr );
        return 1;
    }

    //  Set general COM security levels.
    hr = CoInitializeSecurity(
        NULL,
        -1,
        NULL,
        NULL,
        RPC_C_AUTHN_LEVEL_PKT_PRIVACY,
        RPC_C_IMP_LEVEL_IMPERSONATE,
        NULL,
        0,
        NULL);

    if( FAILED(hr) )
    {
        printf("\nCoInitializeSecurity failed: %x", hr );
        CoUninitialize();
        return 1;
    }

    //  ------------------------------------------------------
    //  Create a name for the task.
    LPCWSTR wszTaskName = L"Registration Trigger Test Task";

    //  Get the windows directory and set the path to notepad.exe.
    wstring wstrExecutablePath = _wgetenv( L"WINDIR");
    wstrExecutablePath += L"\\SYSTEM32\\NOTEPAD.EXE";


    //  ------------------------------------------------------
    //  Create an instance of the Task Service. 
    ITaskService *pService = NULL;
    hr = CoCreateInstance( CLSID_TaskScheduler,
                           NULL,
                           CLSCTX_INPROC_SERVER,
                           IID_ITaskService,
                           (void**)&pService );  
    if (FAILED(hr))
    {
        printf("Failed to create an instance of ITaskService: %x", hr);
        CoUninitialize();
        return 1;
    }
        
    //  Connect to the task service.
    hr = pService->Connect(_variant_t(), _variant_t(),
        _variant_t(), _variant_t());
    if( FAILED(hr) )
    {
        printf("ITaskService::Connect failed: %x", hr );
        pService->Release();
        CoUninitialize();
        return 1;
    }

    //  ------------------------------------------------------
    //  Get the pointer to the root task folder.  This folder will hold the
    //  new task that is registered.
    ITaskFolder *pRootFolder = NULL;
    hr = pService->GetFolder( _bstr_t( L"\\") , &pRootFolder );
    if( FAILED(hr) )
    {
        printf("Cannot get Root Folder pointer: %x", hr );
        pService->Release();
        CoUninitialize();
        return 1;
    }
    
    //  If the same task exists, remove it.
    hr = pRootFolder->DeleteTask( _bstr_t( wszTaskName), 0  );
    
    //  Create the task builder object to create the task.
    ITaskDefinition *pTask = NULL;
    hr = pService->NewTask( 0, &pTask );

    pService->Release();  // COM clean up.  Pointer is no longer used.
    if (FAILED(hr))
    {
        printf("Failed to create a task definition: %x", hr);
        pRootFolder->Release();
        CoUninitialize();
        return 1;
    }
        
    //  ------------------------------------------------------
    //  Get the registration info for setting the identification.
    IRegistrationInfo *pRegInfo= NULL;
    hr = pTask->get_RegistrationInfo( &pRegInfo );
    if( FAILED(hr) )
    {
        printf("\nCannot get identification pointer: %x", hr );
        pRootFolder->Release();
        pTask->Release();
        CoUninitialize();
        return 1;
    }
    
    hr = pRegInfo->put_Author( L"Author Name" );
    pRegInfo->Release(); 
    if( FAILED(hr) )
    {
        printf("\nCannot put identification info: %x", hr );
        pRootFolder->Release();
        pTask->Release();
        CoUninitialize();
        return 1;
    }

    //  ------------------------------------------------------
    //  Create the principal for the task
    IPrincipal *pPrincipal = NULL;
    hr = pTask->get_Principal( &pPrincipal );
    if( FAILED(hr) )
    {
        printf("\nCannot get principal pointer: %x", hr );
        pRootFolder->Release();
        pTask->Release();
        CoUninitialize();
        return 1;
    }
    
    //  Set up principal information: 
    hr = pPrincipal->put_Id( _bstr_t(L"Principal1") ); 
    if( FAILED(hr) )
        printf("\nCannot put the principal ID: %x", hr);

    hr = pPrincipal->put_LogonType( TASK_LOGON_INTERACTIVE_TOKEN );
    if( FAILED(hr) )
        printf("\nCannot put principal logon type: %x", hr);

    //  Run the task with the least privileges (LUA) 
    hr = pPrincipal->put_RunLevel( TASK_RUNLEVEL_LUA ); 
    pPrincipal->Release();  
    if( FAILED(hr) )
    {
        printf("\nCannot put principal run level: %x", hr );
        pRootFolder->Release();
        pTask->Release();
        CoUninitialize();
        return 1;
    }
   

    //  ------------------------------------------------------
    //  Create the settings for the task
    ITaskSettings *pSettings = NULL;
    hr = pTask->get_Settings( &pSettings );
    if( FAILED(hr) )
    {
        printf("\nCannot get settings pointer: %x", hr );
        pRootFolder->Release();
        pTask->Release();
        CoUninitialize();
        return 1;
    }
    
    //  Set setting values for the task.
    hr = pSettings->put_StartWhenAvailable(VARIANT_TRUE);    
    pSettings->Release(); 
    if( FAILED(hr) )
    {
        printf("\nCannot put setting info: %x", hr );
        pRootFolder->Release();
        pTask->Release();
        CoUninitialize();
        return 1;
    }

    //  ------------------------------------------------------
    //  Get the trigger collection to insert the registration trigger.
    ITriggerCollection *pTriggerCollection = NULL;
    hr = pTask->get_Triggers( &pTriggerCollection );
    if( FAILED(hr) )
    {
        printf("\nCannot get trigger collection: %x", hr );
        pRootFolder->Release();
        pTask->Release();
        CoUninitialize();
        return 1;
    }

    //  Add the registration trigger to the task.
    ITrigger *pTrigger = NULL;    
    hr = pTriggerCollection->Create( TASK_TRIGGER_REGISTRATION, &pTrigger );
    pTriggerCollection->Release();
    if( FAILED(hr) )
    {
        printf("\nCannot create a registration trigger: %x", hr );
        pRootFolder->Release();
        pTask->Release();
        CoUninitialize();
        return 1;
    }     
    
    IRegistrationTrigger *pRegistrationTrigger = NULL;
    hr = pTrigger->QueryInterface( 
        IID_IRegistrationTrigger, (void**) &pRegistrationTrigger );
    pTrigger->Release();
    if( FAILED(hr) )
    {
        printf("\nQueryInterface call failed on IRegistrationTrigger: %x", hr );
        pRootFolder->Release();
        pTask->Release();
        CoUninitialize();
        return 1;
    }
    
    hr = pRegistrationTrigger->put_Id( _bstr_t( L"Trigger1" ) );
    if( FAILED(hr) )
        printf("\nCannot put trigger ID: %x", hr);
    
    //  Define the delay for the registration trigger.
    hr = pRegistrationTrigger->put_Delay( L"PT30S" );
    pRegistrationTrigger->Release();
    if( FAILED(hr) )
    {
        printf("\nCannot put registration trigger delay: %x", hr );
        pRootFolder->Release();
        pTask->Release();
        CoUninitialize();
        return 1;
    }   
    

    //  ------------------------------------------------------
    //  Add an Action to the task. This task will execute notepad.exe.     
    IActionCollection *pActionCollection = NULL;

    //  Get the task action collection pointer.
    hr = pTask->get_Actions( &pActionCollection );
    if( FAILED(hr) )
    {
        printf("\nCannot get Task collection pointer: %x", hr );
        pRootFolder->Release();
        pTask->Release();
        CoUninitialize();
        return 1;
    }
    
    //  Create the action, specifying that it is an executable action.
    IAction *pAction = NULL;
    hr = pActionCollection->Create( TASK_ACTION_EXEC, &pAction );
    pActionCollection->Release();
    if( FAILED(hr) )
    {
        printf("\nCannot create action: %x", hr );
        pRootFolder->Release();
        pTask->Release();
        CoUninitialize();
        return 1;
    }

    IExecAction *pExecAction = NULL;

    //  QI for the executable task pointer.
    hr = pAction->QueryInterface( 
        IID_IExecAction, (void**) &pExecAction );
    pAction->Release();
    if( FAILED(hr) )
    {
        printf("\nQueryInterface call failed for IExecAction: %x", hr );
        pRootFolder->Release();
        pTask->Release();
        CoUninitialize();
        return 1;
    }

    //  Set the path of the executable to notepad.exe.
    hr = pExecAction->put_Path( _bstr_t( wstrExecutablePath.c_str() ) ); 
    pExecAction->Release(); 
    if( FAILED(hr) )
    {
        printf("\nCannot put the action executable path: %x", hr );
        pRootFolder->Release();
        pTask->Release();
        CoUninitialize();
        return 1;
    }

    
    //  ------------------------------------------------------
    //  Save the task in the root folder.
    IRegisteredTask *pRegisteredTask = NULL;
    hr = pRootFolder->RegisterTaskDefinition(
            _bstr_t( wszTaskName ),
            pTask,
            TASK_CREATE_OR_UPDATE, 
            _variant_t(), 
            _variant_t(), 
            TASK_LOGON_INTERACTIVE_TOKEN,
            _variant_t(L""),
            &pRegisteredTask);
    if( FAILED(hr) )
    {
        printf("\nError saving the Task : %x", hr );
        pRootFolder->Release();
        pTask->Release();
        CoUninitialize();
        return 1;
    }
    
    printf("\n Success! Task successfully registered. " );

    //  Clean up.
    pRootFolder->Release();
    pTask->Release();
    pRegisteredTask->Release();
    CoUninitialize();
    return 0;
}

Using the Task Scheduler