Displaying Task Names and States (C++)

These two C++ examples show how to enumerate tasks. One example shows how to display information for tasks in a task folder, and the other examples shows how to display information for all running tasks.

The following procedure describes how to display task names and state for all the tasks in a task folder.

Aa446864.wedge(en-us,VS.85).gifTo display task names and state for all the tasks in a task folder

  1. Initialize COM and set general COM security.
  2. Create the ITaskService object.

    This object allows you to connect to the Task Scheduler service and access a specific task folder.

  3. Get a task folder that holds the tasks you want information about.

    Use the ITaskService::GetFolder method to get the folder.

  4. Get the collection of tasks from the folder.

    Use the ITaskFolder::GetTasks method to get the collection of tasks (IRegisteredTaskCollection).

  5. Get the number of tasks in the collection, and enumerate through each task in the collection.

    Use the Item Property of IRegisteredTaskCollection to get an IRegisteredTask instance. Each instance will contain a task in the collection. You can then display the information (property values) from each registered task.

The following C++ example shows how to display the name and state of all the tasks in the root task folder.


/********************************************************************
 This sample enumerates through the tasks on the local computer and 
 displays their name and state. 
********************************************************************/

#define _WIN32_DCOM

#include <windows.h>
#include <iostream>
#include <stdio.h>
#include <comdef.h>
//  Include the task header file.
#include <taskschd.h>
#pragma comment(lib, "taskschd.lib")
#pragma comment(lib, "comsupp.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 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 CoCreate an instance of the TaskService class: %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.
    ITaskFolder *pRootFolder = NULL;
    hr = pService->GetFolder( _bstr_t( L"\\") , &pRootFolder );
    
    pService->Release();
    if( FAILED(hr) )
    {
        printf("Cannot get Root Folder pointer: %x", hr );
        CoUninitialize();
        return 1;
    }
    
    //  -------------------------------------------------------
    //  Get the registered tasks in the folder.
    IRegisteredTaskCollection* pTaskCollection = NULL;
    hr = pRootFolder->GetTasks( NULL, &pTaskCollection );

    pRootFolder->Release();
    if( FAILED(hr) )
    {
        printf("Cannot get the registered tasks.: %x", hr);
        CoUninitialize();
        return 1;
    }

    LONG numTasks = 0;
    hr = pTaskCollection->get_Count(&numTasks);

    if( numTasks == 0 )
     {
        printf("\nNo Tasks are currently running" );
        pTaskCollection->Release();
        CoUninitialize();
        return 1;
     }

    printf("\nNumber of Tasks : %d", numTasks );

    TASK_STATE taskState;
    
    for(LONG i=0; i < numTasks; i++)
    {
        IRegisteredTask* pRegisteredTask = NULL;
        hr = pTaskCollection->get_Item( _variant_t(i+1), &pRegisteredTask );
        
        if( SUCCEEDED(hr) )
        {
            BSTR taskName = NULL;
            hr = pRegisteredTask->get_Name(&taskName);
            if( SUCCEEDED(hr) )
            {
                printf("\nTask Name: %S", taskName);
                SysFreeString(taskName);

                hr = pRegisteredTask->get_State(&taskState);
                if (SUCCEEDED (hr) )
                    printf("\n\tState: %d", taskState);
                else 
                    printf("\n\tCannot get the registered task state: %x", hr);
            }
            else
            {
                printf("\nCannot get the registered task name: %x", hr);
            }
            pRegisteredTask->Release();
        }
        else
        {
            printf("\nCannot get the registered task item at index=%d: %x", i+1, hr);
        }
    }

    pTaskCollection->Release();
    CoUninitialize();
    return 0;
}



The following procedure describes how to display task names and state for all running tasks.

Aa446864.wedge(en-us,VS.85).gifTo display task names and state for all running tasks

  1. Initialize COM and set general COM security.
  2. Create the ITaskService object.

    This object allows you to connect to the Task Scheduler service and access a specific task folder.

  3. Use the ITaskService::GetRunningTasks method to get a collection of all the running tasks (IRunningTaskCollection). You can specify to get instances of running task either including or excluding hidden tasks.
  4. Get the number of tasks in the collection, and enumerate through each task in the collection.

    Use the Item property of IRunningTaskCollection to get an IRunningTask instance. Each instance will contain a task in the collection. You can then display the information (property values) from each registered task.

The following C++ example shows how to display the name and state of all the running tasks, including hidden tasks.


/********************************************************************
 This sample enumerates through all running tasks on the local computer and 
 displays their name and state. 
********************************************************************/

#define _WIN32_DCOM

#include <windows.h>
#include <iostream>
#include <stdio.h>
#include <comdef.h>
//  Include the task header file.
#include <taskschd.h>
#pragma comment(lib, "taskschd.lib")
#pragma comment(lib, "comsupp.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 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 CoCreate an instance of the TaskService class: %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 running tasks.
	   IRunningTaskCollection* pRunningTasks = NULL;
	   hr = pService->GetRunningTasks(TASK_ENUM_HIDDEN, &pRunningTasks);

    pService->Release();
    if( FAILED(hr) )
    {
        printf("Cannot get Root Folder pointer: %x", hr );
        CoUninitialize();
        return 1;
    }
        
    LONG numTasks = 0;
    hr = pRunningTasks->get_Count(&numTasks);

    if( numTasks == 0 )
     {
        printf("\nNo Tasks are currently running" );
        pRunningTasks->Release();
        CoUninitialize();
        return 1;
     }

    printf("\nNumber of running tasks : %d", numTasks );

    TASK_STATE taskState;
    
    for(LONG i=0; i < numTasks; i++)
    {
        IRunningTask* pRunningTask = NULL;
        hr = pRunningTasks->get_Item( _variant_t(i+1), &pRunningTask );
        
        if( SUCCEEDED(hr) )
        {
            BSTR taskName = NULL;
            hr = pRunningTask->get_Name(&taskName);
            if( SUCCEEDED(hr) )
            {
                printf("\nTask Name: %S", taskName);
                SysFreeString(taskName);

                hr = pRunningTask->get_State(&taskState);
                if (SUCCEEDED (hr) )
                    printf("\n\tState: %d", taskState);
                else 
                    printf("\n\tCannot get the registered task state: %x", hr);
            }
            else
            {
                printf("\nCannot get the registered task name: %x", hr);
            }
            pRunningTask->Release();
        }
        else
        {
            printf("\nCannot get the registered task item at index=%d: %x", i+1, hr);
        }
    }

    pRunningTasks->Release();
    CoUninitialize();
    return 0;
}


Related topics

Using the Task Scheduler

 

 

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