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Using the Task Scheduler in Vista and Windows Server 2008

by Abel Avram on Feb 28, 2008 |

Task Scheduler is an useful addition to Windows Vista and the upcoming Windows Server 2008. This is a quick lesson on how to use the Task Scheduler from managed code. For a more detailed explanation, please visit the corresponding Bart De Smet's blog page.

Windows Vista and the upcoming Windows Server 2008 offer the possibility to create complex tasks which can be run at various moments in time. It would be great to have access to this functionality embedded into the OS from managed code. The first step is to create a C# Console Application, then import the taskschd.dll library found in the System32 folder. This will create the TaskScheduler COM interop assembly. Then create a TaskSchedulerClass like this:

TaskSchedulerClass scheduler = new TaskSchedulerClass();

 The next step is to connect to the scheduler:

TaskSchedulerClass scheduler = new TaskSchedulerClass();
scheduler.Connect(null, null, null, null);

The next step is to create a task, and choose one of the many settings it can have:

ITaskDefinition task = scheduler.NewTask(0);
task.RegistrationInfo.Author = "Author";
task.RegistrationInfo.Description = "New Task";
task.Settings.RunOnlyIfIdle = true;

Following is choosing a moment when the task should start. That is done by means of triggers. Our example will use a daily trigger as shown:

IDailyTrigger trigger = (IDailyTrigger)task.Triggers.Create(_TASK_TRIGGER_TYPE2.TASK_TRIGGER_DAILY);
trigger.Id = "DailyTrigger";
trigger.StartBoundary = "2008-01-01T12:00:00";
trigger.EndBoundary = "2008-01-31T12:00:00";

The task will run when the conditions set in the trigger are met. But an action has to be defined, otherwise the task will do nothing. This is an example:

IEmailAction action = (IEmailAction)task.Actions.Create(_TASK_ACTION_TYPE.TASK_ACTION_SEND_EMAIL);
action.Id = "Email action";
action.Server = "server...";
action.From = "sender...";
action.To = "recipient...";
action.Subject = "The subject of the email...";
action.Body = "The body text of the email...";

The task is almost ready to be used. It just needs to be registered.

ITaskFolder folder = scheduler.GetFolder("\\Task");
IRegisteredTask regTask = folder.RegisterTaskDefinition(
    "Test",
    task,
    (int)_TASK_CREATION.TASK_CREATE_OR_UPDATE,
    null, //user
    null, // password
    _TASK_LOGON_TYPE.TASK_LOGON_INTERACTIVE_TOKEN,
    "");

The task is completed and registered. It can be run now as shown below, or by using "schtasks /run".

IRunningTask runTask = regTask.Run(null);

Putting it all together results:

using System;
using System.Collections.Generic;
using System.Text;

namespace TaskScheduler {
    class Program {
        static void Main (string[] args) {
            TaskSchedulerClass scheduler = new TaskSchedulerClass();
            scheduler.Connect(null, null, null, null);

            ITaskDefinition task = scheduler.NewTask(0);
            task.RegistrationInfo.Author = "Author";
            task.RegistrationInfo.Description = "New Task";
            task.Settings.RunOnlyIfIdle = true;

            IDailyTrigger trigger = (IDailyTrigger)task.Triggers.Create(_TASK_TRIGGER_TYPE2.TASK_TRIGGER_DAILY);
            trigger.Id = "DailyTrigger";
            trigger.StartBoundary = "2008-01-01T12:00:00";
            trigger.EndBoundary = "2008-01-31T12:00:00";

            IEmailAction action = (IEmailAction)task.Actions.Create(_TASK_ACTION_TYPE.TASK_ACTION_SEND_EMAIL);
            action.Id = "Email action";
            action.Server = "server...";
            action.From = "sender...";
            action.To = "recipient...";
            action.Subject = "The subject of the email...";
            action.Body = "The body text of the email...";

            ITaskFolder folder = scheduler.GetFolder("\\Task");
            IRegisteredTask regTask = folder.RegisterTaskDefinition(
                "Test",
                task,
                (int)_TASK_CREATION.TASK_CREATE_OR_UPDATE,
                null, //user
                null, // password
                _TASK_LOGON_TYPE.TASK_LOGON_INTERACTIVE_TOKEN,
                "");

            IRunningTask runTask = regTask.Run(null);
        }
    }
}

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