Windows task scheduler api

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Windows Task Scheduler

Task Scheduler (formerly Scheduled Tasks)^[1] is a job scheduler in Microsoft Windows that launches computer programs or scripts at pre-defined times or after specified time intervals.^[2][3] Microsoft introduced this component in the Microsoft Plus! for Windows 95 as System Agent.^[4] Its core component is an eponymous Windows service.^[5] The Windows Task Scheduler infrastructure is the basis for the Windows PowerShell scheduled jobs feature introduced with PowerShell v3.^[6]

Task Scheduler can be compared to cron or anacron on Unix-like operating systems. This service should not be confused with the scheduler, which is a core component of the OS kernel that allocates CPU resources to processes already running.

Task Scheduler 1.0 is included with Windows NT 4.0^[7] (with Internet Explorer 4.0 or later), Windows 2000,^[7] Windows XP^[8] and Windows Server 2003.^[9] It runs as a Windows Service, and the task definitions and schedules are stored in binary .job files. Tasks are manipulated directly by manipulating the .job files. Each task corresponds to single action. On Windows 95 (with Internet Explorer 4.0 or later), Windows 98 and Windows Me, the Task Scheduler runs as an ordinary program, mstask.exe. It also displays a status icon in the notification area on Windows 95 and Windows 98 and runs as a hidden service on Windows Me, but can be made to show a tray icon.^[1] Computer programs and scripts can access the service through six COM interfaces.^[10] Microsoft provides a scheduling agent DLL, a sample VBScript and a configuration file to automate Task Scheduler.^[11]

In addition to the graphical user interface for Task Scheduler in Control Panel, Windows provides two command-line tools for managing scheduled task: at.exe (deprecated)^[12] and schtasks.exe.^[5][13][14] However, at.exe cannot access tasks created or modified by Control Panel or schtasks.exe.^[15] Also, tasks created with at.exe are not interactive by default; interactivity needs to be explicitly requested. The binary «.job» files which the AT command produces are stored in the %WINDIR%\Tasks directory.^[16][17]

Task Scheduler 2.0 was introduced with Windows Vista^[18] and included in Windows Server 2008 as well.^[19][9] The redesigned Task Scheduler user interface is now based on Management Console. In addition to running tasks on scheduled times or specified intervals, Task Scheduler 2.0 also supports calendar and event-based triggers, such as starting a task when a particular event is logged to the event log, or when a combination of events has occurred. Also, several tasks that are triggered by the same event can be configured to run either simultaneously or in a pre-determined chained sequence of a series of actions, instead of having to create multiple scheduled tasks. Tasks can also be configured to run based on system status such as being idle for a pre-configured amount of time, on startup,^[20] logoff, or only during or for a specified time. XPath expressions can be used to filter events from the Windows Event Log. Tasks can also be delayed for a specified time after the triggering event has occurred, or repeat until some other event occurs. Actions that need to be done if a task fails can also be configured. The actions that can be taken in response to triggers, both event-based as well as time-based, not only include launching applications but also take a number of custom actions. Task Scheduler includes a number of actions built-in, spanning a number of applications; including send an e-mail, show a message box, or fire a COM handler when it is triggered. Custom actions can also be specified using the Task Scheduler API. Task Scheduler keeps a history log of all execution details of all the tasks.^[21] Windows Vista uses Task Scheduler 2.0 to run various system-level tasks;^[22] consequently, the Task Scheduler service can no longer be disabled (except with a simple registry tweak).

Task Scheduler 2.0 exposes an API to allow computer programs and scripts create tasks.^[19][23] It consists of 42 COM interfaces.^[24] The Windows API does not, however, include a managed wrapper for Task Scheduler though an open source implementation exists.^[25] The job files for Task Scheduler 2.0 are XML-based, and are human-readable, conforming to the Task Scheduler Schema.^[19][23]

• New security features, including using Credential Manager to passwords for tasks on workgroup computers and using Active Directory for task credentials on domain-joined computers so that they cannot be retrieved easily. Also, scheduled tasks are executed in their own session, instead of the same session as system services or the current user.
• Ability to wake up a machine remotely or using BIOS timer from sleep or hibernation to execute a scheduled task or run a previously scheduled task after a machine gets turned on.
• Ability to attach tasks to events directly from the Event Viewer.

The Task Scheduler service works by managing Tasks; Task refers to the action (or actions) taken in response to trigger(s). A task is defined by associating a set of actions, which can include launching an application or taking some custom-defined action, to a set of triggers, which can either be time-based or event-based. In addition, a task also can contain metadata that defines how the actions will be executed, such as the security context the task will run in. Tasks are serialized to .job files and are stored in the special folder titled Task Folder, organized in subdirectories. Programmatically, the task folder is accessed using the ITaskFolder interface or the TaskFolder scripting object and individual tasks using the IRegisteredTask interface or RegisteredTask object.^[26]

The Last Result column displays a completion code. The common codes for scheduled tasks are:^[27][28]

On Windows 2000 and Windows XP, when a computer is prepared for disk imaging with the sysprep utility, it cannot run tasks configured to run in the context of the SYSTEM account. Sysprep changes the security identifier (SID) to avoid duplication but does not update scheduled tasks to use the new SID. Consequently, the affected tasks fail to run. There is no solution for this problem but one may reschedule the affected tasks to work around the issue.^[29]

On Windows Vista or Windows Server 2008, the next execution time displayed in Task Scheduler may be wrong. Microsoft issued a hotfix to remedy this issue.^[30]

• cron, job scheduler for Unix-like operating systems

• Leonhard, Woody; Rusen, Ciprian (2021). Windows 10 All-in-One For Dummies. John Wiley & Sons. ISBN 978-1119680574.
• Knittel, Brian; McFedries, Paul (2014). Windows 8.1 in Depth. Que Publishing. ISBN 978-0789752819.
• Bott, Ed; Siechert, Carl; Stinson, Craig (2009). Windows 7 Inside Out. Pearson Education. ISBN 978-0735636842.
• Ruest, Danielle; Ruest, Nelson (2008). Microsoft Windows Server 2008: The Complete Reference. McGraw-Hill Education. ISBN 978-0071596466.
• Cowart, Robert; Knittel, Brian (2008). Special Edition Using Microsoft Windows Vista. Que. ISBN 978-0789737816.

• Task Scheduler on MSDN
• The Log File in the Task Scheduler May Be Incorrectly Formatted and Difficult to Read — Archived October 16, 2007, at the Wayback Machine
• Unable to Delete Text in the Task Scheduler Log File
• Task Scheduler Service Does Not Start
• Scheduled Program Does Not Start in Task Scheduler — Archived August 21, 2006, at the Wayback Machine
• Cannot Disable Task Scheduler

Are you tired of manually performing repetitive tasks on your Windows system? Do you want to streamline your workflow and save time? Look no further than Windows Task Scheduler, the built-in job scheduling tool in Windows. Whether you’re a developer, IT professional, or just someone looking to automate some basic tasks, this guide will provide you with everything you need to know to get started with Task Scheduler.

Understanding Task Scheduler and its Features

Task Scheduler is a built-in utility in Windows operating systems that allows users to schedule tasks and automate routine tasks on their computer. Some of the key features and benefits of Task Scheduler include the ability to schedule tasks to run at a specific time or when a specific event occurs, the ability to create complex tasks with multiple triggers and actions, and the ability to automate tasks using PowerShell scripts. Task Scheduler also provides detailed logging and notification features to help users monitor and troubleshoot their tasks.

Task Scheduler has been a standard component of Windows since Windows 98, and is supported on all modern versions of Windows, including Windows 10, Windows Server, and Windows Nano Server. While there are other job scheduling software options available, Task Scheduler is unique in that it is included with the operating system and does not require any additional software installation.

To effectively use Task Scheduler, it is important to understand some basic terminology such as tasks, triggers, actions, and conditions. A task is a set of instructions that describe what needs to be done, while a trigger is an event or condition that initiates the task. An action is the actual task that is performed, and a condition is a set of requirements that must be met before the task can be executed.

Creating Basic Tasks with Task Scheduler

One of the most common uses of Task Scheduler is to create basic tasks that automate routine tasks such as running backups or cleaning up files. Creating a basic task is easy using the Create Basic Task Wizard, which guides users through the process of setting up a new task.

To create a new task, users can open Task Scheduler and select the “Create Basic Task” option from the Action menu. The wizard will then prompt users to enter a name and description for the task, as well as select a trigger for when the task should run. Users can choose from a variety of triggers such as daily, weekly, or monthly, or they can set a specific time or event trigger.

Once the trigger has been set, users can then select the appropriate action for the task. This can include running a program, sending an email, displaying a message, or even starting a PowerShell script. After the action has been configured, users can review and test the task to ensure that it runs as expected.

In the event that a basic task encounters an issue or error, Task Scheduler provides detailed logging and notification features to help users troubleshoot the problem. By reviewing the task history and error logs, users can quickly identify and resolve any issues with their tasks.

Advanced Task Scheduling Techniques

Task Scheduler is a powerful tool that can handle a variety of tasks, from simple to complex. Here are some advanced techniques to help you get the most out of Task Scheduler:

Using the Task Scheduler API to create complex tasks: The Task Scheduler API allows you to create tasks programmatically using C++, C#, or Visual Basic. This can be useful if you need to create tasks dynamically or if you want to create tasks with complex triggers.

Working with batch files and PowerShell scripts: Task Scheduler can run batch files and PowerShell scripts as part of a task. This can be useful for automating tasks that require a series of commands or scripts to run.

Setting dependencies and prioritizing tasks: You can set up dependencies between tasks so that one task runs only after another task has completed. You can also prioritize tasks so that high-priority tasks run before low-priority tasks.

Configuring notifications and logging: Task Scheduler can send email notifications when a task completes or when an error occurs. You can also configure logging to keep track of task activity and diagnose problems.

Cross-platform workflows with Task Scheduler: While Task Scheduler is a Windows-specific tool, it can be used in conjunction with other tools to create cross-platform workflows. For example, you can use Task Scheduler to trigger a PowerShell script that runs on a Linux server.

Visualcron vs. Task Scheduler

Visualcron is a commercial job scheduling software that offers additional features and capabilities beyond those of Task Scheduler. Here’s a comparison of the two tools:

Overview of Visualcron job scheduling software: Visualcron is a powerful job scheduling software that includes features such as a drag-and-drop interface, ETL (Extract, Transform, Load) capabilities, and file transfer functionality.

Comparison of features and benefits to Task Scheduler: Visualcron offers many features that are not available in Task Scheduler, such as the ability to create complex workflows, run tasks on remote computers, and monitor task performance in real-time. However, Task Scheduler is a built-in tool in Windows and is therefore more widely available.Use cases for Visualcron vs. Task Scheduler: Visualcron is a good choice for organizations that need a robust job scheduling solution with advanced features. Task Scheduler is a good choice for smaller organizations or individuals who need basic scheduling capabilities built into Windows.

Frequently Asked Questions

W3C Working Draft 02 December 2014

This version:

http://www.w3.org/TR/2014/WD-task-scheduler-20141202/

Latest version:

http://www.w3.org/TR/task-scheduler/

Latest editor’s draft:

http://www.w3.org/2012/sysapps/web-alarms/

Previous version:

http://www.w3.org/TR/2013/WD-web-alarms-20130205/

Editors:

Mahesh Kulkarni, Samsung Electronics,
Co., Ltd, mahesh.kk@samsung.com

Former Editors:

Christophe Dumez, representing Intel and Samsung Electronics (Until January 2013 and mid-August 2014, respectively)

Repository:

We are on Github.

File a bug.

Commit history.

Copyright © 2014 W3C^® (MIT, ERCIM, Keio, Beihang), All Rights Reserved. W3C liability, trademark and document use rules apply.

Example use of the ScheduledTask API for adding, getting and removing and listening for the alarm clock use cases:

How to set an alarm 10 minutes from now?

    // https://example.com/serviceworker.js
    this.ontask = function(task) {
        alert(task.data.message);
        console.log("Task scheduled at: " + new Date(task.time));
        // From here on we can write the data to IndexedDB, send it to any open windows,
        // display a notification, etc.
    }

    // https://example.com/webapp.js
    function onTaskAdded(task) {
        console.log("Task successfully scheduled.");
    }

    function onError(error) {
        alert("Sorry, couldn't set the alarm: " + error);
    }

    navigator.serviceWorker.ready.then(function(serviceWorkerRegistration) {
        serviceWorkerRegistration.taskScheduler.add(Date.now() + (10 * 60000), {
            message: "It's been 10 minutes, your soup is ready!"
        }).then(onTaskAdded, onError);
    });
        

How to get all the scheduled tasks whose time is in the future?

    navigator.serviceWorker.getRegistration().then(function(registration) {
        registration.taskScheduler.getPendingTasks().then(function(tasks) {
            alert("There are " + tasks.length + " tasks set.");
        }, function(error) {
            alert("An error occurred getting the scheduled tasks.");
        });
    }, function(error) {
        alert("An error occurred getting the scheduled tasks.");
    });
        

How to remove a scheduled task?

    navigator.serviceWorker.getRegistration().then(function(registration) {
        var request = registration.taskScheduler.remove(id).then(function() {
                alert("Task removed");
            }, function(error) {
                alert("Sorry, can't remove the task.");
            });
    }, function(error) {
        alert("An error occurred getting the scheduled tasks.");
    });