How can I schedule tasks in a WinForms app?

Question

QUESTION: How can I schedule tasks in a WinForms app? That is either (a) what is the best approach / .NET classes/methods to use of (b) if there is an open source component that does this well which one would be recommended.

BACKGROUND:

• Winforms app (.NET v3.5, C#, VS2008)
• I'm assuming I will run the winforms application always, and just minimise to the system tray when not in use
• Want a simple approach (didn't want to get into separate service running that UI winforms app talks to etc)
• Want to be able to let the user select how often to schedule the sync (e.g. hourly, daily - pick time, etc)
• Ability to at the times when the scheduler fires to run a chunk of code (assume it could be wrapped as a backgroundworker task for example)
• The application is always running & appears in the system tray

Answer 1

There's actually something directly built into Windows that will do just that. It's called the Windows Task Scheduler! Rather than having a Windows application that sits and waits for the right time to run a piece of code, you'd be better off just using an underlying system utility and storing the piece of code to run in a separate executable: it's easier and more efficient.

I've used the Task Scheduler before to configure my applications to start on a pretty specific schedule. The best way to do it out of a .NET application is to use this handy little library.

Basically, to accomplish what you've stated in your question, you need to make a Windows application that provides a GUI. This GUI should have options that regulate the creation and alteration of a Task. The Task should launch the code you have to run (you should store it in a separate executable, probably as a WinForms app that's transparent and, thus, hidden.)

Here's some code from the CodeProject article of the library itself that illustrates how to create a task:

//Get a ScheduledTasks object for the local computer.
ScheduledTasks st = new ScheduledTasks();

// Create a task
Task t;
try {
    t = st.CreateTask("D checker");
} catch (ArgumentException) {
    Console.WriteLine("Task name already exists");
    return;
}

// Fill in the program info
t.ApplicationName = "chkdsk.exe";
t.Parameters = "d: /f";
t.Comment = "Checks and fixes errors on D: drive";

// Set the account under which the task should run.
t.SetAccountInformation(@"THEDOMAIN\TheUser", "HisPasswd");

// Declare that the system must have been idle for ten minutes before 
// the task will start
t.IdleWaitMinutes = 10;

// Allow the task to run for no more than 2 hours, 30 minutes.
t.MaxRunTime = new TimeSpan(2, 30, 0);

// Set priority to only run when system is idle.
t.Priority = System.Diagnostics.ProcessPriorityClass.Idle;

// Create a trigger to start the task every Sunday at 6:30 AM.
t.Triggers.Add(new WeeklyTrigger(6, 30, DaysOfTheWeek.Sunday));

// Save the changes that have been made.
t.Save();
// Close the task to release its COM resources.
t.Close();
// Dispose the ScheduledTasks to release its COM resources.
st.Dispose();

NOTE: The priority option never worked for me, always crashing the app. I recommend you leave it out; usually, it doesn't make that big a difference.

There are more code samples on the article page, some of which show how to change the settings of a Task, list all Scheduled Tasks, etc.