Unable to pass custom method to ElapsedEventHandler() as an argument

Question

I am working on a windows service which will look for backup files in a particular folder. When it finds one the service will move all the backup files from that location and move them to an archived folder.

I have used FileSystemWatcher before but since it doesn't work on Servers I am using DirectoryInfo to look for the files.

The requirement is to run this service at every 5 minutes interval to look for any new backup files coming in.

I am stuck with the timer implementation.

Following is my code:

I want to call MoveToProcessed(processed) method from the ElapsedEventHandler. but I am getting error CS0149 - Method name expected.

protected override void OnStart(string[] args)
{
    DirectoryInfo dir = new DirectoryInfo(backupdirectory);

    // Other unrelated code omitted

    // Move all the Backup files to Processed folder at certain intervals.
    createOrderTimer = new System.Timers.Timer();

    //***** ERROR ON THE FOLLOWING LINE *****
    createOrderTimer.Elapsed += new ElapsedEventHandler(MoveToProcessed(processed));
    //***************************************

    createOrderTimer.Interval = 300000; // 15 min
    createOrderTimer.Enabled = true;
    createOrderTimer.AutoReset = true;
    createOrderTimer.Start();
}

private void MoveToProcessed(string processed)
{
    // Code here backs up and restores files
}

Answer 1

You can easily call a method from an event handler, but the event handler method itself must match a specific signature. For the System.Timers class, it should look something like this:

private static void Timer_Elapsed(object sender, System.Timers.ElapsedEventArgs e)

So you can simply create a method with this signature, assign it as an event handler, and then call your method from there:

// Elapsed event handler calls our other method
private static void CreateOrderTimer_Elapsed(object sender, System.Timers.ElapsedEventArgs e)
{
    // Not sure what the string argument represents, or how it should be set
    MoveToProcessed("some string");
}

// We can assign the event handler above when creating the Timer:
protected override void OnStart(string[] args)
{
    var createOrderTimer = new System.Timers.Timer
    {
        Interval = TimeSpan.FromMinutes(15).TotalMilliseconds,
        AutoReset = true
    };

    createOrderTimer.Elapsed += CreateOrderTimer_Elapsed;
    createOrderTimer.Start();
}