How to create an asynchronous method

Question

I have simple method in my C# app, it picks file from FTP server and parses it and stores the data in DB. I want it to be asynchronous, so that user perform other operations

Answer 1

In Asp.Net I use a lot of static methods for jobs to be done. If its simply a job where I need no response or status, I do something simple like below. As you can see I can choose to call either ResizeImages or ResizeImagesAsync depending if I want to wait for it to finish or not

Code explanation: I use http://imageresizing.net/ to resize/crop images and the method SaveBlobPng is to store the images to Azure (cloud) but since that is irrelevant for this demo I didn't include that code. Its a good example of time consuming tasks though

private delegate void ResizeImagesDelegate(string tempuri, Dictionary versions);
private static void ResizeImagesAsync(string tempuri, Dictionary versions)
{
    ResizeImagesDelegate worker = new ResizeImagesDelegate(ResizeImages);
    worker.BeginInvoke(tempuri, versions, deletetemp, null, null);
}
private static void ResizeImages(string tempuri, Dictionary versions)
{
    //the job, whatever it might be
    foreach (var item in versions)
    {
        var image = ImageBuilder.Current.Build(tempuri, new ResizeSettings(item.Value));
        SaveBlobPng(image, item.Key);
        image.Dispose();
    }
}

Or going for threading so you dont have to bother with Delegates

private static void ResizeImagesAsync(string tempuri, Dictionary versions)
{
    Thread t = new Thread (() => ResizeImages(tempuri, versions, null, null));
    t.Start(); 
}