communication between the website and C# winforms application
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We have a Website (hosted somewhere) and C# Application (which is installed on my PC). I need to accomplish the following:

1. Customers fill up the form on the website, i.e. the task is "created"
2. C# Application immediately receives this data from the website and process it
3. The result is sent back to the server, i.e. "task accomplished" message
4. The website updates status regarding this task

How do you build this kind of link between the website and an app?

In the past I've used TCPListener to communicate between two C# apps. I'm also familiar with the UDPlistener and such.. Will this knowledge be of some use? The website is going to be build on the PHP. 

Some tips and advises are appreciated. Thanks.