C# -Four Patterns in Asynchronous execution

Question

I heard that there are four patterns in asynchronous execution.

There are four patterns in async delegate execution: Polling, Waiting for Completion,

Answer 1

This code is Polling:

while (!ar.IsCompleted)

That's the key, you keep checking whether or not it's completed.

THis code doesn't really support all four, but some code does.

Process fileProcess = new Process();
// Fill the start info
bool started = fileProcess.Start();

The "Start" method is Asynchronous. It spawns a new process.

We could do each of the ways you request with this code:

// Fire and forget
// We don't do anything, because we've started the process, and we don't care about it

// Completion Notification
fileProcess.Exited += new EventHandler(fileProcess_Exited);

// Polling
while (fileProcess.HasExited)
{

}

// Wait for completion
fileProcess.WaitForExit();