Invoke, BeginInvoke / EndInvoke or InvokeAsync? what to use when and why?

Question

In reference to using PowerShell in VB or C# via System.Management.Automation

I know that Invoke runs synchronously, and using BeginInvoke / EndInvoke means you can do same thing asynchronously.

But I noticed today that there is also InvokeAsync

Can anyone explain to me the benefit of using this over the other methods and if there is a particular method I should be using?

Most examples I see use Invoke for basic commands and BeginInvoke / EndInvoke for longer running tasks.

Just want to learn best approach and have an understanding of what to use when as can't find much documentation on InvokeAsync like I could the others.

update: Quick examples below of same code using Invoke or BeginInvoke/EndInvoke

Thanks

    Dim powershell As PowerShell = PowerShell.Create()
    powershell.AddCommand("Get-Process")

    Dim results = powershell.BeginInvoke

   Do While results.IsCompleted = False

            ' wait whilst command completes

    Loop


    For Each result As PSObject In powershell.EndInvoke(results)

      UpdateTextBox("Process Name: " & result.Members("ProcessName").Value & " Process ID: " & result.Members("Id").Value & vbCrLf)

    Next result

or

   Dim powershell As PowerShell = PowerShell.Create()
    powershell.AddCommand("Get-Process")

    Dim results = powershell.Invoke


    For Each result As PSObject In results

        UpdateTextBox("Process Name: " & result.Members("ProcessName").Value & " Process ID: " & result.Members("Id").Value & vbCrLf)

    Next result

Does this answer your question? [What are the strengths of the IAsyncResult pattern?](https://stackoverflow.com/questions/12750532/what-are-the-strengths-of-the-iasyncresult-pattern) — Charlieface, Jan 18 '21 at 22:34
If you are using the Tasks Parallel Library and `async`/`await` in the rest of your code then you should use `InvokeAsync`, which returns a `Task>`. If you're not using async code via the TPL elsewhere then don't do it here either. — jmcilhinney, Jan 18 '21 at 23:22
Added example of some basic code used above, this can be used with the three methods I mentioned. I am not using TPL — Darren Rose, Jan 18 '21 at 23:36

score 0 · Answer 1 · answered Jan 19 '21 at 03:05

If you're using the TPL throughout your app then use InvokeAsync. You can await the call or not, just as you can for any other async method.

If you need an invocation to be synchronous, e.g. your background operation has to wait to get input from the UI, then use Invoke.

If you don't need an invocation to be synchronous then use BeginInvoke. If you need to get data back then use EndInvoke as well. For instance, if you are performing an operation in the background and updating a ProgressBar, you should call BeginInvoke rather than Invoke. That's because there's no need for the background work to wait while the that update happens. You don't need any result though, so there's no need to call EndInvoke.

Invoke, BeginInvoke / EndInvoke or InvokeAsync? what to use when and why?

1 Answers1