Powershell Call Assembly Delegate

Question

I have a dll assembly for our process control application, which I use load inside my powershell script.

The DLL contains a Delegate type that I need to use, delegate name is :

"X.Y.Delegate"

I have an another method in that DLL that should be called this way :

Method( delegatetype CallbackMethod)

So, I need to :

define a delegate in my script of type "X.Y.Delegate" for example $MyDelegate
define a callback method so that it gets invoked when a process event is triggered"

Note: I'm sorry if my question seems silly, I'm an ABSOLUTE Beginner.

What is your actual question? Are you asking how to implement these or for information as to which option is considered better? — masrtis, May 08 '13 at 18:50
Thanks for your reply :) I'm using it actually to minimize resources consumption. rather than checking 10000 of tag values every minute, check what have been changed, I can subscribe to an eventhandler, create my own scriptblock to be executed when event occurs. This way I won't scan my 10000 tags, I would be called back whenever something changes. This is my understanding to the topic, if I'm wrong I'd be grateful if you correct me. Thanks again. — Ahmed Atef, May 09 '13 at 08:02

dugas · Accepted Answer · 2013-05-09T20:18:09.250

Update:

After reading your comment and reading your question more closely, I think you might be looking to utilize asynchronous event handling. Below is an example that listens for events until a timeout is reached and then exits. This example assumes you can change your assembly to add an event.

A class that generates events:

namespace ClassLibrary1
{
 public class Class1
 {
  public event EventHandler SomeEvent;

  protected void OnSomeEvent(EventArgs e)
  {
   var someEvent = SomeEvent;

   if (someEvent != null)
   {
    SomeEvent(this, e);
   }
 }

 public void SomeMethod()
 {
  Task.Run(() =>
  {
   for (int i = 0; i < 3; i++)
   {
    Thread.Sleep(3000);
    OnSomeEvent(EventArgs.Empty);
    }
   });
  }
 }
}

Powershell:

# Load up your .net assembly
add-type -path .\Class1.cs 

$x = new-object ClassLibrary1.Class1

$sourceIdentifier = "SomeEvent"

# Register event
$eh = Register-ObjectEvent -SourceIdentifier $sourceIdentifier -InputObject $x -EventName SomeEvent

$x.SomeMethod()

while ($true)
{
 Write-Host "Waiting for event..."
 $event = Wait-Event -SourceIdentifier $sourceIdentifier -Timeout 10

 if ($event -eq $null) 
 {
  Write-Host "No event received for 10 seconds." 
  break 
 }

 # Do processing here
 Write-Host "Processing event..."
 $event

 # Remove event from queue
 Remove-Event -SourceIdentifier $sourceIdentifier
}

Unregister-Event -SourceIdentifier $sourceIdentifier
Write-Host "Done processing events."

Thanks a lot, it DOES work. The idea I think is the variable "ScriptBlock" that encapsulates the block to be executed. I got Powershell stops responding when My application starts calling back the scriptblock, but I can see now in my application server log that handler starts, a handler object is sent, means that I'm on the right direction. Could you please tell me how can powershell responds to my application callbacks after the script has been executed ? I run the script on ISE, debug, when my application server calls me back powershell stops. should I see the output in my console ? Thanks — Ahmed Atef, May 09 '13 at 07:56

Powershell Call Assembly Delegate

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