COM Connection points and C# delegates

[lallous]

Hello

I am not very experienced with this issue and would your opinion on
whether it is healthy or not:


1) I created an ATL COM object (say MyCOM):
- that supports connection points
- that exposes couple of methods such as:
BeginOperation()
GetInformation()
- Exposed some events in the _IMyCOMEvents interface which was created
automatically by the wizard, such as:
OnNewItem()
OnProgressItem()
OnEndItem()


2) Implemented the connection points, etc...


Some information about BeginOperation():


1) It takes some initial parameters and stores them in the class member
variables
2) It creates a thread (CreateThread API), passing "this" as context
3) returns to the caller


The thread proc of BeginOperation():
1) do some lenghty operations (like file copying)
2) while doing the operations, fire the events when needed:
Fire_OnItemProgress() ....


I wanted to test this COM from C#, so:


1)Added reference to the COM
2)created a new instance of the object in the form' s constructor
3)Added new delegates to the object's OnNew, OnEnd, ...
The delegates updates the screen such as:
void OnNewItem(int itemNo)
{
StatusLabel.Text = "Currently processing item #" + itemNo.ToString();



}


etc...

Now, I am facing some weird issues:
1)sometimes, events are called, but only one line is being executed,
and then directly another event is being fired, w/o the first one
finishing
2)if application is ran w/ the debugger, it looks like the screen is
not updated as if some events are not triggered.


Please advise if this is the correct way of doing this.


Regards,
Elias

 

[Willy Denoyette [MVP]]

Note that doing so, you will have to marshal the update of the UI to the UI
thread, your event handlers do run on an auxiliary thread (the one created
in your component), so you may not access the UI elements directly. Check
the docs on Control.BeginInvoke and Invoke.

Willy.

| Hello
|
| I am not very experienced with this issue and would your opinion on
| whether it is healthy or not:
|
|
| 1) I created an ATL COM object (say MyCOM):
| - that supports connection points
| - that exposes couple of methods such as:
| BeginOperation()
| GetInformation()
| - Exposed some events in the _IMyCOMEvents interface which was created
| automatically by the wizard, such as:
| OnNewItem()
| OnProgressItem()
| OnEndItem()
|
|
| 2) Implemented the connection points, etc...
|
|
| Some information about BeginOperation():
|
|
| 1) It takes some initial parameters and stores them in the class member
| variables
| 2) It creates a thread (CreateThread API), passing "this" as context
| 3) returns to the caller
|
|
| The thread proc of BeginOperation():
| 1) do some lenghty operations (like file copying)
| 2) while doing the operations, fire the events when needed:
| Fire_OnItemProgress() ....
|
|
| I wanted to test this COM from C#, so:
|
|
| 1)Added reference to the COM
| 2)created a new instance of the object in the form' s constructor
| 3)Added new delegates to the object's OnNew, OnEnd, ...
| The delegates updates the screen such as:
| void OnNewItem(int itemNo)
| {
| StatusLabel.Text = "Currently processing item #" + itemNo.ToString();
|
|
|
| }
|
|
| etc...
|
| Now, I am facing some weird issues:
| 1)sometimes, events are called, but only one line is being executed,
| and then directly another event is being fired, w/o the first one
| finishing
| 2)if application is ran w/ the debugger, it looks like the screen is
| not updated as if some events are not triggered.
|
|
| Please advise if this is the correct way of doing this.
|
|
| Regards,
| Elias
|
|