Question: Using STA component in threadpool via delegate.BeginInvo

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Leon - 20 Oct 2006 07:49 GMT

Hi,

I have a couple of questions relating to STA component that has been bugging
me.

If I have a STA component and I want to call one of its methods, which takes
some times to complete and so I want to run it on a threadpool by using
delegate.BeginInvoke().

Questions:
1) What kind of Apartment are the threads in the threadpool?
2) In legacy COM programming, I need to manually marshal the COM interface
pointer to the other Apartment.

If I simply pass the interface in .Net as a parameter when I call the
delegate.BeginInvoke(), will .Net marshals the interface for me?

If not, how do I to do this correctly?

Thanks.

Leon

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Carl Daniel [VC++ MVP] - 20 Oct 2006 17:34 GMT

> Hi,
>
[quoted text clipped - 9 lines]
> Questions:
> 1) What kind of Apartment are the threads in the threadpool?

Generally speaking, they're not in any apartment. I would assume, however,
that they'll automatically enter the MTA if necessary. That doesn't help
with your STA component though.

> 2) In legacy COM programming, I need to manually marshal the COM interface
> pointer to the other Apartment.
>
> If I simply pass the interface in .Net as a parameter when I call the
> delegate.BeginInvoke(), will .Net marshals the interface for me?

I don't think so. Even if it did, it wouldn't do what you want anyway,
since the marshalled interface pointer would simply marshall the call back
into the thread that created the component in the first place - that's the
only thread a STA component can run on.

If you have a STA component, you really don't have any practical alternative
to simply calling all of it's member functions on your UI thread.

-cd

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Question: Using STA component in threadpool via delegate.BeginInvo

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