----- Original Message -----
From: "Jim Sievert" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Friday, September 12, 2003 6:17 PM
Subject: Re: [ADVANCED-DOTNET] Object identities, marshaling issues and
interoperability
> Besides your solution, perhaps the GIT may help. I'm not 100% sure about
> this, though. Assuming you're wrapping your COM object, the creation of
> such a wrapper could register the object in the GIT. The question is
> whether or not you can register the same object multiple times (from two
> different apartments no less). If you can, the same cookie should be
> returned. I believe you can use this cookie as your Hashtable key?
Surely. Thanks for fresh idea about GIT, Jim, I'll try it.
>
> > -----Original Message-----
> > From: Dmitry Shaporenkov [mailto:[EMAIL PROTECTED]
> > Sent: Friday, September 12, 2003 7:55 AM
> > To: [EMAIL PROTECTED]
> > Subject: Re: [ADVANCED-DOTNET] Object identities, marshaling
> > issues and interoperability
> >
> >
> > ----- Original Message -----
> > From: "Jim Sievert" <[EMAIL PROTECTED]>
> > To: <[EMAIL PROTECTED]>
> > Sent: Friday, September 12, 2003 4:20 PM
> > Subject: Re: [ADVANCED-DOTNET] Object identities, marshaling
> > issues and interoperability
> >
> >
> > > Your best bet is to compare objects based on their
> > IUnknowns. You can
> > > use
> > > GetIUnknownForObject() for this (don't forget to call
> > Release when you're
> > > done).
> >
> > This is exactly what I'm trying to do.
> >
> > > Because these IUnknown values are Apartment relative, you
> > just can't
> > > plop the IUnknown as a key in the Hashtable. You're going
> > to have to
> > > do some work -- probably by specializing the Hashtable...
> >
> > Yes, but I can't figure out how this work could be done.
> > May be I need to marshal IUnknown to a stream and
> > then use contents of the stream as an identity? If the
> > contents of the stream is apartment-independent, this will probably
> > work, but such a solution is obviously inefficient. Or do
> > I need something else?
> >
> > COM experts, please advise!
> >
> > > -----Original Message-----
> > > From: Dmitry Shaporenkov [mailto:[EMAIL PROTECTED]
> > > Sent: Friday, September 12, 2003 4:25 AM
> > > To: [EMAIL PROTECTED]
> > > Subject: [ADVANCED-DOTNET] Object identities, marshaling issues and
> > > interoperability
> > >
> > >
> > > Hi all,
> > >
> > > I need help in a problem concerning COM/.NET interoperability in a
> > > multithreaded application. The application (written in
> > > C#) uses an external component which exposes COM-based
> > object model.
> > > Let's say 'Item' is an object of the model, item has a __CComObject
> > > type. Items are accessed via calls to the component like
> > the follows:
> > >
> > > ....
> > > Item anItem = externalObject.GetItem ("MyItem");
> > > ....
> > >
> > > During startup a worker thread is running to collect some
> > information
> > > about items and store it in a hashtable (using items as the keys):
> > >
> > > ....
> > > Hashtable theCache = new Hashtable ();
> > > theCache [anItem] = <something>;
> > > ...
> > >
> > > The information is then used from code executing in the UI thread:
> > >
> > > ...
> > > Item anItem = externalObject.GetItem ("MyItem");
> > > <something> = theCache [anItem]; // Oops. This does not work ...
> > >
> > > The problem is that, because UI thread lives in a STA and
> > the worker
> > > thread executes in another apartment, the UI thread gets different
> > > wrapper than the worker thread, since items are marshalled across
> > > apartments. I realize that this is normal behavior.
> > However, I need a
> > > way to identify items in a thread-independent fashion. Items
> > > themselves do not have any properties which might serve as
> > a reliable
> > > unique identifiers.
> > >
> > > So, the question is, how such problems are resolved? May be
> > there is
> > > still a way to get apartment-independent identifier of the
> > object? I
> > > am not a COM guru, but I took a look at
> > > System.Runtime.InteropServices.Marshal class and found nothing
> > > similar.
> > >
> > > Any advices / references will be greatly appreciated. Thanks in
> > > advance.
> > >
> > > Regards,
> > > Dmitry Shaporenkov
> > > mailto:[EMAIL PROTECTED]
> > >
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