inline
 
> HI Brian
>
> Thanks for replying and Sorry for the delay in the follow up.
>
> Each instance of the poolable component B creates an instance of the
third
> party apartment threaded dll C, so i'm not getting what you mean whey
you
> say that all the poolable components are using the same instance of C.
> Again, my understanding of threading models is a bit flaky so i might
be
> missing something obvious.
>
[Brian Muth] That's not what I meant. Each B has its own instance of C,
but C is apartment-threaded. There is one thread to server all C
instances. Ergo if two or more instances of B call their C instance,
each instance of B has to wait until C's thread becomes available.
 
> Another question again regarding the protection of the global
variables.
> Here again, each instance of B that is created in turn creates an
instance
> of C and keeps it as part of an instance specific variable. So in this
> case also, do I need to use a critical section when i instantiate that
> instance specific state in the ObjectControl_Activate method ??
>
[Brian Muth] My answer is the same. Every time you access your global
variables (in this case the interface pointer to C) you must protect it
with some form of synchronization.

> Another question here, how do i have a global instance of a variable
in
> ATL in the COM+ environment or without it ?
>
[Brian Muth] Standard C++ global variable will do.

> Thanks again
> Rahul
>
> -----Original Message-----
> From: Brian Muth [mailto:bmuthSTRAIGHTTHROUGH.COM]
> Sent: Thursday, April 04, 2002 10:48 PM
> To: DCOMDISCUSS.MICROSOFT.COM
> Subject: Re: Problem in threading model dep in COM+
>
>
> Inline
>
> >
> > We have three layers of calls for a component.
> >
> > We have one poolable component(say B) which is neutral threaded and
is
> > marked for pooling in COM+. The ObjectControl_Activate of this
> poolable
> > component instantiates a third party apartment threaded dll(say C)
and
> > keeps the instance alive as one of its member variables till the
> > application that contains the poolable component in COM+ is shut
down.
> > This third party dll basically connects through TCP/IP calls using
> Winsock
> > to the third party site to download information (this is not a dll
to
> wrap
> > around a web-service, it uses Winsock). You can say that this
poolable
> > component mimics a connection pool. The third party dll, C, is not
> placed
> > in COM+.
> [Brian Muth] So basically all the pooled B components share the same
> apartment threaded object C. Unless the B components are doing a lot
of
> work outside of C, I fail to see how this can scale effectively.
> Essentially all the B components have to take turns using C.
>
> > This poolable component is called by other apartment threaded
> components
> > which utilize connections from the connection pool.
> >
> > I would like to know whether there are any gotchas involved in
having
> this
> > kind of setup.
> [Brian Muth] I don't think there are any problems with this design,
> other than the fact that you are not really pooling the C objects.
>
> > As in, are there any issues in instantiating an apartment threaded
> object
> > from a neutral threaded component which is pooled in COM ?
> > Are there any problems in accessing this apartment threaded object
> whose
> > instance is kept alive in the neutral threaded component from
another
> > apartment threaded application ?
> [Brian Muth] The proxy-stub should to the right thing for you.
>
> > Should i use a critical section in the ObjectControl_Activate part
of
> the
> > neutral threaded component B, when I instantiate the third party dll
?
> [Brian Muth] Any global variables (ie. the interface to the C object)
> needs to be protected through some kind of synchronization.
>
> > Should I use a critical section when I use the third party dll from
> any
> > method in the neutral threaded component ?
> >
> [Brian Muth] No.
>
> > I'm not sure about the threading models in COM and was hoping
someone
> > could help me out.
> >
> > I'm not sure if this question can be posted in this mailing list. If
> it
> > cannot then i'd be grateful if someone could re-direct me to the
> > appropriate separate mailing list.
> >
> [Brian Muth] You are in the right place.
>
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