Subject: Re: Callback function calls across process? - msg#00015

Another alternative is to use SendMessage with WM_COPYDATA. The wParam contains
the HWND of the window passing the data, and the LPARAM is a pointer to a
COPYDATASTRUCT. In the other process, write a WM_COPYDATA handler to fetch the
data and perform the callback functions.

jcc


----- Original Message ----
From: Paul Yao <paul@xxxxxxxxxxx>
To: windowsce-dev@xxxxxxxxxxxxxxx
Sent: Monday, November 6, 2006 9:20:47 AM
Subject: RE: [windowsce-dev] Callback function calls across process?

The ::SendMessage is guaranteed to work across process boundaries.

I wonder if you are having problems because of the parameters that you
are passing. I am going to make a guess here -- that you are including
one (or more) pointers in your SendMessage call. If this is true, then
it is the pointer -- and not the function call -- that is the problem.

To fix this problem, you can put your pointers into a shared memory
area. To allocate memory in a shared memory area, you need to call a
combination of several functions: (1) CreateFileMapping, and (2)
MapViewOfFile. Once you have allocated this shared memory area, copy
your parameters to this memory. Then use a pointer to this memory to
perform your inter-process SendMessage.

I made a few guesses here, so perhaps this will help or perhaps not. One
thing is clear, though: if you are using SendMessage, that function is
guaranteed to work across process boundaries.

Good luck!

Best,
Paul

-----Original Message-----
From: windowsce-dev@ yahoogroups. com
[mailto:windowsce-dev@ yahoogroups. com] On Behalf Of Jain, Vatsalya
Sent: Sunday, November 05, 2006 9:20 PM

Hi all.

I need some advice.

My current requirement is to invoke some functions using callback
mechanism, and the functions to be called are present in a dll while the
calling code is in an exe. ( ire I need to make an IPC call for the
same)

I have been able to figure out callback could be used in the same
process using ::SendMessage( hwnd,...) call , but this API wont work
for across process calls.

Can anyone suggest how to go about the Inter process calls ?

Thanks in Advance,
Regards,
Vatsalya






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