Re: Ada in control - Win32 GUI - Possible?

[jerry@jvdsys.nextjk.stuyts.nl (Jerry van Dijk)]

In article <345F4B6A.7FDA@gsfc.nasa.gov> Stephen.Leake@gsfc.nasa.gov writes:

>Dave Smith wrote:
>>
>> <snip>
>>
>>    Can an Ada program be in control of a Win32 GUI?
>>

<snip>

>I'm not clear what you mean by "in control". The DLL has an init
>procedure called when it is loaded; that does the Ada elaboration. Ada
>finalization takes care of cleaning up. What more "control" do you need?

As I understand the question:

a) the main program is actually the middleware layer, in Ada, rebuild for W32

b) this main program, when ready, starts the client program in VB

c) the client then wants to use the middleware layer functionality

d) when the client finishes running, the middleware layer gets back
   control and finishes.

e) due to well-known constrains, redesign is not feasible

how to archieve this ?

Unknown is whether there is just one client (and number of instances)
or why (if there is 3 months time) the client isn't also written using
Ada (possibly using an GUI builder).

However, if I am correct in the above, the question has little to do
with Ada. The real question is how to mold an existing application
architecture to fit into the Win32 environment.

Can this be done ? Yes, of course, in a lot of ways. How, that would
depend on a lot of other parameters which are unknown to us.

In general though I would suggest running the middleware layer as a
invisible process, starting the client in the foreground. Communication
by whichever means are most appropiate (lots of choices here). Client
before going down informing the middleware, which will then also
shutdown. Although, as Stephen suggested, running the middleware
from a DLL is also possible, although feasebility would depend on
its current design.

However, there are probably a lot of -to us- unknown complexities and
requirements here, so a specific answer would require a lot more info
and study.

Best advise, if my assumptions are correct, is to call in a application
architect with Ada and Win32 experience.

--

-- Jerry van Dijk | Leiden, Holland
-- Consultant     | Team Ada
-- Ordina Finance | jdijk@acm.org