Interprocess Communication

Re: Interprocess Communication

Through a dll (written in C++), doesn't work because each app has it's
own instances of the variables declared in the dll. Is there a way to
force one instance?

To this....the API would let you search for an existing instance of the
object and use that one instead of creating a new instance

--
Stéphane Richard
Senior Software and Technology Supervisor

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"John Norman" <reply@throughn ewsgrp.com> wrote in message
news:je4kgvs90p kuluqpqu0bdnelc qt9mcuqni@4ax.c om...[color=blue]
> I'm trying to pas data back and forth between a vb app, and a c++ app.
> I have tried several methods:
>
> Through a dll (written in C++), doesn't work because each app has it's
> own instances of the variables declared in the dll. Is there a way to
> force one instance?
>
> Windows messaging - I could only get it working by broadcast, then it
> calls Internet Explorer, and wierd stuff happens.
>
> FileMapping - I'm working on this method now, having trouble with some
> of the api's in C.
>
> Can anyone offer any suggestions?
>
> Thanks in Advance
>
> John Norman[/color]

Re: Interprocess Communication

Ok,
since you have full control of the CPP DLL and the VB App,
- this is how I do it

1) RegisterWindows Message using a unique string ID
- that gives you a 'unique' Windows Message Number
2) Broadcast on this number, and make all recipients reply
- sending back their hWnds
3) SendMessage using WM_COPYDATA to then now known hWnd(s)

If you can understand Delphi / Pascal then I could post you an example
that 'chats' - or a DLL that encapsulates it

On Mon, 07 Jul 2003 17:40:54 -0700, John Norman
<reply@throughn ewsgrp.com> wrote:
[color=blue]
>I'm trying to pas data back and forth between a vb app, and a c++ app.
>I have tried several methods:
>
>Through a dll (written in C++), doesn't work because each app has it's
>own instances of the variables declared in the dll. Is there a way to
>force one instance?
>
>Windows messaging - I could only get it working by broadcast, then it
>calls Internet Explorer, and wierd stuff happens.
>
>FileMapping - I'm working on this method now, having trouble with some
>of the api's in C.
>
>Can anyone offer any suggestions?
>
>Thanks in Advance
>
>John Norman[/color]

Re: Interprocess Communication

John Norman <reply@throughn ewsgrp.com> wrote in message news:<je4kgvs90 pkuluqpqu0bdnel cqt9mcuqni@4ax. com>...[color=blue]
> I'm trying to pas data back and forth between a vb app, and a c++ app.
> I have tried several methods:
>
> Through a dll (written in C++), doesn't work because each app has it's
> own instances of the variables declared in the dll. Is there a way to
> force one instance?
>
> Windows messaging - I could only get it working by broadcast, then it
> calls Internet Explorer, and wierd stuff happens.
>
> FileMapping - I'm working on this method now, having trouble with some
> of the api's in C.
>
> Can anyone offer any suggestions?
>
> Thanks in Advance
>
> John Norman[/color]

A pretty complete documentation on how to pass data between processes
can be found at the following URL:


Robert

Re: Interprocess Communication

Stephane,
Do you know which api's handle this?

Thanks
John

On Tue, 08 Jul 2003 00:57:08 GMT, "Stephane Richard"
<stephane.richa rd@verizon.net> wrote:
[color=blue]
>Through a dll (written in C++), doesn't work because each app has it's
>own instances of the variables declared in the dll. Is there a way to
>force one instance?
>
>To this....the API would let you search for an existing instance of the
>object and use that one instead of creating a new instance[/color]

Re: Interprocess Communication

This is a complete red herring

DLLs leech of the Data Area of their parent EXEs
- although they all share the same Code Area, they all have different
Data Areas - if they belong to different EXEs

There is just one curious exception, which seems to be memory mapped
files - I still have not got to the bottom of that.

Passing data between VB Apps (not VB to CPP) is pretty easy, you
simply use an AX EXE
- which _does_ have its own Data Area
- and hence that is 'shared' between anything using the EXE
(providing the instancing of the AX EXE has been correctly set up)

This is probably of little use for Inter-Language and App
communication - but nifty for VB to VB

On Tue, 08 Jul 2003 05:32:14 -0700, John Norman
<reply@throughn ewsgrp.com> wrote:
[color=blue]
>Stephane,
> Do you know which api's handle this?
>
>Thanks
>John
>
>On Tue, 08 Jul 2003 00:57:08 GMT, "Stephane Richard"
><stephane.rich ard@verizon.net > wrote:
>[color=green]
>>Through a dll (written in C++), doesn't work because each app has it's
>>own instances of the variables declared in the dll. Is there a way to
>>force one instance?
>>
>>To this....the API would let you search for an existing instance of the
>>object and use that one instead of creating a new instance[/color]
>[/color]