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'[OT:] Is DDE that slow?'
2005\04\29@014357 by John Pearson

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I am trying to incorporate DDE into a  MS VC++ MFC program. The program receives serial input, and I want to pass it along to Excel via DDE. As soon as I make the first data poke to Excel, my program slows down so much I can see each serial port character displayed on the screen one by one, instead of a line of data appearing instantly (9600 baud), even while there is no more data being sent to Excel. If I break the DDE connection, the program resumes normal speed again. Is this typical of DDE, or is something wrong somewhere. Or is there some kind of messaging continuing between Excel and my app even while there is no DDE data exchanges occuring?

Please suggest I use COM only if you have some well documented stand-alone VC code examples I can incorporate into an MS VC++ MFC app.

Thanks
John

2005\04\29@085045 by Gerhard Fiedler

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John Pearson wrote:

> I am trying to incorporate DDE into a  MS VC++ MFC program. The program
> receives serial input, and I want to pass it along to Excel via DDE. As
> soon as I make the first data poke to Excel, my program slows down so
> much I can see each serial port character displayed on the screen one by
> one, instead of a line of data appearing instantly (9600 baud), even
> while there is no more data being sent to Excel. If I break the DDE
> connection, the program resumes normal speed again. Is this typical of
> DDE, or is something wrong somewhere.

It's been ages since I've done something with DDE, but I never had this
effect.

> Please suggest I use COM only if you have some well documented
> stand-alone VC code examples I can incorporate into an MS VC++ MFC app.

I don't have any links, but if you want to work with MFC, "Programming
Windows with MFC" by Jeff Prosise is one of the standards. It includes many
examples, among them the use of ActiveX/COM.

But it shouldn't be difficult to find online tutorials. It's not that
difficult to figure out either. You use the IDE to add an ActiveX object to
your project, which creates a wrapper class. Then you place it on a dialog
and use it. Most cases are pretty straightforward -- and easier to
implement than DDE.

Maybe this here (even though the links to the figures seem to be broken)
http://www.mclibrary.edu.mn/itbooks/activex_programming_with_visual_c++/ch15.htm#Heading5

Or this http://www.codeproject.com/com/webbrowser.asp

Gerhard

2005\04\29@085547 by John J. McDonough

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It may be that Excel is that slow, but DDE in general is not.  Obviously,
you can make anything slow if you code it to be, but it looks to me as if
DDE is relatively quick.  I have a VC++ application that accepts data from
other applications which are usually VB.  The transfer time is only
perceptible if the exchange involves hundreds of records.

I know, I know, it should be COM, but the other apps tend to be garage shop
applications and DDE is a helluva lot easier to explain.

--McD

{Original Message removed}

2005\04\29@124656 by Bob Ammerman

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DDE is _very_ slow.

It is also considered obsolete.

You want to use OLE Automation (COM) instead.

You should be able to find hundreds of example programs for using COM to
drive Excel from VC on the Web. There are also some good examples in
Microsoft's MSDN site.

Bob Ammerman
RAm Systems

{Original Message removed}

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