Need 16bit app to talk to 32bit app -DDE or OLE?

Posted on 1998-07-30
Last Modified: 2010-05-03
I have a 16bit VB4 app that needs to talk (using mostly string messages) to a 32bit C++ app. Windows messaging is limited (i believe?) and I am told DDE is very touchy. I have been suggested OLE but how? I don't know. I just need to get short strings between apps very quickly. What do I do?
Question by:rblackwell
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Expert Comment

ID: 1467300
Are the apps on the same machine? Is data flowing in both directions, or is the VB4 app exclusively sending data?

Author Comment

ID: 1467301
Both apps are on the same machine and data (string & Integer) is going in both directions. They will be combined in the future but time does not permitt.

Accepted Solution

cymbolic earned 30 total points
ID: 1467302
DDE is not touchy, and extremely easy to implement in VB.  It's fast and reliable, but of course needs both applications to be running before it works!  I've used it without fail to communicate and interoperate older mail systems that were not MAPI compliant running in W95, and it's really the interface of choice for 16 bit apps in Windows.  Don't believe the FUD factor comments used to migrate the development lemmings into the waiting arms of Microsoft's 32bit world of profit.

For instance, the following was all I needed after setting the properties on a textbox control to kick off an email message under GroupWise using DDE:

    'Create GroupWise SendMail String, as documented
    ' in GroupWise online help.
    sql$ = "SendMail(" & xx$ & "DTaylor" & xx$ & ";" & xx$ & FrmProgress.Caption & xx$ & ";" & xx$ & sql$ & xx$ & ")"
    Text1.LinkMode = 0
    'GroupWise server: Ofwin GroupWise Topic: Command
    Text1.LinkTopic = "Ofwin|Command"    ' Set link topic.
    On Error Resume Next
    Text1.LinkMode = vbLinkManual
    If Err <> 282 Then Text1.LinkExecute sql$ 'Send GroupWise SendMail Command

The only tricky part is digging out the specs for some other person's program to perform the DDE link.  This is usually a whole hell of a lot simpler than trying to pry hidden registry switches from proprietary MS apps, and since you are setting it up on both ends, there's no "hidden" tricks to be bartered from a third party bug producer on this one!

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