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DDE (Dynamic Data Exchange) DDEML

    Question

  • Do we know if the subject will be supported in Windows 7?

    We use DDE quite often for industrial applications; it is still very reliable, and simple to use.

    Regards,
    TM
    Sunday, February 01, 2009 5:58 PM

Answers

  • Well, the Explorer uses DDE to open Office documents (supposed you open the document from the explorer window).
    Say you have Excel 2007 installed, double clicking on a xlsx file will start excel and initiate a DDE open transaction. Now, in Excel you can set an option to ignore DDE requests from other applications (that is not acting as a DDE server). If you set this option to ignore DDE requests you will see that Excel fails to open the document as requested by explorer open.
    PS. Excel options are under the Office button (left top corner), click Excel Options at the bottom of the menu, select advanced and select "Ignore other applications that use DDE "

    Rest assured DDE is just like COM not going away any soon.
    Friday, February 06, 2009 6:29 PM

All replies

  • DDE Share is a tool for managing the way programs communicate and share data over a network. DDE Share is not available in this version of Windows because it has been replaced by other methods for communicating and sharing data among computers.
    Carey Frisch
    Sunday, February 01, 2009 6:28 PM
  • Hello Carey - 

    thanks for your response.

    We use DDE only for 'local' communication, within the same computer.  DDE across a network ("Network DDE", or "NetDDE") has never been reliable, and we have never had a need for it (we use other communication protocols for 'box to box' comm).

    I was just curious about support in Windows 7; I see the "DDEML.DLL" library still exists in the System32 folder.  I just can't get a DDE client to connect to a DDE server.  I didn't see a service that I could enable to allow DDE.
    Sunday, February 01, 2009 6:32 PM
  • Can anyone say definitively whether DDE will be supported?

    Or, how can I contact MS directly to ask?

    Regards,
    Tom McCray
    Friday, February 06, 2009 3:31 PM
  •  DDE is still supported on Vista and on W7. Whether it works depends on the (security) context, for instance DDE cannot be used between user applications and services, when both, client and server, are running in the same security context there should be no issue.
    Friday, February 06, 2009 4:42 PM
  • Willy - Thanks for your reponse!

    We will always be within the same 'context' (just a PC running Windows, with a couple of Apps communicating via DDE).

    Now, for my next dumb question; Any ideas on what I would need to 'enable' to allow DDE to function in Win 7 beta?

    I'd like to be able to 'empirically' verify DDE works in the Windows 7 beta...

    I've looked all through the the "Local Security Policy", and didn't see anything that seemed applicable? (To be honest, I've never had to even go in to the "Local Security Policy", so it's all kind of foriegn to me anyway...

    Any suggestions are greatyly appreciated!
    Friday, February 06, 2009 5:57 PM
  • Well, the Explorer uses DDE to open Office documents (supposed you open the document from the explorer window).
    Say you have Excel 2007 installed, double clicking on a xlsx file will start excel and initiate a DDE open transaction. Now, in Excel you can set an option to ignore DDE requests from other applications (that is not acting as a DDE server). If you set this option to ignore DDE requests you will see that Excel fails to open the document as requested by explorer open.
    PS. Excel options are under the Office button (left top corner), click Excel Options at the bottom of the menu, select advanced and select "Ignore other applications that use DDE "

    Rest assured DDE is just like COM not going away any soon.
    Friday, February 06, 2009 6:29 PM
  • This article appears to imply that DDE is deprecated in Windows 7.  It also appears that you may need to make an addition to the registry in some cases to make it work:
    http://msdn.microsoft.com/en-us/library/cc144171(VS.85).aspx
    Tuesday, October 13, 2009 4:12 PM
  • wow...this article says to use IDropTarget. I use an application which allows me to download DDE capability, and creates an add-on for Excel. It all worked fine in XP and Vista. In Windows 7 I get error messages, so it appears that mine is a perfect case for taking the advice of this article. Unfortunately, it is clear to me that I will never ever be smart enough to understand and implement whatever it says.

    Anyone got any advice for mere mortals?
    Monday, October 26, 2009 5:26 PM
  • This article: http://msdn.microsoft.com/en-us/library/ms648774(VS.85).aspx says that DDE uses SendMessage.

    And this article: http://msdn.microsoft.com/en-us/library/ms644950(VS.85).aspx says that User Interface Privilege Isolation (UIPI) may block SendMessage on Vista and later.

    Unfortunately I don't think this answers your question since UAC (which provides UIPI) was part of Vista and probably the same in Windows 7.
    Tuesday, October 27, 2009 6:13 PM
  • I can confirm that DDE definitely works on Windows 7. I just tested it myself by using a little test DDClient C++ application against Excel 2003 on Windows 7, and it works fine. And it requires no administration privilege itself or for Excel either! YES

    (We are having issues with COM on Windows Vista and 7 such as objects not appearing in the ROT and GetObject not working unless run with admin privilege, and not being able to cope with multiple instances, etc. Since very little communication is involved, I am just going to use DDE.)
    • Proposed as answer by Ben_userdn Friday, November 13, 2009 6:54 PM
    Friday, November 13, 2009 6:53 PM