PRB: DDEML with Excel Error: Remote Data Not Accessible

• Microsoft Windows Software Development Kit (SDK) versions 3.1
• Microsoft Win32 Application Programming Interface (API) included with:

      - Microsoft Windows NT versions 3.5 and 3.51
      - Microsoft Windows 95 version 4.0
  

SYMPTOMS

When data is linked between a Microsoft Excel spreadsheet and a DDEML server application, with both applications open, the following error message may appear:

   Remote data not accessible; start application <SERVER FILENAME>.EXE?

CAUSE

Excel broadcasts an initiate to all windows, for every service/topic name pair it finds, in an attempt to initiate a conversation with the server application. (This can be easily verified by running DDESPY and watching Excel broadcast its initiates.) If Excel can't get a response, or gets a NACK (negative ACK), Excel attempts to EXEC() a new instance of the server application.

RESOLUTION

A DDEML server application should return TRUE, in response to the XTYP_CONNECT transaction it receives, for every service/topic name pair it supports. Refer to page 518 of the Microsoft Windows Software Development Kit (SDK) version 3.1 "Programmer's Reference, Volume 3: Messages, Structures, and Functions" for more information on the XTYP_CONNECT transaction.

MORE INFORMATION

The DDEML server application responds to Excel's initiate by sending the XTYP_CONNECT transaction to the DDE callback function of each server application, passing the service and topic names to the server.

If the server application fails to return TRUE to the service/topic name it supports, Excel concludes that it is trying to initiate a DDE link to an application that is not available, and brings up the message box above, thus giving the user an option to start the application.