Network DDE Application Will Not Connect Via Network DDE

ID: Q169896

The information in this article applies to:

Microsoft Windows NT Workstation versions 3.5, 3.51, 4.0
Microsoft Windows NT Server versions 3.5, 3.51, 4.0
Microsoft Windows for Workgroups version 3.11
Microsoft Windows 95

SYMPTOMS

When a client application uses Network DDE to connect to a remote DDE server application, the connection appears successful. However, the applications cannot communicate through DDE and you may receive the following error message:

DDE Method invoked with no channel.

CAUSE

When establishing a DDE conversation to a remote DDE server (source) using Network DDE, it is important that two operations are performed correctly. You may experience the symptoms listed above if the following two operations are not correctly performed:

The DDESHARE must be created correctly on the DDE server computer using the Windows NT utility, Ddeshare.exe.

The DDE client application must be written to correctly attempt a conversation to the remote Network DDE share.

MORE INFORMATION

DDESHARE

For more information on creating DDE Shares, please see the following article in the Microsoft Knowledge Base:

Q114089 Using the Windows NT NetDDE Share Manager

The information below assumes that a Share has been configured for the Sales.xls spreadsheet in Excel 97 and is based on the following article in the Microsoft Knowledge Base:

Q128491 Creating a NetDDE Link in Excel on Windows NT


   Sharename:  SalesData$
   Application Name:
      Old Style:  Excel
      New Style:  Excel.Sheet.5
      Static:     Excel

   Topic Name:

      Old Style:  [SALES.XLS]Sheet1
      New Style:  SALES.XLS
      Static:     SALES.XLS

   [x]   Allow start application
   [x]   is service

The different styles listed reflect the different types of client applications that may attempt to connect to the server (and the different forms of DDE that they may use). For example, a DDE client that uses DDEML (DDE Management Library), such as Excel 97, accesses the DDE server through the share information listed in the New Style setting.

Connecting Locally

A DDE client requires an application name and topic name in order to connect to a DDE server. When the DDE server and client are on the same computer, and Network DDE is NOT being used, the client attempts to connect to the server using something similar to the following:

Using the Old Style (Message Based DDE) you would use these values:


      Application:  EXCEL
      Topic:        [SALES.XLS]Sheet1

Using the New Style (DDE Management Library (DDEML) based) you would use these values (for Excel 97):



      Application:  Excel.Sheet.8
      Topic:        SALES.XLS

Performing a DDE Request for Item: R1C1 returns the value in Row 1 Column 1 on Sheet 1 of the Sales.xls spreadsheet in both of these examples.

Connecting Through Network DDE

When the DDE server and client are on different computers, and Network DDE is used to connect them, the client attempts to connect to the server using the following rules.

Old Style clients that employ DDE using low-level DDE messaging directly access the network DDE server with a TOPIC name that has the .dde extension appended to the sharename defined by Ddeshare.exe on the DDE server:
```
      Application:  \\SERVERNAME\NDDE$
      Topic:        SALESDATA$.DDE 
```

New Style clients that employ the DDE Management Library (DDEML) access the network DDE server with a TOPIC name that has the .OLE extension appended to the sharename defined by Ddeshare.exe on the DDE server:
```
      Application:  \\SERVERNAME\NDDE$
      Topic:        SALESDATA$.OLE 
```

Static Style clients (applications using Static DDE links) access the network DDE server with a TOPIC name that matches the sharename defined by Ddeshare.exe on the DDE server:
```
      Application:  \\SERVERNAME\NDDE$
      Topic:        SALESDATA$ 
```

Performing a DDE Request for Item: R1C1 returns the value in Row 1 Column 1 on Sheet 1 of the Sales.xls spreadsheet for all of these client types.

The true Application and Topic names that are necessary to connect to the application are not required by the DDE client, but must be correctly configured with DDESHARE on the server. It is also important to ensure that your client is using the appropriate Topic name (with the correct extension) for the entries defined by DDESHARE.

Additional query words: networking

Keywords : kbnetwork wfwg NTSrvWkst
Version : WINDOWS:3.11,95; winnt:3.5,3.51,4.0
Platform : WINDOWS winnt
Issue type : kbhowto