Microsoft KB Archive/169896

= Network DDE Application Will Not Connect Via Network DDE =

Article ID: 169896

Article Last Modified on 12/8/2003

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APPLIES TO


 * Microsoft Windows NT Workstation 3.5
 * Microsoft Windows NT Workstation 3.51
 * Microsoft Windows NT Workstation 4.0 Developer Edition
 * Microsoft Windows NT Server 3.5
 * Microsoft Windows NT Server 3.51
 * Microsoft Windows NT Server 4.0 Standard Edition
 * Microsoft Windows for Workgroups 3.11
 * Microsoft Windows 95

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This article was previously published under Q169896



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:
 * 1) The DDESHARE must be created correctly on the DDE server computer using the Windows NT utility, Ddeshare.exe.
 * 2) The DDE client application must be written to correctly attempt a conversation to the remote Network DDE share.



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

114089 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:

128491 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$ </li></ul>

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: kbhowto kbnetwork KB169896

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