DDERequest Method

Uses an open dynamic data exchange (DDE) channel to request information from the receiving application, and returns the information as a string.

Security  Dynamic data exchange (DDE) is an older technology that is not secure. If possible, use a more secure alternative to DDE, such as object linking and embedding (OLE).

expression**.DDERequest(Channel**, Item)

expression Optional. An expression that returns an Application object.

Channel    Required Long. The channel number returned by the DDEInitiate method.

Item    Required String. The item to be requested.

Remarks

When you request information from the topic in the server application, you must specify the item in that topic whose contents you're requesting. In Microsoft Excel, for example, cells are valid items, and you refer to them by using either the "R1C1" format or named references.

Microsoft Excel and other applications that support DDE recognize a topic named "System." Three standard items in the System topic are described in the following table. Note that you can get a list of the other items in the System topic by using the SysItems item.

Item in System topic	Effect
SysItems	Returns a list of all the items in the System topic.
Topics	Returns a list of all the available topics.
Formats	Returns a list of all the Clipboard formats supported by Word.

Example

This example opens the Microsoft Excel workbook Book1.xls and retrieves the contents of cell R1C1.

Dim lngChannel As Long

lngChannel = DDEInitiate(App:="Excel", Topic:="System")
DDEExecute Channel:=lngChannel, Command:="[OPEN(" & Chr(34) _
    & "C:\Documents\Book1.xls" & Chr(34) & ")]"
DDETerminate Channel:=lngChannel
lngChannel = DDEInitiate(App:="Excel", Topic:="Book1.xls")
MsgBox DDERequest(Channel:=lngChannel, Item:="R1C1")
DDETerminateAll

This example opens a channel to the System topic in Microsoft Excel and then uses the Topics item to return a list of available topics. The example inserts the topic list, which includes all open workbooks, after the selection.

Dim lngChannel As Long
Dim strTopicList As String

lngChannel = DDEInitiate(App:="Excel", Topic:="System")
strTopicList = DDERequest(Channel:=lngChannel, Item:="Topics")
Selection.InsertAfter strTopicList
DDETerminate Channel:=lngChannel

Applies to | Application Object | Global Object

See Also | Communicating with Other Applications | DDEPoke Method