(Windows only)
Opens
a dynamic data exchange (DDE) client conversation for a specified DDE
server application and topic, and associates the new conversation
with an ABL frame. To identify the conversation, the statement returns
an integer as a unique channel number for this conversation.
This
statement is supported only for backward compatibility. Use the Component
Object Model (COM) instead.
Note: Does not apply
to SpeedScript programming.
Syntax
DDE INITIATE ddeid FRAME frame-handle
APPLICATION server-name TOPIC topic-name[ NO-ERROR ]
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-
ddeid-var
- An integer variable or field that receives the channel number
for the newly opened DDE conversation.
- FRAME frame-handle
- Specifies the handle of the frame that owns the conversation, where
frame-handle is a HANDLE expression. A frame can own more than one
conversation. The AVM records the status of the most recent conversation exchange in a
set of DDE frame attributes. These attributes record the status of every dynamic data
exchange, including advise exchanges (exchanges triggered by DDE-NOTIFY events). The DDE
frame attributes include:
-
DDE-ERROR — The DDE error code returned by the most recent exchange
-
DDE-ID — The channel number of the conversation that had the most recent
exchange
-
DDE-ITEM — The name of the data item referenced by the most recent
exchange
-
DDE-NAME — The name of the server application in the most recent
exchange
-
DDE-TOPIC — The name of the topic of the most recent exchange
- APPLICATION server-name
- Specifies the name of the server application for the conversation, where
server-name is a character expression. The value of
server-name must be unique for each DDE server on your system. It
is usually the filename of the server executable without the extension (for example, the
name EXCEL in Microsoft Excel).
- TOPIC topic-name
- Specifies the name of the topic of the conversation, where
topic-name is a character expression. The value of
topic-name identifies a category defined by the server application.
This is usually the name of a file or other container that includes one or more data
items (for example, the name of a worksheet, such as Sheet1 in Microsoft Excel). An ABL
client can only exchange data with server data items included in the topic of an open
conversation.
- NO-ERROR
- By default, if the statement fails to open a conversation, the AVM raises the ERROR
condition and posts the error to the DDE frame DDE-ERROR attribute. If you specify
NO-ERROR, the AVM does not raise the ERROR condition but does post the error to the DDE
frame.
Example
The
following fragment shows a typical use of the DDE INITIATE statement.
It assumes that the Microsoft Excel application is running, and
has created the default Excel worksheet, Sheet1. It then uses the
DDE INITIATE statement to open a conversation with Sheet1 as the
topic. This allows the AVM to exchange data with the cells of the
worksheet. In this example, the fragment assigns column headings
to the top row of the first three columns in the worksheet:
DEFINE VARIABLE Sheet1 AS INTEGER NO-UNDO. /* DDE-ID to worksheet topic */
DEFINE VARIABLE DDEframe AS HANDLE NO-UNDO. /* DDE frame handle */
/* Create DDE frame */
CREATE FRAME DDEframe
ASSIGN visible = TRUE
hidden = TRUE.
. . .
/* Open a DDE conversation with Sheet1 and assign column headings. */
DDE INITIATE Sheet1 FRAME DDEframe APPLICATION "Excel" TOPIC "Sheet1".
DDE SEND Sheet1 SOURCE "Name" ITEM "R1C1".
DDE SEND Sheet1 SOURCE "YTD Sales" ITEM "R1C2".
DDE SEND Sheet1 SOURCE "State" ITEM "R1C3".
. . .
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Notes
- The
specified DDE server application must be running on the Windows
desktop before you can invoke the DDE INITIATE statement.
- You can close a DDE conversation in three ways: use the DDE TERMINATE
statement, leave the scope of the frame that owns the conversation,
or terminate the server application or topic associated with the
application.
- For more information on using the DDE protocol (including DDE frame
attributes) to exchange data with non-ABL applications, see OpenEdge
Development: Programming Interfaces.
