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Dynamic Data Exchange
13
Dynamic Data Exchange
This chapter describes the support of dynamic data exchange (DDE) by
TeemTalk.
Introduction
With the adoption of a standard user interface within the Microsoft Windows
environment, personal computer users are becoming accustomed to the formalised
methods by which keystrokes and mouse actions have a common effect, making it
easier for users to become familiar with and switch between a whole range of
unrelated but important applications.
This commonality extends beyond just the “look and feel” of applications. The
ability to share data between totally independent applications must by now be a very
familiar operation to many Windows users. Generally this is achieved by using the
EDIT facilities of an application - either by copying, cutting or pasting portions of
required information. These operations make use of the Windows system
“clipboard”. The clipboard is a temporary repository of information that requires
direct involvement of the user to initiate and complete transfer of text or graphics
data. Such a means of transferring information is completely manual in its operation.
The user issues a command in an application to copy or cut selected data to the
clipboard, then in another application the user issues a command to paste the data
from the clipboard into that application’s workspace.
Dynamic Data Exchange, or DDE, is an altogether more sophisticated means of
sharing data between applications and, as suggested by its name, the ability to make
“on the fly” links between applications becomes a reality. DDE is most appropriate
for data exchanges that do not require ongoing user interaction. Normally an
application provides a method for the user to establish the link between applications
exchanging data. But once that link is established, the data exchanges between
applications with no further user involvement. DDE can be used to implement a
broad range of application features including:
● Linking to real-time data, such as stock market updates, scientific instruments,
or process control.