| Allegro CL version 8.2 Unrevised from 8.1 to 8.2. 8.1 version |
This document contains the following sections:
1.0 DDE IntroductionDDE stands for Dynamic Data Exchange. Quoting from the Windows API Bible (a standard reference for programming with Windows): "Dynamic Data Exchange is a message protocol that allows Windows applications to exchange data."
Here we briefly describe the functionality available in Lisp for DDE. Note that we do not describe DDE in much detail. We assume you are familiar with using DDE between Windows applications. If you are not, please refer to standard Windows programming manuals. Here are some principles of using DDE in Lisp:
DDE functionality is not part the common-graphics package or inculded
in the :common-graphics
module. Its functionality
is in the dde package in a module named
:dde
. It is not necessary to load Common Graphics
to use DDE functionality. DDE functionality is only available on
Windows.
Evaluating the form
(require :dde)
will cause the DDE module to be loaded if it is not already
present. It is not an error to evaluate this form when the DDE module
is already loaded (the form will return nil
in that case).
There is a simple example illustrating the DDE functionality in examples\cg\dde-examples.cl.
Create a client-port instance by calling make-instance on the client-port
class. Available
initargs are:
These attributes can be changed after the instance is created using setf and the accessors port-name, port-application, and port-topic (all are setf'able). The new values will be used if the port is closed and re-opened.
;; Create a port with the program manager acting as the DDE ;; server (setq port1 (make-instance 'client-port :application :progman :topic :progman))
Any single DDE port (either a client or server port) will work only within a single thread during the time that it is open, and so all of the application code that uses a particular DDE port should run only in one thread. (A port could be opened and closed in one thread and then later opened and closed in another, but it would likely be tricky to ensure that the threads do not have the port open at the same time.)
When a DDE port is opened in a thread, a dde-info
instance is created for
that thread. The function dde-info applied to the process
associated with a thread returns that instance, which can be used as
the argument to various generic functions which provide information
about the port.
The generic function can be used to poll and set values in a dde-info
instance.
Separate DDE ports work in separate threads. Allegro CL will continue to automatically initialize DDE as needed whenever a first port is opened, though now this is handled separately in each thread that begins to use DDE.
*case-sensitive-dde*
for its
default)
dde-info
(the
class)
*generate-dde-messages*
*service-name*
for its
default)
*service-topics*
for its default)
*sysitems*
for its default)
The Windows API offers the function DdeClientTransaction, where the sixth argument is a constant that indicates the type of transaction. For those who are familiar with the Windows DDE API, here is the mapping from those transaction types to the corresponding client functions in Allegro's DDE facility.
:cold
link
:warm
or
:hot
link
Similarly, a DDE server callback function receives transactions of these same types. Here is the mapping from these types to the corresponding generic functions on which methods may be written to implement a DDE server in Allegro.
Copyright (c) 1998-2016, Franz Inc. Oakland, CA., USA. All rights reserved.
This page was not revised from the 8.1 page.
Created 2010.1.21.
| Allegro CL version 8.2 Unrevised from 8.1 to 8.2. 8.1 version |