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UserDde

UserDde is an interactive application that allow the user to experiment with most all aspects of a Dynamic Data Exchange(DDE) conversation. UserDde enables the user to query from and experiment with the capabilities of any other DDE aware application, including Excel and Winword. In addition, UserDde provides the VB developer with a model after which to pattern other DDE methods, including the receipt of execution commands from a client.

From the client side, the user can invoke a manual(cold), automatic(hot), or notification(warm) link and make individual Requests of the server, Poke data back to the server, or send Execute commands to the server.

As a server, the user can supply UserDde with data with which to update any clients which have links to it and watch as its clients are automatically updated or notified of changes being made to the server database.


Client Features

As a DDE client application, UserDde can establish three modes of linking: Manual, Automatic, and Notification. In order to enable the Manual link, both a server name and topic name must be specified. For the Automatic and Notification links, the server name, topic name, and item name must be specified.

The control acting as the client is the main text window at the bottom of the form. As such, UserDde only has the ability to handle text formatted data.


Link Modes

Manual Link

Automatic Link

Notify Link


Manual LinkMode

When a Manual Link is established, the client can Request items of data, Poke data back to the server, or send the server Execute commands.


Automatic LinkMode

To establish an Automatic link, the user must specify the server, topic, and item name. If accepted by the server, the server will update the client with new data as any changes to its database are made.


Notify LinkMode

To establish an Notification link, the user must specify the server, topic, and item name. If accepted by the server, the server will notify the client when any change to its database is made. UserDde will notify the user that a notification has been received by 1) displaying an appropriate message in its status display window and 2) flashing the status window label. When desired, the user will then Request updated data.


Link Methods

Request Method

Poke Method

Execute Method


Request Method

Many servers can supply data to a client upon request. To Request data, the client must have previously established  either a Manual or Notify link. In addition, an item name must also be specified. Upon making a valid request, the server will pass the data to the client and the data will be displayed in the data window.


Poke Method

Some servers allow the client to pass(poke) to them updated items of data, at which time the server will update its database. To poke data, the user must 1) specify a valid item name and 2) provide the data in the Data Window.


Execute Method

Some servers allow the client to pass a stream of commands for execution at the server. For example, a client application can pass Excel macros to Excel and WordBasic macros to Winword. Another noted server that accepts execute commands it Program Manager, allowing operations as the creation of group windows and the addition of program items to those groups. Note that no item name need be specified to invoke an execute command. In order to enable the Execute option, the user must have a conversation underway and have execution commands specified in the Data window.


Server Features

UserDde, at the user's option, can act as a DDE server. As a server, it has the following attributes:

Property	Name	Description
Server Name:	UserDde
Topic Name:	UserDde
Item Names:	txtData	This is the main display window located at the bottom of the form window.
	Text1(0)	Server name window
	Text1(1)	Topic name window
	Text1(2)	Item name window
	Text1(3)	Timeout window


Miscellaneous Features


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