B. Visual Basic as DDE Client
1. Link Topic Property
For a destination control - returns or sets the source application and the topic ( the fundamental data grouping used in the application ) . Use Link Topic with the Link Item property to specify the complete data link.
For a source form - returns or sets the topic that the source form responds to in a DDE conversation.
- Syntax: object. LinkTopic [value]
To activate the data link set within Link Topic, set the Link Mode property to the appropriate non zero value to specify the type of link you want. As a rule, set the Link Mode after you set Link Topic. For a destination control, changing the Link Topic breaks as existing link and terminates the DDE conversation. For a source form changing the Link Topic breaks all destination links that are using that topic. For these reasons, always set the Link Topic for a destination control, you must set LinkMode to 1 ( Automatic ) , 2 (Manual ) , or 3 ( Notify) to establish a connection .
2. Link Item Property
Returns or sets the data passed to a destination control in a DDE conversation with another application.
Use LinkItem in a combination with the Link Topic property to specify the complete
data link for a destination control to a source application . TO activate this link, set the LinkMode property. You set the LinkItem property only for a control used as a destination. Setting a permanent link at design time with the Paste Link command from the Edit menu also sets the LinkMode, LinkTopic, and LinkItem properties. This creates a link that is saved with the form. Each time the form is loaded, Visual Basic attempts to re- establish the conversation.