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Programming Interfaces
External Program Interfaces : Windows Dynamic Data Exchange : Using the DDE protocol : The course of a DDE conversation
The course of a DDE conversation
All DDE conversations follow a pattern of execution that varies somewhat with the application.
To open and manage a DDE conversation:
1. Select a named frame to use as a conversation endpoint (DDE frame). DDE attributes of this frame maintain the status of each conversation you open with it.
Note: A DDE frame cannot be a dialog box (no VIEW-AS DIALOG-BOX option).
2. Ensure that the DDE server application is running in your Windows environment and that the DDE frame for your application is realized.
3. Open the conversation to the server application, specifying the DDE frame, application, and topic names. A topic is a category defined by the server that includes specific data items or commands that the client can access.
4. If you want to, send commands to the DDE server that define additional topics or otherwise prepare the server to open DDE conversations. (You typically open an initial conversation for the System topic to execute these commands.)
5. Send and receive data values between your OpenEdge client and DDE server using the data items associated with your topic of conversation. You can converse with server data items on demand, or set up links that let your OpenEdge application automatically receive the data when server data items change value.
6. To close a conversation, remove any links established to associated data items and terminate the conversation.