This exchange of messages is called a conversation . Conversations are about a topic . Think of a topic as the fundamental data grouping used in an application. A workbook in Excel or a form in VB for instance. Topics can be about a specific item , say a particular Excel spreadsheet cell.
Lets look at an example of sending data to a cell in Excel.
This is accomplished with a call to the DdeInitialize API when you click the Initialize button. Next we need to describe our conversation. After these values are entered into the corresponding textboxes the Poke button can be pressed. This uses the DdeCreateStringHandle function to convert our conversation parameters into memory handles. A call to DdeConnect establishes a conversation with a server application that supports the specified service name and topic and returns a handle to the conversation.