Dynamic Data Exchange from the User's Point of View

The following example illustrates illustrates how two DDE applications can cooperate, as seen from the user's point of view.

A spreadsheet user wants to use Microsoft® Excel to track the price of a particular stock on the New York Stock Exchange. The user has a Win32-based application called Quote that in turn has access to NYSE data. The DDE conversation between Microsoft Excel and Quote takes place as follows:

• The user initiates the conversation by supplying the name of the application (Quote) that will supply the data and the particular topic of interest (NYSE). The resulting DDE conversation is used to request quotes on specific stocks.
• Microsoft Excel broadcasts the application and topic names to all DDE applications currently running in the system. Quote responds, establishing a conversation with Microsoft Excel about the NYSE topic.
• The user can then create a spreadsheet formula in a cell that requests that the spreadsheet be automatically updated whenever a particular stock quotation changes. For example, the user could request an automatic update whenever a change occurs in the selling price of ZAXX stock by specifying the following Microsoft Excel formula:

  ='Quote'|'NYSE'!ZAXX 
   

• The user can terminate the automatic updating of the ZAXX stock quotation at any time. Other data links that were established separately (such as for quotations for other stocks) still will remain active under the same NYSE conversation.
• The user can also terminate the entire conversation between Microsoft Excel and Quote on the NYSE topic, so that no specific data links on that topic can be established without initiating a new conversation.