Client and Server Interaction

DDE always occurs between a client application and a server application. The DDE client application initiates the exchange by establishing a conversation with the server to send transactions to the server. A transaction is a request for data or services. The DDE server application responds to transactions by providing data or services to the client. For example, a graphics application might contain a bar graph representing a corporation's quarterly profits, but the data for the bar graph might be contained in a spreadsheet application. To obtain the latest profit figures, the graphics application (the client) could establish a conversation with the spreadsheet application (the server). The graphics application could then send a transaction to the spreadsheet application, requesting the latest profit figures.

A server can have many clients at the same time, and a client can request data from multiple servers. An application can also be both a client and a server. Either the client or the server can terminate the conversation at any time.