Once a DDE conversation has begun, the client can establish one or more permanent data links with the server. A data link is a communications mechanism by which the server notifies the client whenever the value of a given data item changes. The data link is permanent in the sense that this notification process continues until the data link or the DDE conversation itself is terminated.
There are two kinds of permanent DDE data links: warm and hot. In a warm data link, the server notifies the client that the value of the data item has changed, but the server does not send the data value to the client until the client requests it. In a hot data link, the server immediately sends the changed data value to the client.
Applications that support warm or hot data links typically provide a Copy or Paste Link command in their Edit menu to enable the user to establish links between applications. For more information, see Initiating a Data Link.