Overview

The Windows environment provides a high degree of compatibility between applications and, as a result, there are several ways of transferring data between applications. The clipboard has already been described; this is a method by which the user can move data from one application to another. However, it is also possible for the application to communicate with another Windows application and ensure that data is updated automatically. Two methods are described here: Dynamic Data Exchange (DDE) and Object Linking and Embedding (OLE).

Dynamic Data Exchange (DDE)

The DDE methods lets you create a link between your application and any other application with DDE capabilities. It is important to stress that both applications must be programmed for DDE. However, many of the most commonly used applications have DDE built in: for example, Microsoft Excel, Word, and Paint.

The link between the applications is generally referred to as a conversation. Two applications take part in each conversation: The application receiving data is the destination or client and the application sending data is the source or server.

Each conversation needs three types of information:

The application and topic are fixed for any conversation, but once the conversation has started many items of data may be transferred.