The dialog layer is designed to provide application programmers with a network-protocol-independent API to communications.

This layer provides a network protocol independent API by providing implementations of Dialog classes. A dialog is an implementation of a "pattern of message exchange" between two programs. A common type of dialog, implemented by all communication protocols provided by VA Smalltalk / VAST Platform, is the simple dialog. In a simple dialog, the initiator of the dialog sends a single message to a remote program. The dialog returns the remote program response message or an error if the program cannot be reached. The details of how the remote program is located, how the initial data message is communicated to the remote program, and how the response is received are hidden in the implementation of the dialog.

It is important to understand that although the interface to a dialog class is independent of the network protocol being used, the implementation of the dialog is still specific to the underlying network protocol.