Normally, an OpenEdge client application automatically acknowledges a message when the message handler procedure completes. In SINGLE_MESSAGE_ACKNOWLEDGE mode, however, each message requires its own acknowledgement; if you choose not to acknowledge a message, it is never acknowledged.

To turn on SINGLE_MESSAGE_ACKNOWLEDGE mode, an OpenEdge client application calls the setSingleMessageAcknowledgement procedure of the session handle with the input parameter set to TRUE. To turn off this mode, the application calls the same method with the input parameter set to FALSE.