A UAP in Message Queuing mode communicates by putting and getting elements of a data storing queue (message queue). Like electronic mail, data can be sent and received even if the remote system's application program is not running.

Use the API called Message Queue Interface (MQI) from a UAP to use Message Queuing.

OpenTP1 nodes which use Message Queuing must have TP1/Message Queue. For the usage of Message Queuing, see the OpenTP1 TP1/Message Queue User's Guide.

The figure below shows UAPs using Message Queuing.

Figure 1-4 Outline of UAPs using Message Queuing