The listener in the Adapter for OPC represents a subscription. When an OPC Adapter listener is created, a subscription Object gets created in the OPC UA server address space. To subscribe to a node for data change or get events from any event source you must create an OPC Adapter listener notification and add appropriate nodes.

Using an Adapter for OPC connection, an Adapter for OPC listener waits to receive a message from OPC UA server. When a message or event appears for a node that the listener is subscribed to, OPC UA server pushes the message to the listener. The listener then passes the message to a listener notification.

You must never invoke a listener directly from a service or client. Instead, use the Integration Server Administrator to configure, enable, and disable the services.

All listeners function in the following manner: