org.eclipse.milo.opcua.sdk.client.subscriptions

Interface ManagedSubscription.ChangeListener

Enclosing class:

ManagedSubscription

public static interface ManagedSubscription.ChangeListener

A callback that receives data and event change notifications for ManagedDataItems and ManagedEventItems belonging to a ManagedSubscription.

Method Summary

Modifier and Type	Method and Description
default void	onDataReceived(List<ManagedDataItem> dataItems, List<org.eclipse.milo.opcua.stack.core.types.builtin.DataValue> dataValues) New values for dataItems have arrived.
default void	onEventReceived(List<ManagedEventItem> eventItems, List<org.eclipse.milo.opcua.stack.core.types.builtin.Variant[]> eventFields) New events for eventItems have arrived.
default void	onKeepAliveReceived() The keep alive interval for the subscription has expired without any value changes and an empty "keep alive" DataChangeNotification has arrived.

Method Detail

onDataReceived

default void onDataReceived(List<ManagedDataItem> dataItems,
                            List<org.eclipse.milo.opcua.stack.core.types.builtin.DataValue> dataValues)

New values for dataItems have arrived.

Take care not to block unnecessarily in this callback because subscription notifications are processed synchronously as a backpressure mechanism. Blocking inside this callback will prevent subsequent notifications from being processed and new PublishRequests from being sent.

Parameters:

dataItems - the list of ManagedDataItems for which new values have arrived.

dataValues - the corresponding DataValue for each ManagedDataItem in dataItems.

onEventReceived

default void onEventReceived(List<ManagedEventItem> eventItems,
                             List<org.eclipse.milo.opcua.stack.core.types.builtin.Variant[]> eventFields)

New events for eventItems have arrived.

Take care not to block unnecessarily in this callback because subscription notifications are processed synchronously as a backpressure mechanism. Blocking inside this callback will prevent subsequent notifications from being processed and new PublishRequests from being sent.

Parameters:

eventItems - the list of ManagedEventItem for which new events have arrived.

eventFields - the corresponding event field values for each ManagedEventItem in eventItems.

onKeepAliveReceived

default void onKeepAliveReceived()

The keep alive interval for the subscription has expired without any value changes and an empty "keep alive" DataChangeNotification has arrived. No action is required.