Hello,

What do you mean when you say that a Subscription or a MonitoredItem “has gone bad”?

To get a list of all Subscriptions, you can call client.getSubscription() where client is an instance of UaClient class. To get all MonitoredItems of a Subscription, you can call subscription.getItems() where subscription is instance of Subscription class. The MonitoredItems are returned in MonitoredItemBase form which you can cast to MonitoredItem form to read their error code swith item.getErrorCode() where item is an instance of MonitoredItem class.

You can also use the onDataChange method of MonitoredDataItemListener interface to perform an action when the StatusCode of a received DataValue is Bad for a MonitoredDataItem.

Hello,

You could probably use SubscriptionAliveListener interface to monitor whether or not a Subscription is alive or not. Particularly onTimeout and onLifetimeTimeout are triggered for different types of timeouts and onAlive is triggered when receiving alive messages from the Server.

MonitoredItems themselves don’t have a concept of being alive or not in the OPC UA Specification. Or in other words, the specification doesn’t define a type of notification that the Server would send to inform that the MonitoredItem is still alive but its value hasn’t changed. But you can use the previously mentioned MonitoredDataItemListener interface to handle DataValues with Bad StatusCodes.