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NullPointerException when using Subscriptions

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NullPointerException when using Subscriptions

November 30, 2017
14:18, EET

clemens.boehler

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February 2, 2017

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Hi everybody,

I am trying to integrate subscriptions in our application. However, I am getting this NullpointerException with the latest Java SDK 2.3.2-781

Exception in thread “PublishRequestQueue-35cd9b7e-eadc-43f5-9299-e6ea06277fc4-0157011E” java.lang.NullPointerException
at com.prosysopc.ua.server.Session.getDiagnosticsManager(Unknown Source)
at com.prosysopc.ua.server.Session.a(Unknown Source)
at com.prosysopc.ua.server.ServiceHandler.fireRequestResponse(Unknown Source)
at com.prosysopc.ua.server.ServiceHandler.validateResponse(Unknown Source)
at com.prosysopc.ua.server.SubscriptionServiceHandler$b.run(Unknown Source)
at java.lang.Thread.run(Thread.java:662)

Is this bug already known (and hopefully fixed as well Smile ) because the exception occurs quite frequently. I tried different OPC UA servers (Prosys, Siemens PLC and B&R PLC) and I can reproduce it with all of them.

Could you please have a look at it?

Thanks in advance and knd regards,
Clemens

November 30, 2017
15:32, EET

Bjarne Boström

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April 3, 2012

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Hi,

You posted this on our graphical clients forum and asked about SDK, therefore moved to SDK forum.

This is a server side exception, therefore your statement of “I tried different OPC UA servers” does not make sense.

Which client/client SDK did you use and what did you do?

December 11, 2017
11:20, EET

clemens.boehler

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February 2, 2017

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Hi,

I am using the Prosys-OPC-UA-Java-SDK-Client-Server-Binary-2.3.2-781.jar and the Opc.Ua.Stack-1.02.337.18.jar.

After connecting to a server, I create a Subscription object

subscription = new Subscription();
subscription.setPublishingEnabled(true);
subscription.setPublishingInterval(publishingInterval, TimeUnit.MILLISECONDS);
subscription.addNotificationListener(listener);

and add MonitoredDataItems by

MonitoredDataItem dataItem = new MonitoredDataItem(item.getNodeId());
subscription.addItem(dataItem);

Finally, I add the subscription to the client. Before closing the connection to the server, I remove all subscriptions and I think this causes the exception.

December 12, 2017
19:07, EET

Heikki Tahvanainen

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April 17, 2013

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Hi Clemens,

Thank you for the information. Indeed, there’s a possible NPE in Session.getDiagnosticsManager() method in the latest release version. As Bjarne already mentioned, this is a server side exception.

Fortunately, this condition can only happen when the client is already disconnecting, so the error situation isn’t really catastrophic. But anyway, this is something that is important to fix.

We have already fixed this to our development version, but the fix is not officially released yet. I’ll send you a download link to the fixed version by email.

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