Fortunately, i found a way to do it, and it’s working.
This is the solution i used in order to detect “the write action ” from UAExpert in my Java SDK server:

I declared three ‘Variant’ variables: CurrentValue, NewValue, FinalClientValue;

Every 100ms, i compare the Current value to the FinalClientValue (from UAExpert)
if it’s equal, then i update both of them with the NewValue obtained from the MonitoredItem (from Prosys Simulation OPC UA Server)
else : I put the FinalClientValue in the CurrentValue and write it to the Prosys Simulation OPC UA Server.

Question:
Is there a native way, to detect user write action on the node value (client side) in server Java SDK?

Thank you,
Best Regards

Hi Mr Tahvanainen,
sorry for my late reply.

I followed the example of ” Sample Console Client” provided in the SDK, (created subscription, monitored item and a data change Listener), and writing to (MyJavaUAServer) in the “OnDataChange” of the datachange listener

I write the value of the source node from (Prosys OPC UA Simulation Server) to the target node in (MyJavaUAServer) when the data changes as following:

@Override
public void onDataChange(MonitoredDataItem sender, DataValue prevValue, DataValue value) {

TargetNodeId = MyServer.TargetNode(MyServer.Clients.MSClient, sender.getNodeId());

if (value.getValue().getValue() != null)
{
try {
MyServer.Clients.MSClient.writeAttribute(TargetNodeId, Attributes.Value, value.getValue().getValue());
//MSClient: is writing to (MyJavaUAServer)
}
catch (ServiceException | StatusException e)
{
e.printStackTrace();
}
}
}

I deleted the three variables used before, and created a “reverse sens” subscription as you suggested.

Its sending me back notifications on data changes of the source. Is there a way to know what is the client who made the last data change on the monitored item, so i can avoid this.

thank you in advance,
Best regards

Thank you Mr Jouni for your kind support, I have eliminated the return back of data change notifications, by adding a condition in the listener “MyMonitoredDataItemListener”
by comparing the “sender” current value to the current value of the node i want to write to it.

public void onDataChange(MonitoredDataItem sender, DataValue prevValue, DataValue value) {

TargetNodeId = MyServer.TargetNode(sender.getSubscription().getClient(), sender.getNodeId());

try {
TargetNodeCurrentValue = MyServer.Clients.MSClient.readAttribute(TargetNodeId, Attributes.Value);

} catch (ServiceException | StatusException e1) {
e1.printStackTrace();
}

if (value.getValue().getValue() != TargetNodeCurrentValue.getValue().getValue())
{

if (value.getValue().getValue() != null)
{
try
{
this.client.MSClient.writeAttribute(TargetNodeId, Attributes.Value, value.getValue().getValue());
}
catch (ServiceException | StatusException e)
{
e.printStackTrace();
}
}
else System.out.println(“The value is null!”);

}

}

And done the Same thing in the listener in the other side.

Thank you,
Best Regards