Event subscription .Net

[benoitdaireaux]

Hello,
I want to subscribe to events notified by a server, and filter those events based on the source nodeid value.
The following piece of code works when I use the UnifiedAutomation SDK:

  //using UA SDK
  EventMonitoredItem eventMonitoredItem = new EventMonitoredItem(ObjectIds.Server);
  eventMonitoredItem.Filter = new ItemEventFilter(Session.NamespaceUris)
  {
      SelectClauses =
      {
          BrowseNames.EventId,
          BrowseNames.EventType,
          BrowseNames.Message,
          BrowseNames.Severity,
          BrowseNames.SourceName,
          BrowseNames.Time
      }
  };

  eventMonitoredItem.Filter.WhereClauses.Add(FilterOperator.Equals, BrowseNames.SourceNode, new Variant(nodeId));

and I would like to reproduce it using the OPCFoundation .net SDK.
I couldn't find a way to properly set the select and where clauses (I suspect the where clause is the main issue).

ChatGPT (openAI) suggests the more or less the following:

  //open AI:
  EventFilter filter = new EventFilter
  {
      SelectClauses = new SimpleAttributeOperand[]
      {
          new SimpleAttributeOperand
          {
              TypeDefinitionId = ObjectTypeIds.BaseEventType,
              BrowsePath = new QualifiedName[] { BrowseNames.SourceName }
          }
      },
      WhereClause = new ContentFilter()
  };

  filter.WhereClause.Push(FilterOperator.Equals, new SimpleAttributeOperand
  {
      TypeDefinitionId = ObjectTypeIds.BaseEventType,
      BrowsePath = new QualifiedName[] { BrowseNames.SourceNode }
  }, new Variant(nodeId));

but this doesn't work.
Any assistance or tips would be appreciated!

Thanks,
Benoît Daireaux

[SvenEV-bakerhughes]

Wouldn't something like this work, pretty much equivalent to the UA SDK?

filter.WhereClause.Push(FilterOperator.Equals, BrowseNames.SourceNode, new Variant(nodeId));

It would also be helpful if you could specify what exactly isn't working. Do you get a compiler error? All events, regardless of SourceNode? Or no events at all?

[benoitdaireaux]

Hello, thanks a lot for your comment. I am pretty sure your suggestion is correct, however I still don't get it right.
In fact, I don't don't get any event at all, even when clearing all the filters so my error is certainly elsewhere, in the subscription or monitored item.
Below is the code for the subscription

Opc.Ua.Client.Subscription subscription = new Opc.Ua.Client.Subscription(_session.DefaultSubscription) { PublishingEnabled = true, PublishingInterval = 100 };

_session.AddSubscription(subscription);

EventFilter filter = new EventFilter();
filter.AddSelectClause(ObjectTypes.BaseEventType, Opc.Ua.BrowseNames.EventId);
filter.AddSelectClause(ObjectTypes.BaseEventType, Opc.Ua.BrowseNames.EventType);
filter.AddSelectClause(ObjectTypes.BaseEventType, Opc.Ua.BrowseNames.SourceNode);
filter.AddSelectClause(ObjectTypes.BaseEventType, Opc.Ua.BrowseNames.SourceName);
filter.AddSelectClause(ObjectTypes.BaseEventType, Opc.Ua.BrowseNames.Time);
//filter.AddSelectClause(ObjectTypes.BaseEventType, Opc.Ua.BrowseNames.ReceiveTime);
//filter.AddSelectClause(ObjectTypes.BaseEventType, Opc.Ua.BrowseNames.LocalTime);
filter.AddSelectClause(ObjectTypes.BaseEventType, Opc.Ua.BrowseNames.Message);
filter.AddSelectClause(ObjectTypes.BaseEventType, Opc.Ua.BrowseNames.Severity);

filter.WhereClause.Push(FilterOperator.Equals, BrowseNames.SourceNode, new Variant(nodeId));

var monitoredItem = new Opc.Ua.Client.MonitoredItem(subscription.DefaultItem)
{
    NodeClass = NodeClass.Object, 
    StartNodeId = Opc.Ua.ObjectIds.Server,
    //AttributeId = Opc.Ua.Attributes.EventNotifier,
    DisplayName = $"EventNotifier for node \"{nodeId}\"",
    MonitoringMode = Opc.Ua.MonitoringMode.Reporting,
    SamplingInterval = 0,
    QueueSize = 0,
    DiscardOldest = true,
    Filter = filter ,
                    
};
monitoredItem.Notification += MonitoredItem_Notification1;                    

subscription.AddItem(monitoredItem);

subscription.Create();