Opc.Ua.Sample.SampleNodeManager.SubscribeToEvents C# (CSharp) Method

        public virtual ServiceResult SubscribeToEvents(
            OperationContext    context, 
            object              sourceId, 
            uint                subscriptionId, 
            IEventMonitoredItem monitoredItem, 
            bool                unsubscribe)
        {
            ServerSystemContext systemContext = m_systemContext.Copy(context);
            IDictionary<NodeId,NodeState> operationCache = new NodeIdDictionary<NodeState>();

            lock (Lock)
            {
                // check for valid handle.
                NodeState source = IsHandleInNamespace(sourceId);

                if (source == null)
                {
                    return StatusCodes.BadNodeIdInvalid;
                }

                // check if the object supports subscritions.
                BaseObjectState instance = sourceId as BaseObjectState;

                if (instance == null || instance.EventNotifier != EventNotifiers.SubscribeToEvents)
                {
                    return StatusCodes.BadNotSupported;
                }

                MonitoredNode monitoredNode = instance.Handle as MonitoredNode;

                // handle unsubscribe.
                if (unsubscribe)
                {
                    if (monitoredNode != null)
                    {
                        monitoredNode.UnsubscribeToEvents(systemContext, monitoredItem);

                        // do any post processing.
                        OnUnsubscribeToEvents(systemContext, monitoredNode, monitoredItem);
                    }

                    return ServiceResult.Good;
                }

                // subscribe to events.
                if (monitoredNode == null)
                {
                    instance.Handle = monitoredNode = new MonitoredNode(m_server, this, source);
                }

                monitoredNode.SubscribeToEvents(systemContext, monitoredItem);

                // do any post processing.
                OnSubscribeToEvents(systemContext, monitoredNode, monitoredItem);

                return ServiceResult.Good;
            }
        }