Opc.Ua.Client.Session.ReadValue C# (CSharp) Method

        public DataValue ReadValue(NodeId nodeId)
        {
            ReadValueId itemToRead = new ReadValueId();

            itemToRead.NodeId      = nodeId;
            itemToRead.AttributeId = Attributes.Value;

            ReadValueIdCollection itemsToRead = new ReadValueIdCollection();
            itemsToRead.Add(itemToRead);

            // read from server.
            DataValueCollection values = null;
            DiagnosticInfoCollection diagnosticInfos = null;

            ResponseHeader responseHeader = Read(
                null,
                0,
                TimestampsToReturn.Both,
                itemsToRead,
                out values, 
                out diagnosticInfos);
            
            ClientBase.ValidateResponse(values, itemsToRead);
            ClientBase.ValidateDiagnosticInfos(diagnosticInfos, itemsToRead);
            
            if (StatusCode.IsBad(values[0].StatusCode))
            {
                ServiceResult result = ClientBase.GetResult(values[0].StatusCode, 0, diagnosticInfos, responseHeader);
                throw new ServiceResultException(result);
            }

            return values[0];
        }

        /// <summary>
        /// Updates the application after connecting to or disconnecting from the server.
        /// </summary>
        private void Server_ConnectComplete(object sender, EventArgs e)
        {
            try
            {
                m_session = ConnectServerCTRL.Session;

                if (m_session == null)
                {
                    return;
                }

                // set a suitable initial state.
                if (m_session != null && !m_connectedOnce)
                {
                    m_connectedOnce = true;

                    EventsLV.IsSubscribed = false;
                    EventsLV.DisplayConditions = true;
                    EventsLV.ChangeArea(Opc.Ua.ObjectIds.Server, false);

                    FilterDeclaration filter = new FilterDeclaration();

                    ushort namespaceIndex = (ushort)m_session.NamespaceUris.GetIndex(DsatsDemo.Namespaces.DsatsDemo);

                    filter.EventTypeId = ExpandedNodeId.ToNodeId(DsatsDemo.ObjectTypeIds.LockConditionType, m_session.NamespaceUris);

                    filter.AddSimpleField(String.Empty, BuiltInType.NodeId, false);
                    filter.AddSimpleField(Opc.Ua.BrowseNames.EventId, BuiltInType.ByteString, false);
                    filter.AddSimpleField(Opc.Ua.BrowseNames.EventType, BuiltInType.NodeId, false);
                    filter.AddSimpleField(Opc.Ua.BrowseNames.ConditionName, BuiltInType.String, true);
       
                    filter.AddSimpleField(new QualifiedName[] { 
                        new QualifiedName(DsatsDemo.BrowseNames.LockState, namespaceIndex),
                        new QualifiedName(Opc.Ua.BrowseNames.CurrentState) },
                        BuiltInType.String,
                        ValueRanks.Scalar,
                        true);

                    filter.AddSimpleField(new QualifiedName(DsatsDemo.BrowseNames.ClientUserId, namespaceIndex), BuiltInType.String, true);
                    filter.AddSimpleField(new QualifiedName(DsatsDemo.BrowseNames.SubjectName, namespaceIndex), BuiltInType.String, true);
                    filter.AddSimpleField(new QualifiedName(DsatsDemo.BrowseNames.SessionId, namespaceIndex), BuiltInType.NodeId, true);

                    EventsLV.ChangeFilter(filter, true);
                    
                    m_filter = filter;

                    PhaseCB.Items.Clear();

                    BrowseDescription nodeToBrowse = new BrowseDescription();
                    nodeToBrowse.NodeId = new NodeId(DsatsDemo.Objects.Rig_Phases, namespaceIndex);
                    nodeToBrowse.ReferenceTypeId = Opc.Ua.ReferenceTypeIds.HierarchicalReferences;
                    nodeToBrowse.IncludeSubtypes = true;
                    nodeToBrowse.BrowseDirection = BrowseDirection.Forward;
                    nodeToBrowse.ResultMask = (uint)BrowseResultMask.All;

                    DataValue value = m_session.ReadValue(new NodeId(DsatsDemo.Variables.Rig_CurrentPhase, namespaceIndex));
                    NodeId currentPhase = value.GetValue<NodeId>(null);

                    ReferenceDescriptionCollection references = ClientUtils.Browse(m_session, nodeToBrowse, false);

                    if (references != null)
                    {
                        for (int ii = 0; ii < references.Count; ii++)
                        {
                            PhaseCB.Items.Add(references[ii]);

                            if (currentPhase == references[ii].NodeId)
                            {
                                PhaseCB.SelectedIndex = ii;
                            }
                        }
                    }

                    m_connectedOnce = true;
                }

                EventsLV.IsSubscribed = true;
                EventsLV.ChangeSession(m_session, true);
                EventsLV.ConditionRefresh();
            }
            catch (Exception exception)
            {
                MessageBox.Show(exception.Message, this.Text, MessageBoxButtons.OK, MessageBoxIcon.Error);
            }
        }