Improve ResendData server support (#1854)

* add resend data support to sample node manager
* After WG discussion, ensure after ResendData only a single value per monitored item is sent in the next publish (sync client cache)
* Seperate resend data state from ready to publish with IsResendData property

Applications/Quickstarts.Servers/SampleNodeManager/DataChangeMonitoredItem.cs

@@ -29,6 +29,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Text;
 using Opc.Ua.Server;
 
 namespace Opc.Ua.Sample
@@ -68,6 +69,7 @@ public DataChangeMonitoredItem(
             m_nextSampleTime = DateTime.UtcNow.Ticks;
             m_readyToPublish = false;
             m_readyToTrigger = false;
+            m_resendData = false;
             m_alwaysReportUpdates = alwaysReportUpdates;
         }
 
@@ -104,6 +106,7 @@ public DataChangeMonitoredItem(
             m_nextSampleTime = DateTime.UtcNow.Ticks;
             m_readyToPublish = false;
             m_readyToTrigger = false;
+            m_resendData = false;
             m_queue = null;
             m_filter = filter;
             m_range = 0;
@@ -465,11 +468,18 @@ public bool IsReadyToTrigger
             }
         }
 
-        public void SetupResendDataTrigger()
+        /// <inheritdoc/>
+        public bool IsResendData
         {
-            // Does nothing since this type of Monitored Item does not support Resend data functionality
+            get
+            {
+                lock (m_lock)
+                {
+                    return m_resendData;
+                }
+            }
         }
-        
+
         /// <summary>
         /// Returns the results for the create request.
         /// </summary>
@@ -516,28 +526,36 @@ public ServiceResult GetModifyResult(out MonitoredItemModifyResult result)
                 return ServiceResult.Good;
             }
         }
+
+        /// <inheritdoc/>
+        public void SetupResendDataTrigger()
+        {
+            lock (m_lock)
+            {
+                if (m_monitoringMode == MonitoringMode.Reporting)
+                {
+                    m_resendData = true;
+                }
+            }
+        }
         #endregion
 
         #region IDataChangeMonitoredItem Members
-        /// <summary>
-        /// Queues a new data change.
-        /// </summary>
+        /// <inheritdoc/>
         public void QueueValue(DataValue value, ServiceResult error)
         {
             QueueValue(value, error, false);
         }
         #endregion
 
         #region IDataChangeMonitoredItem2 Members
-        /// <summary>
-        /// Queues a new data change.
-        /// </summary>
+        /// <inheritdoc/>
         public void QueueValue(DataValue value, ServiceResult error, bool ignoreFilters)
         {
             lock (m_lock)
             {
                 // check if value has changed.
-                if (!m_alwaysReportUpdates)
+                if (!m_alwaysReportUpdates && !ignoreFilters)
                 {
                     if (!Opc.Ua.Server.MonitoredItem.ValueChanged(value, error, m_lastValue, m_lastError, m_filter, m_range))
                     {
@@ -686,31 +704,45 @@ public bool Publish(OperationContext context, Queue<MonitoredItemNotification> n
                 // check if not ready to publish.
                 if (!IsReadyToPublish)
                 {
-                    return false;
+                    if (!m_resendData)
+                    {
+                        return false;
+                    }
+                }
+                else
+                {
+                    // update sample time.
+                    IncrementSampleTime();
                 }
 
-                // update sample time.
-                IncrementSampleTime();
-
                 // update publish flag.
                 m_readyToPublish = false;
                 m_readyToTrigger = false;
 
                 // check if queuing is enabled.
-                if (m_queue == null)
-                {
-                    Publish(context, m_lastValue, m_lastError, notifications, diagnostics);
-                }
-                else
+                if (m_queue != null && (!m_resendData || m_queue.ItemsInQueue != 0))
                 {
                     DataValue value = null;
                     ServiceResult error = null;
 
                     while (m_queue.Publish(out value, out error))
                     {
                         Publish(context, value, error, notifications, diagnostics);
+
+                        if (m_resendData)
+                        {
+                            m_readyToPublish = m_queue.ItemsInQueue > 0;
+                            break;
+                        }
                     }
                 }
+                else
+                {
+                    Publish(context, m_lastValue, m_lastError, notifications, diagnostics);
+                }
+
+                // update flags
+                m_resendData = false;
 
                 return true;
             }
@@ -828,6 +860,7 @@ private void Publish(
         private bool m_alwaysReportUpdates;
         private bool m_semanticsChanged;
         private bool m_structureChanged;
+        private bool m_resendData;
         #endregion
     }
 }

Applications/Quickstarts.Servers/SampleNodeManager/SampleNodeManager.cs

@@ -2970,7 +2970,6 @@ public virtual void TransferMonitoredItems(
                     {
                         monitoredItems[ii].SetupResendDataTrigger();
                     }
-
                     errors[ii] = StatusCodes.Good;
                 }
             }
@@ -2989,10 +2988,9 @@ protected virtual void OnMonitoredItemsTransferred(
             IList<IMonitoredItem> monitoredItems
             )
         {
-            // does nothing.
+            // overridden by the sub-class.
         }
 
-
         /// <summary>
         /// Changes the monitoring mode for a set of monitored items.
         /// </summary>

Applications/ServerControls.Net4/ServerForm.cs

@@ -59,7 +59,7 @@ public ServerForm()
         /// <summary>
         /// Creates a form which displays the status for a UA server.
         /// </summary>
-        public ServerForm(StandardServer server, ApplicationConfiguration configuration, bool showCertificateValidationDialog = false)
+        public ServerForm(StandardServer server, ApplicationConfiguration configuration, bool showCertificateValidationDialog = true)
         {
             InitializeComponent();
 

Applications/ServerControls.Net4/UA Server Controls.csproj

@@ -60,18 +60,12 @@
   </PropertyGroup>
   <ItemGroup>
     <Reference Include="System" />
-    <Reference Include="System.Core">
-      <RequiredTargetFramework>3.5</RequiredTargetFramework>
-      <Private>True</Private>
-    </Reference>
     <Reference Include="System.Drawing" />
+    <Reference Include="System.Numerics" />
     <Reference Include="System.Windows.Forms" />
     <Reference Include="System.Xml.Linq">
       <RequiredTargetFramework>3.5</RequiredTargetFramework>
     </Reference>
-    <Reference Include="System.Data.DataSetExtensions">
-      <RequiredTargetFramework>3.5</RequiredTargetFramework>
-    </Reference>
     <Reference Include="System.Data" />
     <Reference Include="System.Xml" />
   </ItemGroup>

Libraries/Opc.Ua.Server/Subscription/IMonitoredItem.cs

@@ -97,7 +97,12 @@ public interface IMonitoredItem
         bool IsReadyToTrigger { get; set; }
 
         /// <summary>
-        /// Setup the resend data trigger by setting the monitor item in ResendData state
+        /// Gets a value indicating whether the monitored item is resending data.
+        /// </summary>
+        bool IsResendData { get; }
+
+        /// <summary>
+        /// Set the resend data trigger flag.
         /// </summary>
         void SetupResendDataTrigger();