Fixed #2: Improve connection status and changing servers

PettingZoo.Core/Connection/ConnectionParams.cs

@@ -17,5 +17,11 @@
             Username = username;
             Password = password;
         }
+
+
+        public override string ToString()
+        {
+            return $"{Host}:{Port}{VirtualHost}";
+        }
     }
 }

PettingZoo.Core/Connection/DynamicConnection.cs

@@ -0,0 +1,100 @@
+using System;
+using System.Diagnostics.CodeAnalysis;
+using System.Threading.Tasks;
+
+namespace PettingZoo.Core.Connection
+{
+    public class DynamicConnection : IConnection
+    {
+        public Guid ConnectionId => currentConnection?.ConnectionId ?? Guid.Empty;
+        public ConnectionParams? ConnectionParams { get; private set; }
+        public ConnectionStatus Status { get; private set; } = ConnectionStatus.Disconnected;
+        public event EventHandler<StatusChangedEventArgs>? StatusChanged;
+
+
+        private IConnection? currentConnection;
+
+
+        public async ValueTask DisposeAsync()
+        {
+            if (currentConnection != null)
+                await currentConnection.DisposeAsync();
+
+            GC.SuppressFinalize(this);
+        }
+
+
+        public void Connect()
+        {
+            CheckConnection();
+            currentConnection.Connect();
+
+        }
+
+        public async ValueTask Disconnect()
+        {
+            if (currentConnection == null)
+                return;
+
+            var disconnectedConnectionId = currentConnection.ConnectionId;
+            await currentConnection.DisposeAsync();
+            currentConnection = null;
+
+            ConnectionStatusChanged(this, new StatusChangedEventArgs(disconnectedConnectionId, ConnectionStatus.Disconnected));
+        }
+
+
+        public void SetConnection(IConnection connection)
+        {
+            if (currentConnection != null)
+            {
+                currentConnection.StatusChanged -= ConnectionStatusChanged;
+                ConnectionStatusChanged(this, new StatusChangedEventArgs(currentConnection.ConnectionId, ConnectionStatus.Disconnected));
+            }
+
+            currentConnection = connection;
+
+            // Assume we get the new connection before Connect is called, thus before the status changes
+            if (currentConnection != null)
+                currentConnection.StatusChanged += ConnectionStatusChanged;
+        }
+
+
+        public ISubscriber Subscribe(string exchange, string routingKey)
+        {
+            CheckConnection();
+            return currentConnection.Subscribe(exchange, routingKey);
+        }
+
+
+        public ISubscriber Subscribe()
+        {
+            CheckConnection();
+            return currentConnection.Subscribe();
+        }
+
+
+        public Task Publish(PublishMessageInfo messageInfo)
+        {
+            CheckConnection();
+            return currentConnection.Publish(messageInfo);
+        }
+
+
+        private void ConnectionStatusChanged(object? sender, StatusChangedEventArgs e)
+        {
+            ConnectionParams = e.ConnectionParams;
+            Status = e.Status;
+
+            StatusChanged?.Invoke(sender, e);
+        }
+
+
+        [MemberNotNull(nameof(currentConnection))]
+        private void CheckConnection()
+        {
+            if (currentConnection == null)
+                throw new InvalidOperationException("No current connection");
+        }
+    }
+}

PettingZoo.Core/Connection/IConnection.cs

@@ -5,8 +5,15 @@ namespace PettingZoo.Core.Connection
 {
     public interface IConnection : IAsyncDisposable
     {
+        Guid ConnectionId { get; }
+        ConnectionParams? ConnectionParams { get; }
+        ConnectionStatus Status { get; }
+
         event EventHandler<StatusChangedEventArgs> StatusChanged;
 
+
+        void Connect();
+
         ISubscriber Subscribe(string exchange, string routingKey);
         ISubscriber Subscribe();
 
@@ -25,14 +32,18 @@ namespace PettingZoo.Core.Connection
 
     public class StatusChangedEventArgs : EventArgs
     {
+        public Guid ConnectionId { get; }
         public ConnectionStatus Status { get; }
-        public string? Context { get; }
+        public ConnectionParams? ConnectionParams { get; }
+        public Exception? Exception { get; }
 
 
-        public StatusChangedEventArgs(ConnectionStatus status, string? context)
+        public StatusChangedEventArgs(Guid connectionId, ConnectionStatus status, ConnectionParams? connectionParams = null, Exception? exception = null)
         {
+            ConnectionId = connectionId;
             Status = status;
-            Context = context;
+            ConnectionParams = connectionParams;
+            Exception = exception;
         }
     }
 }

PettingZoo.RabbitMQ/RabbitMQClientConnection.cs

@@ -3,51 +3,56 @@ using System.Threading;
 using System.Threading.Tasks;
 using PettingZoo.Core.Connection;
 using RabbitMQ.Client;
+using IConnection = RabbitMQ.Client.IConnection;
 
 namespace PettingZoo.RabbitMQ
 {
     public class RabbitMQClientConnection : Core.Connection.IConnection
     {
+        public Guid ConnectionId { get; } = Guid.NewGuid();
+        public ConnectionParams? ConnectionParams { get; }
+        public ConnectionStatus Status { get; set; }
+        public event EventHandler<StatusChangedEventArgs>? StatusChanged;
+
+        
         private const int ConnectRetryDelay = 5000;
 
         private readonly CancellationTokenSource connectionTaskToken = new();
-        private readonly Task connectionTask;
+        private Task? connectionTask;
         private readonly object connectionLock = new();
-        private global::RabbitMQ.Client.IConnection? connection;
+        private IConnection? connection;
-        private IModel? model;
-
-
-        public event EventHandler<StatusChangedEventArgs>? StatusChanged;
 
 
         public RabbitMQClientConnection(ConnectionParams connectionParams)
         {
-            connectionTask = Task.Factory.StartNew(() => TryConnection(connectionParams, connectionTaskToken.Token), CancellationToken.None);
+            ConnectionParams = connectionParams;
         }
 
 
         public async ValueTask DisposeAsync()
         {
+            GC.SuppressFinalize(this);
+            if (connectionTask == null)
+                return;
+
             connectionTaskToken.Cancel();
             if (!connectionTask.IsCompleted)
                 await connectionTask;
 
             lock (connectionLock)
             {
-                if (model != null)
-                {
-                    model.Dispose();
-                    model = null;
-                }
-
                 if (connection != null)
                 {
                     connection.Dispose();
                     connection = null;
                 }
             }
+        }
 
-            GC.SuppressFinalize(this);
+
+        public void Connect()
+        {
+            connectionTask = Task.Factory.StartNew(() => TryConnection(ConnectionParams!, connectionTaskToken.Token), CancellationToken.None);
         }
 
 
@@ -67,6 +72,7 @@ namespace PettingZoo.RabbitMQ
         {
             lock (connectionLock)
             {
+                var model = connection?.CreateModel();
                 var subscriber = new RabbitMQClientSubscriber(model, exchange, routingKey);
                 if (model != null)
                     return subscriber;
@@ -79,10 +85,10 @@ namespace PettingZoo.RabbitMQ
 
                     lock (connectionLock)
                     {
-                        if (model == null)
+                        if (connection == null)
                             return;
 
-                        subscriber.Connected(model);
+                        subscriber.Connected(connection.CreateModel());
                     }
 
                     StatusChanged -= ConnectSubscriber;
@@ -97,12 +103,30 @@ namespace PettingZoo.RabbitMQ
 
         public Task Publish(PublishMessageInfo messageInfo)
         {
-            if (model == null)
+            IConnection? lockedConnection;
+
+            lock (connectionLock)
+            {
+                lockedConnection = connection;
+            }
+
+            if (lockedConnection == null)
                 throw new InvalidOperationException("Not connected");
 
-            model.BasicPublish(messageInfo.Exchange, messageInfo.RoutingKey, false,
+            using (var model = lockedConnection.CreateModel())
-                RabbitMQClientPropertiesConverter.Convert(messageInfo.Properties, model.CreateBasicProperties()),
+            {
-                messageInfo.Body);
+                try
+                {
+                    model.BasicPublish(messageInfo.Exchange, messageInfo.RoutingKey, false,
+                        RabbitMQClientPropertiesConverter.Convert(messageInfo.Properties,
+                            model.CreateBasicProperties()),
+                        messageInfo.Body);
+                }
+                finally
+                {
+                    model.Close();
+                }
+            }
 
             return Task.CompletedTask;
         }
@@ -119,22 +143,22 @@ namespace PettingZoo.RabbitMQ
                 Password = connectionParams.Password
             };
 
-            var statusContext = $"{connectionParams.Host}:{connectionParams.Port}{connectionParams.VirtualHost}";
-
             while (!cancellationToken.IsCancellationRequested)
             {
-                DoStatusChanged(ConnectionStatus.Connecting, statusContext);
+                DoStatusChanged(ConnectionStatus.Connecting);
                 try
                 {
-                    connection = factory.CreateConnection();
+                    lock (connectionLock)
-                    model = connection.CreateModel();
+                    {
+                        connection = factory.CreateConnection();
+                    }
 
-                    DoStatusChanged(ConnectionStatus.Connected, statusContext);
+                    DoStatusChanged(ConnectionStatus.Connected);
                     break;
                 }
                 catch (Exception e)
                 {
-                    DoStatusChanged(ConnectionStatus.Error, e.Message);
+                    DoStatusChanged(ConnectionStatus.Error, e);
 
                     try
                     {
@@ -148,9 +172,10 @@ namespace PettingZoo.RabbitMQ
         }
 
 
-        private void DoStatusChanged(ConnectionStatus status, string? context = null)
+        private void DoStatusChanged(ConnectionStatus status, Exception? exception = null)
         {
-            StatusChanged?.Invoke(this, new StatusChangedEventArgs(status, context));
+            Status = status;
+            StatusChanged?.Invoke(this, new StatusChangedEventArgs(ConnectionId, status, ConnectionParams, exception));
         }
     }
 }

PettingZoo/UI/Main/MainWindowStrings.Designer.cs

@@ -160,7 +160,7 @@ namespace PettingZoo.UI.Main {
         }
         
         /// <summary>
-        ///   Looks up a localized string similar to Connected.
+        ///   Looks up a localized string similar to Connected to {0}.
         /// </summary>
         public static string StatusConnected {
             get {

PettingZoo/UI/Main/MainWindowStrings.resx

@@ -151,7 +151,7 @@
     <value>Importing messages...</value>
   </data>
   <data name="StatusConnected" xml:space="preserve">
-    <value>Connected</value>
+    <value>Connected to {0}</value>
   </data>
   <data name="StatusConnecting" xml:space="preserve">
     <value>Connecting to {0}...</value>

PettingZoo/UI/Main/MainWindowViewModel.cs

@@ -43,7 +43,7 @@ namespace PettingZoo.UI.Main
         private readonly IExportImportFormatProvider exportImportFormatProvider;
 
         private SubscribeDialogParams? subscribeDialogParams;
-        private IConnection? connection;
+        private readonly DynamicConnection connection = new();
         private string connectionStatus;
         private ITab? activeTab;
         private readonly Dictionary<ITab, Window> undockedTabs = new();
@@ -141,15 +141,15 @@ namespace PettingZoo.UI.Main
             closeTabCommand = new DelegateCommand(CloseTabExecute, HasActiveTabCanExecute);
             undockTabCommand = new DelegateCommand(UndockTabExecute, HasActiveTabCanExecute);
             importCommand = new DelegateCommand(ImportExecute);
+
+            connection.StatusChanged += ConnectionStatusChanged;
         }
 
 
         public async ValueTask DisposeAsync()
         {
             GC.SuppressFinalize(this);
-
+            await connection.DisposeAsync();
-            if (connection != null)
-                await connection.DisposeAsync();
         }
 
         
@@ -159,13 +159,9 @@ namespace PettingZoo.UI.Main
             if (connectionSettings == null)
                 return;
 
-            if (connection != null)
+            connection.SetConnection(connectionFactory.CreateConnection(new ConnectionParams(
-                await connection.DisposeAsync();
-
-            connection = connectionFactory.CreateConnection(new ConnectionParams(
                 connectionSettings.Host, connectionSettings.VirtualHost, connectionSettings.Port,
-                connectionSettings.Username, connectionSettings.Password));
+                connectionSettings.Username, connectionSettings.Password)));
-            connection.StatusChanged += ConnectionStatusChanged;
 
             if (connectionSettings.Subscribe)
             {
@@ -173,38 +169,20 @@ namespace PettingZoo.UI.Main
                 tabFactory.CreateSubscriberTab(connection, subscriber);
             }
 
+            connection.Connect();
             ConnectionChanged();
         }
 
 
         private async void DisconnectExecute()
         {
-            Tabs.Clear();
+            await connection.Disconnect();
-
-            var capturedUndockedTabs = undockedTabs.ToList();
-            undockedTabs.Clear();
-
-            foreach (var undockedTab in capturedUndockedTabs)
-                undockedTab.Value.Close();
-
-            RaisePropertyChanged(nameof(NoTabsVisibility));
-            undockTabCommand.RaiseCanExecuteChanged();
-
-            if (connection != null)
-            {
-                await connection.DisposeAsync();
-                connection = null;
-            }
-
-            ConnectionStatus = GetConnectionStatus(null);
-            ConnectionStatusType = ConnectionStatusType.Error;
-            ConnectionChanged();
         }
 
 
         private void SubscribeExecute()
         {
-            if (connection == null)
+            if (connection.Status != Core.Connection.ConnectionStatus.Connected)
                 return;
 
             var newParams = subscribeDialog.Show(subscribeDialogParams);
@@ -220,7 +198,7 @@ namespace PettingZoo.UI.Main
 
         private void PublishExecute()
         {
-            if (connection == null)
+            if (connection.Status != Core.Connection.ConnectionStatus.Connected)
                 return;
 
             tabFactory.CreatePublisherTab(connection);
@@ -229,7 +207,7 @@ namespace PettingZoo.UI.Main
 
         private bool IsConnectedCanExecute()
         {
-            return connection != null;
+            return connection.Status == Core.Connection.ConnectionStatus.Connected;
         }
 
 
@@ -419,6 +397,8 @@ namespace PettingZoo.UI.Main
                 Core.Connection.ConnectionStatus.Connecting => ConnectionStatusType.Connecting,
                 _ => ConnectionStatusType.Error
             };
+
+            Application.Current.Dispatcher.BeginInvoke(ConnectionChanged);
         }
 
 
@@ -427,9 +407,9 @@ namespace PettingZoo.UI.Main
         {
             return args?.Status switch
             {
-                Core.Connection.ConnectionStatus.Connecting => string.Format(MainWindowStrings.StatusConnecting, args.Context),
+                Core.Connection.ConnectionStatus.Connecting => string.Format(MainWindowStrings.StatusConnecting, args.ConnectionParams),
-                Core.Connection.ConnectionStatus.Connected => string.Format(MainWindowStrings.StatusConnected, args.Context),
+                Core.Connection.ConnectionStatus.Connected => string.Format(MainWindowStrings.StatusConnected, args.ConnectionParams),
-                Core.Connection.ConnectionStatus.Error => string.Format(MainWindowStrings.StatusError, args.Context),
+                Core.Connection.ConnectionStatus.Error => string.Format(MainWindowStrings.StatusError, args.Exception?.Message),
                 Core.Connection.ConnectionStatus.Disconnected => MainWindowStrings.StatusDisconnected,
                 _ => MainWindowStrings.StatusDisconnected
             };

PettingZoo/UI/Tab/ITabFactory.cs

@@ -4,7 +4,7 @@ namespace PettingZoo.UI.Tab
 {
     public interface ITabFactory
     {
-        void CreateSubscriberTab(IConnection? connection, ISubscriber subscriber);
+        void CreateSubscriberTab(IConnection connection, ISubscriber subscriber);
         string CreateReplySubscriberTab(IConnection connection);
         void CreatePublisherTab(IConnection connection, ReceivedMessageInfo? fromReceivedMessage = null);
     }

PettingZoo/UI/Tab/Publisher/PublisherView.xaml

@@ -8,7 +8,7 @@
              xmlns:svgc="http://sharpvectors.codeplex.com/svgc/"
              xmlns:valueConverters="clr-namespace:PettingZoo.WPF.ValueConverters;assembly=PettingZoo.WPF"
              mc:Ignorable="d" 
-             d:DesignHeight="450" 
+             d:DesignHeight="1200" 
              d:DesignWidth="800"
              d:DataContext="{d:DesignInstance res:DesignTimePublisherViewModel, IsDesignTimeCreatable=True}"
              Background="White">
@@ -34,6 +34,7 @@
                     <RowDefinition Height="16" />
                     <RowDefinition Height="Auto" />
                     <RowDefinition Height="Auto" />
+                    <RowDefinition Height="Auto" />
                 </Grid.RowDefinitions>
                 <Grid.ColumnDefinitions>
                     <ColumnDefinition Width="Auto" SharedSizeGroup="Label" />
@@ -81,6 +82,7 @@
                 <ContentControl Grid.Row="10" Grid.Column="0" Grid.ColumnSpan="2" Margin="0 8 0 0" Content="{Binding MessageTypeControl}" />
 
                 <Button Grid.Row="11" Grid.Column="1" Command="{Binding PublishCommand}" Content="{x:Static res:PublisherViewStrings.CommandPublish}" HorizontalAlignment="Left" />
+                <TextBlock Grid.Row="12" Grid.Column="1" Text="{x:Static res:PublisherViewStrings.Published}" Visibility="{Binding PublishedVisibility}" />
             </controls:GridLayout>
         </ScrollViewer>
 

PettingZoo/UI/Tab/Publisher/PublisherViewModel.cs

@@ -8,7 +8,7 @@ using System.Threading.Tasks;
 using System.Windows;
 using System.Windows.Forms;
 using System.Windows.Input;
-using Accessibility;
+using System.Windows.Threading;
 using Newtonsoft.Json;
 using Newtonsoft.Json.Converters;
 using PettingZoo.Core.Connection;
@@ -17,11 +17,12 @@ using PettingZoo.Core.Generator;
 using PettingZoo.Core.Macros;
 using PettingZoo.Core.Settings;
 using PettingZoo.WPF.ViewModel;
+using Application = System.Windows.Application;
 using UserControl = System.Windows.Controls.UserControl;
 
 namespace PettingZoo.UI.Tab.Publisher
 {
-    public class PublisherViewModel : BaseViewModel, ITabToolbarCommands, ITabHostWindowNotify, IPublishDestination
+    public class PublisherViewModel : BaseViewModel, IDisposable, ITabToolbarCommands, ITabHostWindowNotify, IPublishDestination
     {
         private readonly IConnection connection;
         private readonly IExampleGenerator exampleGenerator;
@@ -197,6 +198,19 @@ namespace PettingZoo.UI.Tab.Publisher
         public ICommand ImportCommand => importCommand;
 
 
+        private readonly DispatcherTimer publishedVisibilityTimer = new()
+        {
+            Interval = TimeSpan.FromSeconds(1)
+        };
+
+        private Visibility publishedVisibility = Visibility.Hidden;
+        public Visibility PublishedVisibility
+        {
+            get => publishedVisibility;
+            set => SetField(ref publishedVisibility, value);
+        }
+
+
         public string Title => SendToQueue
             ? string.IsNullOrWhiteSpace(Queue) ? PublisherViewStrings.TabTitleEmpty :
             string.Format(PublisherViewStrings.TabTitle, Queue)
@@ -244,17 +258,51 @@ namespace PettingZoo.UI.Tab.Publisher
 
 
             PropertyChanged += (_, _) => { saveCommand.RaiseCanExecuteChanged(); };
+
+
+            // ReSharper disable once ConditionIsAlwaysTrueOrFalse - null in design time
+            if (connection != null)
+                connection.StatusChanged += ConnectionStatusChanged;
+
+            publishedVisibilityTimer.Tick += (_, _) =>
+            {
+                PublishedVisibility = Visibility.Hidden;
+                publishedVisibilityTimer.Stop();
+            };
+        }
+
+
+        public void Dispose()
+        {
+            connection.StatusChanged -= ConnectionStatusChanged;
+            GC.SuppressFinalize(this);
+        }
+
+
+        private void ConnectionStatusChanged(object? sender, StatusChangedEventArgs e)
+        {
+            Application.Current.Dispatcher.BeginInvoke(() =>
+            {
+                publishCommand.RaiseCanExecuteChanged();
+            });
         }
 
         
         private void PublishExecute()
         {
             messageTypePublishCommand?.Execute(null);
+
+            PublishedVisibility = Visibility.Visible;
+            publishedVisibilityTimer.Stop();
+            publishedVisibilityTimer.Start();
         }
 
 
         private bool PublishCanExecute()
         {
+            if (connection.Status != ConnectionStatus.Connected)
+                return false;
+
             if (SendToExchange)
             {
                 if (string.IsNullOrWhiteSpace(Exchange) || string.IsNullOrWhiteSpace(RoutingKey))
@@ -571,6 +619,8 @@ namespace PettingZoo.UI.Tab.Publisher
                 SelectedStoredMessage = StoredMessages[0];
                 ActiveStoredMessage = StoredMessages[1];
             };
+
+            PublishedVisibility = Visibility.Visible;
         }
 
         public override Visibility ExchangeVisibility => Visibility.Visible;

PettingZoo/UI/Tab/Publisher/PublisherViewStrings.Designer.cs

@@ -177,6 +177,15 @@ namespace PettingZoo.UI.Tab.Publisher {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to Message published.
+        /// </summary>
+        public static string Published {
+            get {
+                return ResourceManager.GetString("Published", resourceCulture);
+            }
+        }
+        
         /// <summary>
         ///   Looks up a localized string similar to Re: .
         /// </summary>

PettingZoo/UI/Tab/Publisher/PublisherViewStrings.resx

@@ -156,6 +156,9 @@
   <data name="PanelTitleMessages" xml:space="preserve">
     <value>Saved messages</value>
   </data>
+  <data name="Published" xml:space="preserve">
+    <value>Message published</value>
+  </data>
   <data name="ReplyToCorrelationIdPrefix" xml:space="preserve">
     <value>Re: </value>
   </data>

PettingZoo/UI/Tab/Subscriber/SubscriberView.xaml

@@ -37,8 +37,8 @@
             <ListBox.ItemsSource>
                 <CompositeCollection>
                     <CollectionContainer Collection="{Binding Source={StaticResource Messages}}" />
-                    <ListBoxItem HorizontalContentAlignment="Stretch" IsEnabled="False" IsHitTestVisible="False">
+                    <ListBoxItem HorizontalContentAlignment="Stretch" IsEnabled="False" IsHitTestVisible="False" Visibility="{Binding UnreadMessagesVisibility}">
-                        <Grid Visibility="{Binding UnreadMessagesVisibility}">
+                        <Grid>
                             <Grid.ColumnDefinitions>
                                 <ColumnDefinition SharedSizeGroup="DateTime" />
                                 <ColumnDefinition Width="Auto" />
@@ -51,6 +51,17 @@
                         </Grid>                    
                     </ListBoxItem>
                     <CollectionContainer Collection="{Binding Source={StaticResource UnreadMessages}}" />
+                    <ListBoxItem HorizontalContentAlignment="Stretch" IsEnabled="False" IsHitTestVisible="False" Visibility="{Binding StatusVisibility}">
+                        <Grid>
+                            <Grid.ColumnDefinitions>
+                                <ColumnDefinition SharedSizeGroup="DateTime" />
+                                <ColumnDefinition Width="Auto" />
+                                <ColumnDefinition Width="*" />
+                            </Grid.ColumnDefinitions>
+
+                            <TextBlock Grid.Column="1" Text="{Binding StatusText}" HorizontalAlignment="Center" Background="{Binding Background, RelativeSource={RelativeSource AncestorType={x:Type ListBoxItem}}}" Foreground="{x:Static SystemColors.GrayTextBrush}" />
+                        </Grid>
+                    </ListBoxItem>
                 </CompositeCollection>
             </ListBox.ItemsSource>
             <ListBox.ItemTemplate>

PettingZoo/UI/Tab/Subscriber/SubscriberViewModel.cs

@@ -25,7 +25,7 @@ namespace PettingZoo.UI.Tab.Subscriber
     {
         private readonly ILogger logger;
         private readonly ITabFactory tabFactory;
-        private readonly IConnection? connection;
+        private readonly IConnection connection;
         private readonly ISubscriber subscriber;
         private readonly IExportImportFormatProvider exportImportFormatProvider;
         private ReceivedMessageInfo? selectedMessage;
@@ -106,8 +106,14 @@ namespace PettingZoo.UI.Tab.Subscriber
         public Visibility ReplyTabVisibility => IsReplyTab ? Visibility.Visible : Visibility.Collapsed;
         // ReSharper restore UnusedMember.Global
 
+        private readonly Guid subscribeConnectionId;
+        private ConnectionStatus connectionStatus = ConnectionStatus.Connecting;
 
-        public SubscriberViewModel(ILogger logger, ITabFactory tabFactory, IConnection? connection, ISubscriber subscriber, IExportImportFormatProvider exportImportFormatProvider, bool isReplyTab)
+        public Visibility StatusVisibility => connectionStatus is ConnectionStatus.Connecting or ConnectionStatus.Disconnected or ConnectionStatus.Error ? Visibility.Visible : Visibility.Collapsed;
+        public string StatusText => connectionStatus == ConnectionStatus.Connecting ? SubscriberViewStrings.StatusConnecting : SubscriberViewStrings.StatusDisconnected;
+
+
+        public SubscriberViewModel(ILogger logger, ITabFactory tabFactory, IConnection connection, ISubscriber subscriber, IExportImportFormatProvider exportImportFormatProvider, bool isReplyTab)
         {
             IsReplyTab = isReplyTab;
 
@@ -133,6 +139,8 @@ namespace PettingZoo.UI.Tab.Subscriber
 
             createPublisherCommand = new DelegateCommand(CreatePublisherExecute, CreatePublisherCanExecute);
 
+            subscribeConnectionId = connection.ConnectionId;
+            connection.StatusChanged += ConnectionStatusChanged;
             subscriber.MessageReceived += SubscriberMessageReceived;
             subscriber.Start();
         }
@@ -141,11 +149,47 @@ namespace PettingZoo.UI.Tab.Subscriber
         public void Dispose()
         {
             GC.SuppressFinalize(this);
+            connection.StatusChanged -= ConnectionStatusChanged;
             newMessageTimer?.Dispose();
             subscriber.Dispose();
         }
 
 
+        private void ConnectionStatusChanged(object? sender, StatusChangedEventArgs e)
+        {
+            // If another connection has been made, this does not concern us
+            if (e.ConnectionId != subscribeConnectionId)
+                return;
+
+            // The subscriber will not reconnect, so after the first disconnect it's over for us
+            if (connectionStatus is ConnectionStatus.Disconnected)
+                return;
+
+            switch (e.Status)
+            {
+                case ConnectionStatus.Connecting:
+                case ConnectionStatus.Error:
+                    return;
+
+                case ConnectionStatus.Connected:
+                    connectionStatus = ConnectionStatus.Connected;
+                    break;
+
+                case ConnectionStatus.Disconnected:
+                default:
+                    connectionStatus = ConnectionStatus.Disconnected;
+                    break;
+            }
+
+            Application.Current.Dispatcher.BeginInvoke(() =>
+            {
+
+                RaisePropertyChanged(nameof(StatusVisibility));
+                RaisePropertyChanged(nameof(StatusText));
+            });
+        }
+
+
         private void ClearExecute()
         {
             Messages.Clear();
@@ -254,7 +298,7 @@ namespace PettingZoo.UI.Tab.Subscriber
 
         private void CreatePublisherExecute()
         {
-            if (connection == null)
+            if (connection.Status != ConnectionStatus.Connected)
                 return;
 
             tabFactory.CreatePublisherTab(connection, SelectedMessage);
@@ -263,7 +307,7 @@ namespace PettingZoo.UI.Tab.Subscriber
 
         private bool CreatePublisherCanExecute()
         {
-            return connection != null && SelectedMessage != null;
+            return SelectedMessage != null;
         }
 
 

PettingZoo/UI/Tab/Subscriber/SubscriberViewStrings.Designer.cs

@@ -194,5 +194,23 @@ namespace PettingZoo.UI.Tab.Subscriber {
                 return ResourceManager.GetString("ReplyTabTitle", resourceCulture);
             }
         }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Connecting....
+        /// </summary>
+        public static string StatusConnecting {
+            get {
+                return ResourceManager.GetString("StatusConnecting", resourceCulture);
+            }
+        }
+        
+        /// <summary>
+        ///   Looks up a localized string similar to Disconnected.
+        /// </summary>
+        public static string StatusDisconnected {
+            get {
+                return ResourceManager.GetString("StatusDisconnected", resourceCulture);
+            }
+        }
     }
 }

PettingZoo/UI/Tab/Subscriber/SubscriberViewStrings.resx

@@ -162,4 +162,10 @@
   <data name="ReplyTabTitle" xml:space="preserve">
     <value>Replies</value>
   </data>
+  <data name="StatusConnecting" xml:space="preserve">
+    <value>Connecting...</value>
+  </data>
+  <data name="StatusDisconnected" xml:space="preserve">
+    <value>Disconnected</value>
+  </data>
 </root>

PettingZoo/UI/Tab/ViewTabFactory.cs

@@ -36,7 +36,7 @@ namespace PettingZoo.UI.Tab
         }
 
 
-        public void CreateSubscriberTab(IConnection? connection, ISubscriber subscriber)
+        public void CreateSubscriberTab(IConnection connection, ISubscriber subscriber)
         {
             InternalCreateSubscriberTab(connection, subscriber, false);
         }
@@ -75,7 +75,7 @@ namespace PettingZoo.UI.Tab
         }
 
 
-        private ITab InternalCreateSubscriberTab(IConnection? connection, ISubscriber subscriber, bool isReplyTab)
+        private ITab InternalCreateSubscriberTab(IConnection connection, ISubscriber subscriber, bool isReplyTab)
         {
             var viewModel = new SubscriberViewModel(logger, this, connection, subscriber, exportImportFormatProvider, isReplyTab);
             var tab = new ViewTab<SubscriberView, SubscriberViewModel>(