Update TimeoutException message

libraries/Microsoft.Bot.Connector.Streaming/Application/StreamingConnection.cs

@@ -43,6 +43,14 @@ protected StreamingConnection(ILogger logger)
         /// <value>A <see cref="ILogger"/> for the streaming connection.</value>
         protected ILogger Logger { get; }
 
+        /// <summary>
+        /// Gets a value indicating whether this is currently connected.
+        /// </summary>
+        /// <value>
+        /// True if this is currently connected, otherwise false.
+        /// </value>
+        protected bool IsConnected { get; private set; } = false;
+
         /// <summary>
         /// Sends a streaming request through the connection.
         /// </summary>
@@ -65,7 +73,20 @@ public virtual async Task<ReceiveResponse> SendStreamingRequestAsync(StreamingRe
                 throw new InvalidOperationException("Cannot send streaming request since the session is not set up.");
             }
 
-            return await _session.SendRequestAsync(request, cancellationToken).ConfigureAwait(false);
+            try
+            {
+                return await _session.SendRequestAsync(request, cancellationToken).ConfigureAwait(false);
+            }
+            catch (TimeoutException ex)
+            {
+                var timeoutMessage = $"The connection to the client has been disconnected, and the request has timed out after waiting {TaskExtensions.DefaultTimeout.Seconds} seconds for a response.";
+                if (IsConnected)
+                {
+                    timeoutMessage = $"The request sent to the client has timed out after waiting {TaskExtensions.DefaultTimeout.Seconds} seconds for a response.";
+                }
+
+                throw new OperationCanceledException(timeoutMessage, ex, cancellationToken);
+            }
         }
 
         /// <summary>
@@ -96,7 +117,7 @@ public virtual async Task ListenAsync(RequestHandler requestHandler, Cancellatio
             _session = new StreamingSession(requestHandler, _application, Logger, cancellationToken);
 
             // Start transport and application
-            var transportTask = _transport.ConnectAsync(default, cancellationToken);
+            var transportTask = _transport.ConnectAsync((connected) => IsConnected = connected, cancellationToken);
             var applicationTask = _application.ListenAsync(cancellationToken);
 
             var tasks = new List<Task> { transportTask, applicationTask };

libraries/Microsoft.Bot.Connector.Streaming/Application/StreamingTransportClient.cs

@@ -105,7 +105,20 @@ public async Task<ReceiveResponse> SendAsync(StreamingRequest message, Cancellat
                 throw new ArgumentNullException(nameof(message));
             }
 
-            return await _session.SendRequestAsync(message, cancellationToken).ConfigureAwait(false);
+            try
+            {
+                return await _session.SendRequestAsync(message, cancellationToken).ConfigureAwait(false);
+            }
+            catch (TimeoutException ex)
+            {
+                var timeoutMessage = $"The underlying connection has been disconnected, and the request has timed out after waiting {TaskExtensions.DefaultTimeout.Seconds} seconds for a response.";
+                if (IsConnected)
+                {
+                    timeoutMessage = $"The request sent to the underlying connection has timed out after waiting {TaskExtensions.DefaultTimeout.Seconds} seconds for a response.";
+                }
+
+                throw new OperationCanceledException(timeoutMessage, ex, cancellationToken);
+            }
         }
 
         /// <inheritdoc />

libraries/Microsoft.Bot.Connector.Streaming/TaskExtensions.cs

@@ -6,14 +6,14 @@
 using System.Threading.Tasks;
 
 namespace Microsoft.Bot.Connector.Streaming
-{ 
+{
     internal static class TaskExtensions
     {
-        private static readonly TimeSpan _defaultTimeout = TimeSpan.FromSeconds(30);
+        public static readonly TimeSpan DefaultTimeout = TimeSpan.FromSeconds(30);
 
         public static async Task<T> DefaultTimeOutAsync<T>(this Task<T> task)
         {
-            return await task.TimeoutAfterAsync<T>(_defaultTimeout).ConfigureAwait(false);
+            return await task.TimeoutAfterAsync<T>(DefaultTimeout).ConfigureAwait(false);
         }
 
         public static async Task<T> TimeoutAfterAsync<T>(this Task<T> task, TimeSpan timeout)
@@ -41,7 +41,7 @@ public static async Task<T> TimeoutAfterAsync<T>(this Task<T> task, TimeSpan tim
 
         public static async Task DefaultTimeOutAsync(this Task task)
         {
-            await task.TimeoutAfterAsync(_defaultTimeout).ConfigureAwait(false);
+            await task.TimeoutAfterAsync(DefaultTimeout).ConfigureAwait(false);
         }
 
         public static async Task TimeoutAfterAsync(this Task task, TimeSpan timeout)