Issue110 (#115)

* Issue 110

* Issue 110

lib/src/connectionhandling/mqtt_connection_handler_base.dart

@@ -163,7 +163,7 @@ abstract class MqttConnectionHandlerBase implements MqttIConnectionHandler {
     } else {
       MqttLogger.log(
           'MqttConnectionHandlerBase::autoReconnect - auto reconnect failed - re trying');
-      clientEventBus!.fire(MqttAutoReconnect());
+      clientEventBus?.fire(MqttAutoReconnect());
     }
   }
 
@@ -265,6 +265,7 @@ abstract class MqttConnectionHandlerBase implements MqttIConnectionHandler {
     MqttLogger.log(
         'MqttConnectionHandlerBase::_performConnectionDisconnect entered');
     connectionStatus.state = MqttConnectionState.disconnected;
+    clientEventBus = null;
   }
 
   /// Processes the connect acknowledgement message.

test/issues/issue110/issue110.dart

@@ -0,0 +1,223 @@
+/*
+ * Package : mqtt5_client
+ * Author : S. Hamblett <[email protected]>
+ * Date   : 10/05/2020
+ * Copyright :  S.Hamblett
+ */
+
+import 'dart:async';
+import 'dart:io';
+import 'package:mqtt5_client/mqtt5_client.dart';
+import 'package:mqtt5_client/mqtt5_server_client.dart';
+
+/// To test the auto reconnect feature this example uses a Mosquitto broker running on local host, any will do
+/// as long as you can break its connection to this process. You could wait for the first pong callback to print out
+/// (these are every 5 seconds) then stop/break connection to the server and reinstate it.
+///
+final clientA = MqttServerClient('localhost', '');
+final clientB = MqttServerClient('test.mosquitto.org', '');
+
+Future<int> main() async {
+  /// A websocket URL must start with ws:// or wss:// or Dart will throw an exception, consult your websocket MQTT broker
+  /// for details.
+  /// To use websockets add the following lines -:
+  /// client.useWebSocket = true;
+  /// client.port = 80;  ( or whatever your WS port is)
+  /// There is also an alternate websocket implementation for specialist use, see useAlternateWebSocketImplementation
+  /// Note do not set the secure flag if you are using wss, the secure flags is for TCP sockets only.
+  /// You can also supply your own websocket protocol list or disable this feature using the websocketProtocols
+  /// setter, read the API docs for further details here, the vast majority of brokers will support the client default
+  /// list so in most cases you can ignore this.
+
+  /// Set logging on if needed, defaults to off
+  clientA.logging(on: true);
+  clientB.logging(on: true);
+
+  /// The client keep alive mechanism is defaulted to off, to enable it set [keepAlivePeriod] below to
+  /// a positive value other than 0.
+  clientA.keepAlivePeriod = 5;
+  clientB.keepAlivePeriod = 5;
+
+  /// Set auto reconnect
+  clientA.autoReconnect = true;
+
+  /// If you do not want active confirmed subscriptions to be automatically re subscribed
+  /// by the auto connect sequence do the following, otherwise leave this defaulted.
+  clientA.resubscribeOnAutoReconnect = false;
+
+  /// Add an auto reconnect callback.
+  /// This is the 'pre' auto re connect callback, called before the sequence starts.
+  clientA.onAutoReconnect = onAutoReconnect;
+
+  /// Add an auto reconnect callback.
+  /// This is the 'post' auto re connect callback, called after the sequence
+  /// has completed. Note that re subscriptions may be occurring when this callback
+  /// is invoked. See [resubscribeOnAutoReconnect] above.
+  clientA.onAutoReconnected = onAutoReconnected;
+
+  /// Add the successful connection callback if you need one.
+  /// This will be called after [onAutoReconnect] but before [onAutoReconnected]
+  clientA.onConnected = onConnectedA;
+  clientB.onConnected = onConnectedB;
+
+  /// Add a subscribed callback, there is also an unsubscribed callback if you need it.
+  /// You can add these before connection or change them dynamically after connection if
+  /// you wish. There is also an onSubscribeFail callback for failed subscriptions, these
+  /// can fail either because you have tried to subscribe to an invalid topic or the broker
+  /// rejects the subscribe request.
+  clientA.onSubscribed = onSubscribed;
+
+  /// Set a ping received callback if needed, called whenever a ping response(pong) is received
+  /// from the broker.
+  clientA.pongCallback = pong;
+
+  /// Create a connection message to use or use the default one. The default one sets the
+  /// client identifier, any supplied username/password, the default keepalive interval(60s)
+  /// and clean session, an example of a specific one below.
+  final connMessA = MqttConnectMessage()
+      .withClientIdentifier('Mqtt_MyClientUniqueIdA')
+      .startClean(); // Non persistent session for testing
+  clientA.connectionMessage = connMessA;
+
+  final connMessB = MqttConnectMessage()
+      .withClientIdentifier('Mqtt_MyClientUniqueIdB')
+      .startClean(); // Non persistent session for testing
+  print('EXAMPLE::Mosquitto client connecting....');
+  clientB.connectionMessage = connMessB;
+
+  /// Connect the client, any errors here are communicated by raising of the appropriate exception. Note
+  /// in some circumstances the broker will just disconnect us, see the spec about this, we however will
+  /// never send malformed messages.
+  print('EXAMPLE::Mosquitto client A connecting....');
+  try {
+    await clientA.connect();
+  } on Exception catch (e) {
+    print('EXAMPLE::client A exception - $e');
+    clientA.disconnect();
+  }
+
+  /// Check we are connected
+  if (clientA.connectionStatus!.state == MqttConnectionState.connected) {
+    print('EXAMPLE::Mosquitto client A connected');
+  } else {
+    /// Use status here rather than state if you also want the broker return code.
+    print(
+        'EXAMPLE::ERROR Mosquitto client A connection failed - disconnecting, status is ${clientA.connectionStatus}');
+    clientA.disconnect();
+    exit(-1);
+  }
+
+  /// Ok, lets try a subscription
+  print('EXAMPLE::Subscribing to the test/lol topic');
+  const topic = 'test/lol'; // Not a wildcard topic
+  clientA.subscribe(topic, MqttQos.atMostOnce);
+
+  /// The client has a change notifier object(see the Observable class) which we then listen to to get
+  /// notifications of published updates to each subscribed topic.
+  clientA.updates.listen((List<MqttReceivedMessage<MqttMessage>> c) {
+    final recMess = c[0].payload as MqttPublishMessage;
+    final pt = MqttUtilities.bytesToStringAsString(recMess.payload.message!);
+
+    /// The above may seem a little convoluted for users only interested in the
+    /// payload, some users however may be interested in the received publish message,
+    /// lets not constrain ourselves yet until the package has been in the wild
+    /// for a while.
+    /// The payload is a byte buffer, this will be specific to the topic
+    print(
+        'EXAMPLE::Change notification:: topic is <${c[0].topic}>, payload is <-- $pt -->');
+    print('');
+  });
+
+  /// If needed you can listen for published messages that have completed the publishing
+  /// handshake which is Qos dependant. Any message received on this stream has completed its
+  /// publishing handshake with the broker.
+  clientA.published!.listen((MqttPublishMessage message) {
+    print(
+        'EXAMPLE::Published notification:: topic is ${message.variableHeader!.topicName}, with Qos ${message.header!.qos}');
+  });
+
+  /// Lets publish to our topic
+  /// Use the payload builder rather than a raw buffer
+  /// Our known topic to publish to
+  const pubTopic = 'Dart/Mqtt_client/testtopic';
+  final builder = MqttPayloadBuilder();
+  builder.addString('Hello from mqtt_client');
+
+  /// Subscribe to it
+  print('EXAMPLE::Subscribing to the Dart/Mqtt_client/testtopic topic');
+  clientA.subscribe(pubTopic, MqttQos.exactlyOnce);
+
+  /// Publish it
+  print('EXAMPLE::Publishing our topic');
+  clientA.publishMessage(pubTopic, MqttQos.exactlyOnce, builder.payload!);
+
+  /// Ok, we will now sleep a while, in this gap you will see ping request/response
+  /// messages being exchanged by the keep alive mechanism.
+  print('EXAMPLE::Sleeping....');
+  await MqttUtilities.asyncSleep(120);
+
+  /// Finally, unsubscribe and exit gracefully
+  print('EXAMPLE::Unsubscribing');
+  clientA.unsubscribeStringTopic(topic);
+
+  /// Wait for the unsubscribe message from the broker if you wish.
+  await MqttUtilities.asyncSleep(2);
+  print('EXAMPLE::Disconnecting');
+  clientA.disconnect();
+  return 0;
+}
+
+/// The subscribed callback
+void onSubscribed(MqttSubscription subscription) {
+  print(
+      'EXAMPLE::Subscription confirmed for topic ${subscription.topic.rawTopic}');
+}
+
+// The pre auto re connect callback
+void onAutoReconnect() {
+  print(
+      'EXAMPLE::onAutoReconnect client A callback - Client auto reconnection sequence will start');
+}
+
+/// The post auto re connect callback
+void onAutoReconnected() async {
+  print(
+      'EXAMPLE::onAutoReconnected client callback - Client A auto reconnection sequence has completed');
+  clientA.disconnect();
+  print('EXAMPLE::Mosquitto client A connecting....');
+  try {
+    await clientB.connect();
+  } on Exception catch (e) {
+    print('EXAMPLE::client B exception - $e');
+    clientB.disconnect();
+  }
+
+  /// Check we are connected
+  if (clientB.connectionStatus!.state == MqttConnectionState.connected) {
+    print('EXAMPLE::Mosquitto client B connected');
+  } else {
+    /// Use status here rather than state if you also want the broker return code.
+    print(
+        'EXAMPLE::ERROR Mosquitto client B connection failed - disconnecting, status is ${clientB.connectionStatus}');
+    clientB.disconnect();
+    exit(-1);
+  }
+}
+
+/// The successful connect callback
+void onConnectedA() {
+  print(
+      'EXAMPLE::OnConnected client A callback - Client connection was successful');
+}
+
+// The successful connect callback
+void onConnectedB() {
+  print(
+      'EXAMPLE::OnConnected client B callback - Client connection was successful');
+}
+
+/// Pong callback
+void pong() {
+  print(
+      'EXAMPLE::Ping response client callback invoked - you may want to disconnect your broker here');
+}