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Configuring Client

Create CourierClient​

CourierClient is the class that we use for any MQTT tasks such as connection, subscription, send and receive message. To initialize an instance of CourierClient we can use the static method like so.

Create CourierClient​

CourierClient is the class that we use for any MQTT tasks such as connection, subscription, send and receive message. To initialize an instance of CourierClient we can use the static method like so.

final CourierClient courierClient = CourierClient.create(
    authProvider: DioAuthProvider(
          dio: Dio(),
          tokenApi: apiUrl,
          authResponseMapper: CourierResponseMapper()),
      config: CourierConfiguration(
          authRetryPolicy: DefaultAuthRetryPolicy(),
          readTimeoutSeconds: 60,
      ),
      messageAdapters: const <MessageAdapter>[
          JSONMessageAdapter(),
          BytesMessageAdapter(),
          StringMessageAdapter()
      ])
  ;

AuthProvider​

This is an interface containing method to fetchConnectOptions used by the Client to connect to broker

Required Configs​

  • authRetryPolicy: Retry policy used to handle retry when tokenAPI URL fails
  • messageAdapters: List of MessageAdapters used to encode model to bytes and decode bytes to object. Prioritization will be based on the order of the adapter in the list. We provide built-in adapters such as: JSONMessageAdapter,BytesMessageAdapter, & StringMessageAdapter. Optionally, you can also depends on courier_protobuf lib to use ProtobufMessageAdapter.

Setup CourierClient with DioAuthProvider​

To fetch ConnectionCredential (host, port, etc) from HTTP endpoint, you can use DioAuthProvider passing these params.

  • Dio : We use dio package for making HTTP request. This will provide you flexibility to use your own Dio instance in case you have various custom headers need to be sent to the server (e.g Authentication, etc).

  • tokenApi: An endpoint URL that returns JSON containing credential for mapping to CourierConnectOptions.

  • authResponseMapper: Instance of AuthResponseMapper for mapping JSON returned by tokenAPI URL to CourierConnectOptions.

Providing Token API URL with JSON Credential Response​

To connect to MQTT broker you need to provide an endpoint URL that returns JSON containing these payload. 

{
    "clientId": "randomcourier1234567",
    "username": "randomcourier1234567",
    "password": "randomcourier4321",
    "host": "broker.mqttdashboard.com",
    "port": 1883,
    "cleanSession": true,
    "keepAlive": 45
}

Map JSON to CourierConnectOptions​

You need to create and implement AuthResponseMapper to map the JSON to the CourierConnectOptions instance.

class CourierResponseMapper implements AuthResponseMapper {
  @override
  CourierConnectOptions map(Map<String, dynamic> response) => CourierConnectOptions(
      clientId: response["clientId"],
      username: response["username"],
      host: response["host"],
      port: response["port"],
      cleanSession: response["cleanSession"],
      keepAliveSeconds: response["keepAlive"],
      password: response['password']
  );
}

Setup CourierClient with your own AuthProvider​

In case you want to fetch the connect options using your own implementation, you can implement AuthProvider interface like so.

// Example of fetching connectOptions locally without making remote HTTP API Call.
class LocalAuthProvider implements AuthProvider {
  final CourierConnectOptions connectOptions;

  LocalAuthProvider({required this.connectOptions});

  @override
  Future<CourierConnectOptions> fetchConnectOptions() {
    return Future<CourierConnectOptions>.value(connectOptions);
  }
}

final CourierClient courierClient = CourierClient.create(
    authProvider: LocalAuthProvider(
          connectOptions: CourierConnectOptions(
              clientId: const Uuid().v4(),
              username: "randomcourier1234567",
              host: "broker.mqttdashboard.com",
              port: 1883,
              cleanSession: true,
              keepAliveSeconds: 45,
              password: "1234")),
      config: CourierConfiguration(
          authRetryPolicy: DefaultAuthRetryPolicy(),
          readTimeoutSeconds: 60,
      ),
      //...
  );

Optional Configs​

  • timerPingSenderEnabled: Whether Courier should use timerPingSender internally (Android only). It defines the logic of sending ping requests over the MQTT connection. Default to true.

  • activityCheckIntervalSeconds: Interval at which channel activity is checked for unacknowledged MQTT packets.. Default to 12.

  • inactivityTimeoutSeconds: When acknowledgement for an MQTT packet is not received within this interval, the connection is reestablished. Default to 10.

  • readTimeoutSeconds: The read timeout of the connection. Default to 40.

  • connectRetryPolicyConfig: A config to determine the retry policy. Default baseRetryTimeSeconds to 1 and maxRetryTimeSeconds to 30.

  • connectTimeoutConfig: A config to determine the connect timeout. Default socketTimeout to 10 and handshakeTimeout to 10.