fsignalr 1.3.0

Signalr client for Flutter to enable integration of real-time communication in Flutter apps.

fsignalr

Signalr client for Flutter.

Usage

import 'package:fsignalr/fsignalr.dart';

class HubMethodHandler {
  final String methodName;
  final int argsCount;
  final void Function(String methodName, List<String?>? args)? handler;

  const HubMethodHandler({
    required this.methodName,
    required this.argsCount,
    required this.handler,
  });
}

const appHubMethodHandlers = [
  HubMethodHandler(
    methodName: 'NoArgsEchoMethod',
    argsCount: 0,
    handler: noArgsMethodHandler,
  ),
  HubMethodHandler(
    methodName: 'OneArgEchoMethod',
    argsCount: 1,
    handler: oneArgMethodHandler,
  ),
  HubMethodHandler(
    methodName: 'TwoArgsEchoMethod',
    argsCount: 2,
    handler: twoArgsMethodHandler,
  ),
];

void noArgsMethodHandler(String methodName, List<String?>? args) {
  print('NoArgsEchoMethod received, args: $args');
}

void oneArgMethodHandler(String methodName, List<String?>? args) {
  print('OneArgEchoMethod received, args: $args');
}

void twoArgsMethodHandler(String methodName, List<String?>? args) {
  print('TwoArgsEchoMethod received, args: $args');
}

Future<void> setUpConnection() async {
  try {
    // Create the hub connection manager
    final HubConnectionManager manager = HubConnectionManager();

    // Initialize the hub connection manager, this must be done
    // before calling any other method on the manager
    await manager.init(
      baseUrl: 'https://myserver.com/hub',
      transportType: TransportType.all,
      headers: {'myHeaderKey': 'myHeaderValue'},
      accessToken: 'myToken',
      handShakeResponseTimeout: const Duration(seconds: 10),
      keepAliveInterval: const Duration(seconds: 20),
      serverTimeout: const Duration(seconds: 30),
      handledHubMethods: appHubMethodHandlers
          .map(
            (appHubMethodHandler) =>
        (
        methodName: appHubMethodHandler.methodName,
        argCount: appHubMethodHandler.argsCount,
        ),
      )
          .toList(),
    );

    // Listen to the connection state
    manager.onHubConnectionStateChangedCallback = (state) {
      print('Connection state changed to: $state');
    };

    // listen to received messages from the server
    // this listener will only be invoked for the hub methods with names that
    // were registered in the handledHubMethods list
    manager.onMessageReceivedCallback = (methodName, args) {
      for (final appHubMethodHandler in appHubMethodHandlers) {
        if (methodName == appHubMethodHandler.methodName) {
          appHubMethodHandler.handler?.call(methodName, args);
          break; // or you can not break if you want to call all
          // the handlers that have the same method name
        }
      }
    };

    // listen to connection-closed callback
    manager.onConnectionClosedCallback = (exception) {
      print('Connection closed, exception: $exception');
    };

    // Start the connection
    await manager.startConnection();

    // invoke methods on the server
    await manager.invoke(
      methodName: 'MyServerMethodName',
      args: ['myFirstArg', 'mySecondArg'],
    );

    // stop the connection
    await manager.stopConnection();

    // start the connection again, if you want :)
    await manager.startConnection();

    // dispose the hub connection manager when done (also stops the connection)
    await manager.dispose();
  } catch (e) {
    print('Error has occurred: $e');
  }
}

Acknowledgements

• For android implementation, uses the official SignalR client for Java by Microsoft.

Limitations

• Currently only works on android
• Currently only supports websocket transport and long polling as per the official documentation
• Min Android sdk supported is 20 reason

Future Work

• ❌ Add support for iOS
• Expose more functionality from the SignalR client for Java (if requested)