fsignalr

Description:

fsignalr

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');
}
}
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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)