Bumblebee

Bumblebee is the Dart & Flutter client library for Pollen, an HTTP pubsub and streaming engine for Rails.

Features

Subscribe to Pollen streams and be notified of message events, streams completion and failure.

Getting started

flutter pub add bumblebee

Usage

Subscribing to a stream

import 'package:bumblebee/bumblebee.dart' as bumblebee;

void subscribe(String streamId) async {
  bumblebee.Event? event = await bumblebee.Client(server: Uri.parse('https://pollen.server.local')).
    .listen(streamId);
  print("Stream completed: ${event?.type}");
}

Listening to stream updates

To start listening to updates, use the listen method and provide the stream ID. As the endpoint should be protected by some authentication scheme, the closure passed as an argument to the listen method can be used to build a custom HTTP request based upon the provided URI.

The call to listen will return as soon as an event with the type completed or failed is pushed by the server.

import 'package:bumblebee/bumblebee.dart' as bumblebee;
import 'package:http/http.dart' as http;

void subscribe(String streamId) async {
  bumblebee.Event? event = await bumblebee.Client(server: Uri.parse('https://pollen.server.local'))
    .onHeartbeat(() {
      print('Received an heartbeat');
    }).onTerminate(() {
      print('Received the "terminated" event');
    }).onMessage((bumblebee.Event event) {
      print('Received an event of type ${event.type}');
      print('Payload: ${event.data()}');
    }).listen(streamId, (uri) {
      final request = http.Request('GET', uri);
      request.headers['authorization'] = 'Bearer: <TOKEN>';
      return request;
    });
  print("Stream completed: ${event?.type}");
  print('Payload: ${event?.data()}');
}

Client timeout

The server will automatically close the stream after the timeout specified on the server-side. You should also probably ensure a timeout is applied on the client side. To do so, use the timeout method:

import 'package:bumblebee/bumblebee.dart' as bumblebee;
import 'package:http/http.dart' as http;

void subscribe(String streamId) async {
  try {
    bumblebee.Event? event = await bumblebee.Client(server: Uri.parse('https://pollen.server.local'))
      .listen(streamId, (uri) {
        final request = http.Request('GET', uri);
        request.headers['authorization'] = 'Bearer: <TOKEN>';
        return request;
      }).timeout(const Duration(seconds: 30));
    print("Stream completed: ${event?.type}");
    print('Payload: ${event?.data()}');
  } on TimeoutException catch (e) {
    print("Client timeout ${e.message}");
  }
}

Handle errors

Connection timeouts and stream failures fired server-side throw StreamTimeoutException and FailureException exceptions, respectively. As Bumblebee uses the http package under the hood, network connectivity issues will throw http.ClientException exceptions.

License

This library is available as open source under the terms of the MIT License.