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Example

Examples:

  • example\flutter_app simple chat application
  • example\console simple console application

Usage

Create client:

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

final client = centrifuge.createClient("ws://localhost:8000/connection/websocket?format=protobuf");

Note that ?format=protobuf is required because this library only works with Protobuf protocol. While this client uses binary Protobuf protocol internally nothing stops you from sending JSON-encoded data over it.

Connect to server:

client.connect();

Note that .connect() method is asynchronous. This means that client will be properly connected and authenticated on server at some point in future. To handle connect and disconnect events you can listen to connectStream and disconnectStream:

client.connectStream.listen(onEvent);
client.disconnectStream.listen(onEvent);
client.connect();

Connect and disconnect events can happen many times throughout client lifetime.

Subscribe to channel:

final subscription = client.getSubscription(channel);

subscription.publishStream.listen(onEvent);
subscription.joinStream.listen(onEvent);  
subscription.leaveStream.listen(onEvent);
subscription.subscribeSuccessStream.listen(onEvent);
subscription.subscribeErrorStream.listen(onEvent);
subscription.unsubscribeStream.listen(onEvent);

subscription.subscribe();

Publish:

final output = jsonEncode({'input': message});
final data = utf8.encode(output);
await subscription.publish(data);

Feature matrix

  • connect to server using JSON protocol format
  • x connect to server using Protobuf protocol format
  • x connect with token (JWT)
  • x connect with custom header
  • x automatic reconnect in case of errors, network problems etc
  • x exponential backoff for reconnect
  • x connect and disconnect events
  • x handle disconnect reason
  • x subscribe on channel and handle asynchronous Publications
  • x handle Join and Leave messages
  • x handle Unsubscribe notifications
  • reconnect on subscribe timeout
  • x publish method of Subscription
  • x unsubscribe method of Subscription
  • presence method of Subscription
  • presence stats method of Subscription
  • x history method of Subscription
  • x top-level publish method
  • top-level presence method
  • top-level presence stats method
  • top-level history method
  • top-level unsubscribe method
  • send asynchronous messages to server
  • x handle asynchronous messages from server
  • x send RPC commands
  • x subscribe to private channels with token (JWT)
  • connection JWT refresh
  • private channel subscription token (JWT) refresh
  • handle connection expired error
  • handle subscription expired error
  • x ping/pong to find broken connection
  • message recovery mechanism for client-side subscriptions
  • x server-side subscriptions
  • x message recovery mechanism for server-side subscriptions
  • history stream pagination

Instructions to update protobuf

  1. Install protoc compiler
  2. Install protoc_plugin https://pub.dev/packages/protoc_plugin (dart pub global activate protoc_plugin)
  3. cd lib/src/proto and run protoc --dart_out=. -I . client.proto
  4. cd to root and run dartfmt -w lib/ test/ (install dartfmt with dart pub global activate dart_style)

Instructions to release

  1. Update changelog
  2. Bump version in pubspec.yaml, push, create new tag
  3. pub publish

Author

German Saprykin, saprykin.h@gmail.com

Libraries

centrifuge