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A wrapper around our Cocoa and Java client library SDKs

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Ably Flutter Plugin

A Flutter plugin wrapping the ably-cocoa (iOS) and ably-java (Android) client library SDKs for Ably, the platform that powers synchronized digital experiences in realtime.

Ably provides the best infrastructure and APIs to power realtime experiences at scale, delivering billions of realtime messages everyday to millions of end users. We handle the complexity of realtime messaging so you can focus on your code.

Resources

Supported Platforms

iOS

iOS 10 or newer.

Android

API Level 19 (Android 4.4, KitKat) or newer.

This project uses Java 8 language features, utilising Desugaring to support lower versions of the Android runtime (i.e. API Levels prior to 24)

If your project needs support for SDK Version lower than 24, Android Gradle Plugin 4.0.0+ must be used. You might also need to upgrade gradle distribution accordingly.

Known Limitations

Features that we do not currently support, but we do plan to add in the future:

Example app

Running example app

Android Studio / IntelliJ Idea

Under the run/ debug configuration drop down menu, click Edit Configurations.... Duplicate the Example App (Duplicate and modify) configuration. Leave the “Store as project file” unchecked to avoid committing your Ably API key into a repository. Update this new run configuration’s additional run args with your ably API key. Run or debug the your new run/ debug configuration.

Visual Studio Code

Command Line using the Flutter Tool

Push Notifications

See PushNotifications.md for detailed information on getting PN working with the example app.

Troubleshooting

Usage

Specify Dependency

Package home: pub.dev/packages/ably_flutter

See: Adding a package dependency to an app

Import the package

import 'package:ably_flutter/ably_flutter.dart' as ably;

Configure a Client Options object

For guidance on selecting an authentication method (basic authentication vs. token authentication), read Selecting an authentication mechanism.

Authenticating using basic authentication/ API key (for running example app/ test apps and not for production)

// Specify your apiKey with `flutter run --dart-define=ABLY_API_KEY=replace_your_api_key`
final String ablyApiKey = const String.fromEnvironment(Constants.ablyApiKey);
final clientOptions = ably.ClientOptions.fromKey(ablyApiKey);
clientOptions.logLevel = ably.LogLevel.verbose;  // optional

Authenticating using token authentication

// Used to create a clientId when a client first doesn't have one. 
// Note: you should implement `createTokenRequest`, which makes a request to your server that uses your Ably API key directly.
final clientOptions = ably.ClientOptions()
// ..clientId = _clientId // Optionally set the clientId
  ..autoConnect = false
  ..authCallback = (TokenParams tokenParams) async {
    try {
      // If a clientId was set in ClientOptions, it will be available in Ably.TokenParams.
      final tokenRequestMap =
      await createTokenRequest(tokenParams: tokenParams);
      return ably.TokenRequest.fromMap(tokenRequestMap);
    } catch (e) {
      print("Something went wrong in the authCallback:");
      print(e);
    }
  };
this._ablyClient = new ably.Realtime(options: clientOptions);
await this._ablyClient.connect();

Using the REST API

Creating the REST client instance:

ably.Rest rest = ably.Rest(options: clientOptions);

Getting a channel instance

ably.RestChannel channel = rest.channels.get('test');

Publishing messages using REST:

// both name and data
await channel.publish(name: "Hello", data: "Ably");

// just name
await channel.publish(name: "Hello");

// just data
await channel.publish(data: "Ably");

// an empty message
await channel.publish();

Get REST history:

void getHistory([ably.RestHistoryParams params]) async {
  // getting channel history, by passing or omitting the optional params
  var result = await channel.history(params);

  var messages = result.items;        // get messages
  var hasNextPage = result.hasNext(); // tells whether there are more results
  if (hasNextPage) {    
    result = await result.next();     // will fetch next page results
    messages = result.items;
  }
  if (!hasNextPage) {
    result = await result.first();    // will fetch first page results
    messages = result.items;
  }
}

// history with default params
getHistory();

// sorted and filtered history
getHistory(ably.RestHistoryParams(direction: 'forwards', limit: 10));

Get REST Channel Presence:

void getPresence([ably.RestPresenceParams params]) async {
  // getting channel presence members, by passing or omitting the optional params
  var result = await channel.presence.get(params);

  var presenceMembers = result.items; // returns PresenceMessages
  var hasNextPage = result.hasNext(); // tells whether there are more results
  if (hasNextPage) {
    result = await result.next();     // will fetch next page results
    presenceMembers = result.items;
  }
  if (!hasNextPage) {
    result = await result.first();    // will fetch first page results
    presenceMembers = result.items;
  }
}

// getting presence members with default params
getPresence();

// filtered presence members
getPresence(ably.RestPresenceParams(
  limit: 10,
  clientId: '<clientId>',
  connectionId: '<connectionID>',
));

Get REST Presence History:

void getPresenceHistory([ably.RestHistoryParams params]) async {

  // getting channel presence history, by passing or omitting the optional params
  var result = await channel.presence.history(params);

  var presenceHistory = result.items; // returns PresenceMessages
  var hasNextPage = result.hasNext(); // tells whether there are more results
  if (hasNextPage) {
    result = await result.next();     // will fetch next page results
    presenceHistory = result.items;
  }
  if (!hasNextPage) {
    result = await result.first();    // will fetch first page results
    presenceHistory = result.items;
  }
}

// getting presence members with default params
getPresenceHistory();

// filtered presence members
getPresenceHistory(ably.RestHistoryParams(direction: 'forwards', limit: 10));

Using the Realtime API

Creating the Realtime client instance:

ably.Realtime realtime = ably.Realtime(options: clientOptions);

Listening for connection state change events:

realtime.connection
  .on()
  .listen((ably.ConnectionStateChange stateChange) async {
    print('Realtime connection state changed: ${stateChange.event}');
    setState(() {
      _realtimeConnectionState = stateChange.current;
    });
});

Listening for a particular connection state change event (e.g. connected):

realtime.connection
  .on(ably.ConnectionEvent.connected)
  .listen((ably.ConnectionStateChange stateChange) async {
    print('Realtime connection state changed: ${stateChange.event}');
    setState(() {
      _realtimeConnectionState = stateChange.current;
    });
});

Creating a Realtime channel instance:

ably.RealtimeChannel channel = realtime.channels.get('channel-name');

Listening for channel events:

channel.on().listen((ably.ChannelStateChange stateChange) {
  print("Channel state changed: ${stateChange.current}");
});

Attaching to the channel:

await channel.attach();

Detaching from the channel:

await channel.detach();

Subscribing to messages on the channel:

var messageStream = channel.subscribe();
var channelMessageSubscription = messageStream.listen((ably.Message message) {
  print("New message arrived ${message.data}");
});

Use channel.subscribe(name: "event1") or channel.subscribe(names: ["event1", "event2"]) to listen to specific named messages.

UnSubscribing from receiving messages on the channel:

await channelMessageSubscription.cancel();

Publishing channel messages

// both name and data
await channel.publish(name: "event1", data: "hello world");
await channel.publish(name: "event1", data: {"hello": "world", "hey": "ably"});
await channel.publish(name: "event1", data: [{"hello": {"world": true}, "ably": {"serious": "realtime"}]);

// single message
await channel.publish(message: ably.Message()..name = "event1"..data = {"hello": "world"});

// multiple messages
await channel.publish(messages: [
  ably.Message()..name="event1"..data = {"hello": "ably"},
  ably.Message()..name="event1"..data = {"hello": "world"}
]);

Get Realtime history

void getHistory([ably.RealtimeHistoryParams params]) async {
  var result = await channel.history(params);

  var messages = result.items;        // get messages
  var hasNextPage = result.hasNext(); // tells whether there are more results
  if (hasNextPage) {    
    result = await result.next();     // will fetch next page results
    messages = result.items;
  }
  if (!hasNextPage) {
    result = await result.first();    // will fetch first page results
    messages = result.items;
  }
}

// history with default params
getHistory();

// sorted and filtered history
getHistory(ably.RealtimeHistoryParams(direction: 'forwards', limit: 10));

Enter Realtime Presence:

await channel.presence.enter();

// with data
await channel.presence.enter("hello");
await channel.presence.enter([1, 2, 3]);
await channel.presence.enter({"key": "value"});

// with Client ID
await channel.presence.enterClient("user1");

// with Client ID and data
await channel.presence.enterClient("user1", "hello");
await channel.presence.enterClient("user1", [1, 2, 3]);
await channel.presence.enterClient("user1", {"key": "value"});

Update Realtime Presence:

await channel.presence.update();

// with data
await channel.presence.update("hello");
await channel.presence.update([1, 2, 3]);
await channel.presence.update({"key": "value"});

// with Client ID
await channel.presence.updateClient("user1");

// with Client ID and data
await channel.presence.updateClient("user1", "hello");
await channel.presence.updateClient("user1", [1, 2, 3]);
await channel.presence.updateClient("user1", {"key": "value"});

Leave Realtime Presence:

await channel.presence.leave();

// with data
await channel.presence.leave("hello");
await channel.presence.leave([1, 2, 3]);
await channel.presence.leave({"key": "value"});

// with Client ID
await channel.presence.leaveClient("user1");

// with Client ID and data
await channel.presence.leaveClient("user1", "hello");
await channel.presence.leaveClient("user1", [1, 2, 3]);
await channel.presence.leaveClient("user1", {"key": "value"});

Get Realtime Presence members:

var presenceMessages = await channel.presence.get();

// filter by Client Id
var presenceMessages = await channel.presence.get(
  ably.RealtimePresenceParams(
    clientId: 'clientId',
  ),
);

// filter by Connection Id
var presenceMessages = await channel.presence.get(
  ably.RealtimePresenceParams(
    connectionId: 'connectionId',
  ),
);

Get Realtime Presence history

void getPresenceHistory([ably.RealtimeHistoryParams params]) async {
  var result = await channel.presence.history(params);

  var messages = result.items;        // get messages
  var hasNextPage = result.hasNext(); // tells whether there are more results
  if (hasNextPage) {    
    result = await result.next();     // will fetch next page results
    messages = result.items;
  }
  if (!hasNextPage) {
    result = await result.first();    // will fetch first page results
    messages = result.items;
  }
}

// presence history with default params
getPresenceHistory();

// sorted and filtered history
getPresenceHistory(ably.RealtimeHistoryParams(direction: 'forwards', limit: 10));

Subscribe to Realtime Presence messages

// subscribe for all presence actions
channel
  .presence
  .subscribe()
  .listen((presenceMessage) {
    print(presenceMessage);
  },
);

// subscribe for specific action
channel
  .presence
  .subscribe(action: PresenceAction.enter)
  .listen((presenceMessage) {
    print(presenceMessage);
  },
);

// subscribe for multiple actions
channel
  .presence
  .subscribe(actions: [
    PresenceAction.enter,
    PresenceAction.update,
  ])
  .listen((presenceMessage) {
    print(presenceMessage);
  },
);

Push Notifications

See PushNotifications.md for detailed information on using PN with this plugin.

Caveats

RTE6a compliance

Using the Streams based approach doesn’t fully conform with RTE6a from our client library features specification.

The Problem

StreamSubscription subscriptionToBeCancelled;

// Listener registered 1st
realtime.connection.on().listen((ably.ConnectionStateChange stateChange) async {
  if (stateChange.event == ably.ConnectionEvent.connected) {
    await subscriptionToBeCancelled.cancel();       // Cancelling 2nd listener
  }
});

// Listener registered 2nd
subscriptionToBeCancelled = realtime.connection.on().listen((ably.ConnectionStateChange stateChange) async {
  print('State changed');
});

In the example above, the 2nd listener is cancelled when the 1st listener is notified about the “connected” event. As per RTE6a, the 2nd listener should also be triggered. It will not be as the 2nd listener was registered after the 1st listener and stream subscription is cancelled immediately after 1st listener is triggered.

This wouldn’t have happened if the 2nd listener had been registered before the 1st was.

However, using a neat little workaround will fix this…

The Workaround – Cancelling using delay

Instead of await subscriptionToBeCancelled.cancel();, use

Future.delayed(Duration.zero, () {
    subscriptionToBeCancelled.cancel();
});

Download Ably Flutter Plugin source code on GitHub

https://github.com/ably/ably-flutter
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