isabella232 / dart

PubNub Dart SDK

PubNub Dart SDK

pubnub is a Flutter-friendly SDK written in Dart that allows you to connect to PubNub Data Streaming Network and add real-time features to your application.

Installation

Using pub dependency management tool

pubnub uses the standard pub tool for package management to distribute Dart code.

To add the package to your Dart or Flutter project, add pubnub as a dependency in your pubspec.yaml.

dependencies:
  pubnub: ^1.0.0

After adding the dependency to pubspec.yaml, run the pub get command in the root directory of your project (the same that the pubspec.yaml is in).

Using Git

If you want to use the latest, unreleased version of pubnub, you can add it to pubspec.yaml as a Git package.

dependencies:
  pubnub:
    git: git://github.com/pubnub/dart.git

Using a local copy of the repository

If you want to copy the Dart repository and modify it locally, clone it using git clone https://github.com/pubnub/dart and then import it into pubspec.yaml as follows:

dependencies:
  pubnub:
    path: ../path-to-cloned-pubnub-repo

Importing

After you install the pubnub package, import it in your application. You can import it in one of two ways:

// Import all PubNub objects into your namespace
import 'package:pubnub/core.dart';

// Or import PubNub into a named namespace
import 'package:pubnub/pubnub.dart' as pn;

Usage

Keyset

First, create a Keyset instance:

final myKeyset = Keyset(
  subscribeKey: 'demo',
  publishKey: 'demo',
  uuid: UUID('demo'));

Keyset contains all your configuration. You can use multiple Keysets (with different parameters) if you need.

If you have a PubNub account, replace demo with the key values from your PubNub dashboard. If you don't, you can use the highly rate-limited demo keys, but be aware that the keyset is public, so don't send any sensitive data.

PubNub instance

Next, instantiate the PubNub class, passing myKeyset as a default keyset. This will be used any time a keyset is not passed into a method.

final pubnub = PubNub(defaultKeyset: myKeyset);

Now you can use the pubnub instance to publish messages, subscribe to channels, and everything else!

Publishing messages

To publish a message, use the publish method.

pubnub.publish('my_channel', { 'content': 'Hello world!' });

Messages can be any JSON-serializable object.

If you are going to publish a lot of messages to one channel, you can use channel abstraction to obtain an instance of a Channel.

final myChannel = pubnub.channel('my_channel');

myChannel.publish(200);
myChannel.publish({ 'answer': 42 });

Subscribing to channels

To subscribe to a list of channels or channel groups, use the subscribe method. You need to pass a Set of channels or channel groups.

var subscription = pubnub.subscribe(channels: {'ch1', 'ch2'});

You can also use your Channel instance:

var subscription = myChannel.subscribe();

Both of those methods return a Subscription.

A Subscription contains a Dart Stream messages from the channel(s) to which you are subscribed. You can transform that stream in the usual ways, or add a listener using listen:

subscription.messages.listen((envelope) {
  print(`${envelope.uuid} sent a message: ${envelope.payload}`);
});

var envelope =
      await sub.messages.firstWhere((envelope) => envelope.channel == 'ch2');

Channel history

You can retrieve past messages from a channel in two ways, as follows:

Using channel.history

Use this method if you want to fetch messages gradually. They are fetched in descending order (from newest to oldest) by default.

var history = myChannel.history(chunkSize: 50);

await history.more();
print(history.messages.length); // 50
await history.more();
print(history.messages.length); // 100

Using channel.messages

Use this method to fetch many messages at once.

var history = myChannel.messages(from: Timetoken(1234567890));

var count = await history.count();
print(count);

var messages = await history.fetch();
print(messages.length);

await history.delete(); // Beware! This will delete all messages matched

Multiple keysets

There are two ways to use multiple keysets at the same time, as follows:

Using named keysets

You can add multiple keysets with a name to an instance of PubNub.

pubnub.keysets.add(myKeyset1, name: 'keyset1');
pubnub.keysets.add(myKeyset2, name: 'keyset2');

To use a named keyset instead of the default, pass its name in a using: parameter into one of the pubnub instance methods:

pubnub.publish('channel', 42, using: 'keyset1');
var myChannel = pubnub.channel('channel', using: 'keyset2');

Using a keyset instance

Instead of adding the keyset to pubnub.keysets, you can use the keyset: named parameter to pass a keyset instance directly to pubnub instance methods:

pubnub.subscribe(channels: {'channel'}, keyset: myKeyset1)

Contributing

1. Clone the repository.

   git clone https://github.com/pubnub/dart.git

2. Enter the directory and install dependencies.

   cd dart
   pub get

3. Run the build_runner to generate necessary source files.

   pub run build_runner build