PubSub Class Methods - Flutter

publish()

• publish() is used to publish messages on a specified topic in the room.

Parameters

• topic

  • type: String
  • This is the name of the topic, for which message will be published.

• message

  • type: String
  • This is the actual message.

• options

  • type: PubSubPublishOptions
  • This specifies the options for publish.

• payload

  • type: Map<String,dynamic>
  • If you need to include additional information along with a message, you can pass here as Map<String, dynamic>. This is optional parameter.

Returns

• Future<void>

Example

// Publishing message
room.pubSub
    .publish(
      "CHAT",
      "Hii",
      const PubSubPublishOptions(persist: true),
    );

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subscribe()

• subscribe() is used to subscribe a particular topic to get all the messages of that particular topic in the room.

Parameters

• topic:

  • type: String
  • Participants can listen to messages on that particular topic.

• messageHandler:

  • type: Function(PubSubMessage)
  • This function will be called, whenever pubsub message received.

Returns

• Future<PubSubMessages>

Example

// Subscribing 'CHAT' Topic

void handleMessage(PubSubMessage pubsubMessage) {
  print(pubsubMessage.message);
}

void subscribePubSubTopic() async {
  PubSubMessages pubsubMessages =
      room.pubSub.subscribe("CHAT", handleMessage);

  // do something
}

subscribePubSubTopic();

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unsubscribe()

• unsubscribe() is used to unsubscribe a particular topic on which you have subscribed priviously.

Parameters

• topic:

  • type: String
  • This is the name of the topic to be unsubscribed.

• messageHandler:

  • type: Function(PubSubMessage)
  • This is the message handler to be unsubscribed.

Returns

• Future<void>

Example

// Unsubscribing 'CHAT' topic
room.pubSub.unsubscribe("CHAT", handleMessage);