Backendless features a powerful publish/subscribe (pub/sub) messaging system with easy-to-use APIs. A pub/sub implementation is a means of exchanging messages that consists of three components: publishers, subscribers, and a message broker (which in our case is Backendless). Your app can subscribe to receive messages using the Subscription API, and thus becomes a “Subscriber”. Publishers send messages to the message queue using the Publishing API, and the backend delivers messages to subscribers. Message delivery can be unconditional, where all messages are delivered to subscribers, or conditional, where realtime messages are only delivered if they match the subscription criteria. Backendless supports broadcasts, which deliver messages to multiple recipients, and point-to-point messaging, where a message is delivered to a single recipient.