Pub/Sub messaging is a common pattern where publishers (senders of a message) and subscribers (recipients) communicate without knowledge of each other through a separate message brokering mechanism. Messaging is a great fit for applications requiring broadcast of important information and data updates, synchronization of context in games, trading systems, and chat applications. Backendless provides the APIs and the message routing/brokering functionality for receiving messages from publishers, processing them and subsequently delivering to subscribers. The system supports message filtering and conditional message delivery using subtopics and query-based subscriptions. Additionally, developers can override the default message routing algorithm with custom business logic.