IMessengerCallback

IMessengerCallback is a contract used in software development to receive asynchronous events from a messaging subsystem. It is typically implemented by client components that need to react to messages, delivery updates, errors, and other real-time events within a messaging framework or application. Interfaces with names beginning with I are common in languages such as Java, C#, or Kotlin, and IMessengerCallback serves as a typed callback mechanism for decoupled event handling.

Commonly defined methods may include onMessageReceived(message), onMessageDelivered(message, timestamp), onMessageSeen(message, user), onDeliveryFailure(message, error), onTypingStatusChanged(user, isTyping), and onError(error). Specific APIs differ across libraries, but the general pattern is to expose a set of event handlers that the messenger core will invoke when relevant events occur.

Usage typically involves a component that can produce or distribute events registering an IMessengerCallback implementation. The messaging framework then calls the implemented methods asynchronously, often on a background thread or the user interface thread. Implementers should avoid long-running work inside callbacks, preferring to offload processing to background tasks, and should consider thread-safety and lifecycle management, such as unregistering the callback during shutdown or reconfiguration.

Contexts for IMessengerCallback include chat SDKs, real-time collaboration tools, and enterprise messaging platforms. While some ecosystems favor observers or futures/promises, the callback interface remains a common primitive for integrating with event-driven messaging components.

See also: Callback interface, Observer pattern, Messaging framework, Delivery receipt, Typing indicators.