What is a Message and a MessageChannel in Spring Integration?

Spring Integration

A Message is the fundamental unit of data flowing through an integration flow, consisting of a payload (the actual data) and headers (metadata key-value pairs, like a timestamp or correlation ID, that travel alongside the payload without being part of it). A MessageChannel is the pipe that decouples a message's producer from its consumer(s) — a PointToPointChannel delivers a message to exactly one of possibly several subscribed consumers, while a PublishSubscribeChannel broadcasts it to every subscriber.