Several applications communicate with one another using events. If event-based communication happens from using messages, then event message patterns are used. The event message pattern is depicted in the following diagram:
In an event message pattern, if the subject has to announce an event, it will first create an event object. This object is then wrapped in a message and sent on a channel. The observer will receive the event from the channel and process it. Messaging in events does not alter the event notification; it just ensures that the notification reaches the observer.
