Events and notifications are crucial components in distributed systems, enabling communication and coordination among different parts of the system.
Events in Distributed Systems
An event is any significant occurrence or change in the state of a system or its environment. Events can be generated by hardware, software, users, or even external systems.
Types of Events:
- Hardware Events: Changes in hardware states like a printer getting connected or disconnected.
- Software Events: Changes within software applications, like a user logging in or a file being modified.
- User Events: Actions taken by users, such as clicking a button or submitting a form.
- System Events: Changes in the state of the system itself, such as a node failure or recovery in a cluster.
Notification in Distributed System
Notifications are messages sent to inform a system or user about an event that has occurred. They ensure that the relevant components are aware of changes and can respond accordingly.
Notification Mechanisms:
- Push Notifications: The system actively sends notifications to subscribers when an event occurs.
- Pull Notifications: Subscribers periodically check the system for new events.
- Publish/Subscribe Model: Components can publish events, and other components can subscribe to receive notifications about these events.