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Event Sourcing

Definition​

Event Sourcing is an architectural pattern where all changes to application state are stored as a sequence of events. Instead of storing just the current state of the data, event sourcing captures all changes as discrete event objects, providing a complete historical record.

Usage in Roll Claw​

In Roll Claw, event sourcing is a fundamental architectural approach that enables:

  • Complete historical reconstruction of any cat's timeline
  • Reliable offline operation with eventual consistency
  • Powerful historical analysis capabilities
  • Clear separation between commands (actions) and read models (views)

Technical Implementation​

In the Roll Claw system:

  1. All changes are recorded as immutable events
  2. Events are stored in an append-only store
  3. Current state is derived by replaying events
  4. Event streams can be processed to create various projections optimized for specific queries

Examples of Events in Roll Claw​

  • CatSightingRecorded
  • HealthStatusUpdated
  • TNRStatusChanged
  • TaskCompletedEvent
  • DisappearanceEvent

Benefits for Colony Management​

Event sourcing provides critical benefits for feral cat colony management:

  • Complete historical record of all cats and activities
  • Ability to work offline in the field and synchronize later
  • Rich historical analysis to identify patterns and issues
  • Reliable audit trail for all actions