Slides for my "Introduction to Event Sourcing and CQRS" session at the IASA-IL meeting. Abstract: Event sourcing is a pattern for modeling the application’s business logic. It states that all changes to application state should be defined and stored as a sequence of events. Its advantages are many: * Gives freedom to refactor the business logic, allowing better response to new requirements. * Suitable for building scalable, highly concurrent, distributed systems. * Stored events give the true history of a system, which is required by law in some industries. * The system’s state can be reversed to any point in the past for retroactive debugging. * The required infrastructure is simple - no monstrous databases are involved. Vladik will also describe CQRS, an architecture that goes hand in hand with Event Sourcing.