wtf is moosehead?

Moosehead is a registration system built for JavaZone workshops and similar events. It's the backbone that handles sign-ups, registrations, and event management for conferences and workshops. At its core, the system works like a detailed record-keeper. Instead of just storing the current state of a registration (like "Alice is signed up"), it records every action that happens, someone signs up, someone cancels, a spot opens up. This approach, called event sourcing, means the system never loses track of what happened. It stores every single event in an event store, which is like a permanent ledger. When the system starts up, it replays all those recorded events to rebuild what the current state should be. The system is organized around two main concepts. Aggregates are responsible for handling commands, requests to do something, like "register person for workshop A." When a command comes in, an aggregate creates an event (like "person registered") and gives it a unique, incrementing revision number so nothing gets out of order. The eventstore then saves all these events permanently and can replay them whenever needed. This design means the system can always reconstruct exactly what happened, when, and in what order. A team running JavaZone workshops would use this to manage who's registered for which workshop, handle cancellations, track availability, and maintain a complete audit trail of all registration activity. Because every change is recorded as an event, organizers can see the full history of what happened and recover from mistakes without losing data. This kind of event-based system is particularly useful for complex registration scenarios where you need to track state changes carefully and ensure nothing slips through the cracks.