README

Heavily inspired by EventCentric.Core event sourcing framework.

How does it work

Example is a simplified case of bank accounts with two basic actions: Deposit and Withdraw to increase and decrease balance.

There is also a composite process - Transfer to show how sagas/process managers can be implemented.

Account is a aggregate root, a class that is subject to actions from commands,
each action that has effect on Account will create at least one DomainEvent instance, describing what happened, eg. MoneyWereDepositedEvent which says that some amount of money were deposited on Account
Account stores those events in order of occurrence,
UnitOfWork tracks events in Account, and when it is committed - all new events will be sent to EventStore,
EventStore will store new events as EventStream - an immutable list of changes for this account.
when new action occurs, UnitOfWork will reconstitute Account from stored events,
when ever event is stored, event emitter sends it to all presenters so they can react to it,
presenters AccountHistoryPresenter and AccountBalancePresenter subscribe to events and update data for read models, eg. as reaction to MoneyWereDepositedEvent, AccountHistoryPresenter will add new entry that says when and what amount was deposited. AccountBalancePresenter will increase accounts balance.

Example uses Tactician for command bus and Event Dispatcher for emitting events, but they can be replaced with anything else.