Speaker: Pedro Assumpcáo | https://github.com/pedroassumpcao | @pedroassumpcao

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Event Sourcing and CQRS are application architecture patterns that commonly are used together to leverage an immutable event-centric model. Differently than the CRUD model where only the current state is mutated, Event Sourcing relies on a series of stored events to drive the business logic and to build the current state of the application.

The main advantages of Event Sourcing are:

• application design and business logic speak the same language;
• audit log for free with all the changes the system had;
• temporal queries, where is possible build the application state in any point in time.

In this talk, I will cover a quick Event Sourcing and CQRS introduction, but the main part is about FootBroker (https://footbroker.tk), an online soccer fantasy game that it is running in production in a beta stage, and has its main pieces using Event Sourcing and CQRS patterns.

Based on the game needs, I will present:

• what parts are using Event Sourcing and why?
• what parts are not using Event Sourcing and why?
• the main architecture components that use GenStage, GenServer, and GenStateMachine;
• code examples for commands, aggregates, events, event handlers, and projectors;
• examples of stored events and projections (application state);
• business edge cases and how those were implemented;

At the end of the talk, you should have a good practical understanding of Event Sourcing and CQRS and its pros and cons.

See you there.

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Pizza served at 6pm, talk will start at 6:15pm, please be on time.

We will greet you downstairs and send you up. Please do not be late as we cannot be downstairs once the meetup starts.

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