Go CQRS + Event Sourcing example application.
CQRS stands for Command and Query Responsibility Segregation, a pattern that separates read and update operations for a data store. Implementing CQRS in your application can maximize its performance, scalability, and security. The flexibility created by migrating to CQRS allows a system to better evolve over time and prevents update commands from causing merge conflicts at the domain level.
Event sourcing persists the state of a business entity such an Order or a Customer as a sequence of state-changing events. Whenever the state of a business entity changes, a new event is appended to the list of events. Since saving an event is a single operation, it is inherently atomic. The application reconstructs an entity’s current state by replaying the events.
Nice article on Event Sourcing. <a href="https://docs.microsoft.com/en-us/azure/architecture/patterns/cqrs"Aarticle on CQRS.
- Orders - service for order creation and retrieval
- Commands used for order creation and processing
- Queries used for orders retrieval
- Processor - dumb service which mocks order processing
- Command store - persists commands (MongoDB)
- Query store - consumes events from kafka commands channel and saves/updates data for queries (PostgreSQL)
- Kafka - used as communication level between Command-Query stores and Order-Processor services
cd /deploydocker-compose up -dcd ../go run cmd/processor/main.gogo run cmd/orders/main.go
After that you'l be able to run commands and queries.
curl --location --request POST '127.0.0.1:8080' \
--header 'Content-Type: application/json' \
--data-raw '{
"id": "someid",
"name": "somename",
"status": "new"
}'curl --location --request POST '127.0.0.1:8080/someid' --data-raw ''curl --location --request GET '127.0.0.1:8080'curl --location --request GET '127.0.0.1:8080/someid'