• CQRS separation of orders:

• Command/query handlers for IPC,

• Storing query responsibility in Redis

• Storing command responsibility in Postgres

• Synchronizing both responsibilities using RabbitMQ and domain events

• Clean architecture:

• Principles of SOLID

• RSP (Reuse/Release Equivalence Principles)

• Precise division of layers:

Domain - layer that serves as implementation of critical business rules, is a core and has no dependencies on anything except of itself;

Application - layer that serves as implementation of application business rules, invokes critical (domain) business rules and defines interfaces to implement in infrastructure layer;

Infrastructure - layer of driven (secondary) adapters, which wrap around a tool (db, message bus, etc.) and adapt it's I/O to a port, which fits the Application layer needs;

Presentation - layer of driving (primary) adapters, which wrap around a use case and adapt it's I/O to a delivery mechanism (HTTP/HTML, HTTP/JSON, gRPC/Protocol Buffers, etc.).