Serverless Event Sourcing and CQRS with Next.js and Upstash

Microservices have become increasingly significant in software architecture, particularly with the rise of serverless technologies that allow for granular deployments. Event sourcing and command query responsibility segregation (CQRS) are architectural patterns that enhance the functionality of microservices. Event sourcing involves treating all system operations as events stored in an event store, allowing the recreation of internal states without data deletion. CQRS separates data models for commands (write operations) and queries (read operations), offering greater flexibility and simplifying event sourcing integration. The discussed system exemplifies these patterns through a serverless to-do list application, utilizing Upstash services such as Upstash Kafka for event storage, Upstash Redis for projection storage, and QStash for service notifications. Implemented with Next.js and Apollo GraphQL, this architecture enables scalable, flexible, and reliable data management. The system's architecture allows for asynchronous data processing and state calculation, ensuring that new events update the system state without direct client interaction.