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Choose a Path

Protean supports three architectural approaches to building applications. Rather than forcing a single pattern, it lets you pick the right level of sophistication for your domain — and evolve over time as your needs change.

Each approach builds on the one before it, so the concepts you learn at one level carry forward to the next:

  1. Domain-Driven Design — Model your domain with aggregates, application services, and repositories. Events propagate side effects. This is the foundation.

  2. CQRS — Separate reads from writes with explicit commands, command handlers, and read-optimized projections. Builds on everything in DDD.

  3. Event Sourcing — Derive state from event replay instead of storing snapshots. Adds full audit trails and temporal queries. Builds on everything in CQRS.

Not sure which to pick?

Start with DDD. It's the simplest path and covers the majority of use cases. You can always evolve to CQRS or Event Sourcing later — Protean is designed to make that transition smooth. See the Architecture Decision guide for a systematic framework.

How These Pathways Work

Each pathway page gives you:

  • A brief overview of the architectural approach
  • A diagram of the request flow
  • The specific Protean elements you'll use
  • A guided reading order through the existing documentation

The pathway pages are not standalone tutorials — they orient you and then point you to the detailed guides for each concept. Think of them as a curated reading list tailored to your chosen architecture.