Module 3: Domain-Driven Design & Bounded Contexts: Guided Labs

Lab 1: Event-Storming Session

Map domain events, commands, actors, policies, hotspots, and external systems for a real workflow. Preserve disagreements instead of smoothing them over. Cluster events into candidate boundaries and state the evidence for each boundary.

Lab 2: Context Map and Language Test

Create a context map with upstream/downstream direction and relationship type. Build a glossary per context. Find three overloaded terms and show why one shared model would be harmful.

Lab 3: Aggregate Invariant Harness

Implement one aggregate with command methods and invariant tests. Attempt to put a second context’s state inside it, then refactor to asynchronous coordination with explicit intermediate states.

Lab 4: Anti-Corruption Layer

Translate a hostile legacy or partner schema into the domain model. Test unknown codes, missing fields, version drift, and partial failure. Keep external types out of the core package.

Evidence: event map, context map, glossary, invariant tests, and translation contract tests.

Executable core and integration limits

Use the domain extension for Labs 3–4. Its pure transitions and adapter tests do not replace repository conflict, asynchronous intermediate-state or partial-failure evidence. Complete DD1–DD6 alongside the original discovery artifacts.