Opik Backend

Architecture

• Layered: Resource → Service → DAO (never skip layers)
• DI: Guice modules, constructor injection with @Inject
• Databases: MySQL (metadata, transactional) + ClickHouse (analytics, append-only)

Naming Conventions

Plural Names (Resources, Tests, URLs, DB Tables)

• Resource classes: TracesResource, SpansResource, DatasetsResource (not TraceResource)
• Resource test classes: TracesResourceTest, SpansResourceTest, DatasetsResourceTest (not TraceResourceTest)
• URL paths: /v1/private/traces, /v1/private/spans (not /v1/private/trace)
• DB table names: traces, spans, feedback_scores (not trace, span, feedback_score)

Singular Names (DAO, Service)

• DAO classes: TraceDAO, SpanDAO, DatasetDAO (not TracesDAO)
• Service classes: TraceService, SpanService, DatasetService (not TracesService)