Event-Driven Architecture.

Designing systems around event production, detection, and reaction. Covers 8 sub-skills.

• Event-Driven Architecture · 1 of 3

  Event Sourcing Patterns

  Comparing event sourcing with classic CRUD on a relational table, what is the defining storage difference?

  AStores entities as documents in a normalised graph of foreign-key edgesBKeeps the latest row plus a denormalised audit shadow table beside itCPersists an append-only sequence of immutable state-change factsDSaves only the latest row of each entity, overwriting it on every change

• Event-Driven Architecture · 2 of 3

  Event Sourcing Patterns

  What is "checkpointing" in the context of event projection rebuilding?

  AMarking events as processed by deleting them out of the streamBStoring the last processed position so a failed rebuild resumes thereCTaking a database backup after each batch of events is projectedDCreating a hash of the current projection state for integrity checking

• Event-Driven Architecture · 3 of 3

  Event Sourcing Patterns

  Comparing the transactional outbox with publishing to the bus inside the domain DB transaction, what failure mode does the outbox specifically defuse?

  AA poison message that the broker keeps redelivering until handler crashBTwo consumers handling the same delivered message at the same timeCConsumers lagging because the read model rebuild is bottleneckedDDB commit succeeds but broker publish fails, leaving consumers blind