#kafka
3 posts filed under this tag.
Auditing a Scala Service Against Chad Fowler's Four Regenerative Constraints
I walked a Scala order-processing service from my notes through Chad Fowler's four regenerative constraints. Two passed for free, two would force a real redesign. Here is what I learned about where "loosely coupled module" ends and "regenerative component" begins, and which parts of the redesign I would actually pay for.
Event-Log-as-Source-of-Truth Turns Schema Evolution Into a Forever Problem
When the log is the source of truth, every schema change is permanent. A Kotlin/Avro walkthrough of the rename that passed the Schema Registry check and silently corrupted every old event, plus the Protobuf and Avro invariants I now keep pinned above my desk.
The Transactional Outbox Is Not a Queue
The transactional outbox is a ledger, not a queue. Treating it like one is what breaks Postgres under load. This post walks through the specific failure modes — autovacuum stalls, xmin horizon drift, replication slot lag, poison pills — and the operational rules that actually keep it working in production.