architecture – Page 16 – Türker Yıldırım

The read model we built before anybody asked

NoteOctober 3, 20232 min read

A denormalised projection built for a dashboard that was specified, prioritised and then never scheduled. The projection was the right shape for a requirement that did not arrive,…

Quorum queues, and the mirroring we removed

NoteOctober 2, 20232 min read

Classic mirrored queues have been the deprecated way to get replication for a while, and the replacement has different failure behaviour worth understanding first. The throughput cost is…

A specification object, and when the indirection pays

NoteSeptember 23, 20232 min read

A rule about which orders are eligible for a discount, expressed three times: in a query, in a validation check and in a report. The two methods must…

A repository interface, one implementation, one fake

NoteSeptember 21, 20232 min read

The argument that an interface with one implementation is waste ignores that the test double is a second implementation, and the argument that the double justifies it ignores…

Import blocks, and the resources we had been pretending to manage

Deep diveSeptember 21, 202310 min read

Terraform 1.5 in June, and an import that is part of the plan rather than a side effect. Fourteen resources created by hand in 2019.

A value object library, and the day it needed a serializer

Deep diveSeptember 20, 202310 min read

A Money type, an Email type, and thirty more, none of which can cross a boundary without being unwrapped by hand.

An outbox, and the publisher we removed from the transaction

Deep diveSeptember 20, 202310 min read

An order committed and an event never published, twice in one week. A broker call inside a database transaction, and a rollback after it.

A JSON column that had become a schema

Deep diveSeptember 20, 20239 min read

A settings column with forty keys, four of which are queried, and a WHERE on a JSON path scanning two million rows.

A saga in a table, because the alternative was a framework

NoteSeptember 5, 20232 min read

A three-step process across two external systems, needing compensation when step two fails, and no appetite for a workflow engine. A state machine in a table, advanced by…

Deciding not to split a service, and writing down why

NoteAugust 29, 20232 min read

The reporting module is slow, memory-hungry and occasionally takes the application down, which is a real argument for extracting it and not a sufficient one. The revisit condition…