Set B · 6 sheets
Where one module ends and the next begins, and how messages cross the line without losing anything.
B-01 Services & Boundaries
One deployable with walls the compiler enforces. Not a stage on the way to microservices, but a shape a system can stay in for a decade.
Drawn Feb 2011·Revised Apr 2025·6 min
B-02 Services & Boundaries
Find the seams with language, rate of change and team shape. Draw the context map first, and only then decide what deploys separately.
Drawn Mar 2015·Revised Jul 2025·6 min
B-03 Services & Boundaries
You cannot commit a row and publish a message in one transaction. Write the message to a table instead and let a relay carry it to the bus.
Drawn Nov 2019·Revised Mar 2026·5 min
B-04 Services & Boundaries
Two models, one database, no mediator. Separate the shapes you write from the shapes you read and stop there until something forces you further.
Drawn Aug 2017·Revised Dec 2025·6 min
B-05 Services & Boundaries
At-least-once means twice, eventually. Make the operation naturally repeatable, or let a unique constraint on an inbox table settle the argument.
Drawn Jan 2022·Revised Jun 2026·6 min
B-06 Services & Boundaries
The version is a promise to people you will never meet. Put it in the URL, keep changes additive, and treat a sunset date as a project rather than a header.
Drawn Jul 2023·Revised Oct 2025·6 min