Yash DabhadeAI Engineer

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Building Microservices

Sam Newman · Engineering

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Takeaways

Microservices are about independent deployability, not small codebases. The book is at its best when it tells you not to use microservices yet.

The Core Ideas

  • Model services around business capabilities (bounded contexts), not technical layers.
  • Information hiding: a service owns its data. A shared database is a distributed monolith waiting to happen.
  • Independent deployability is the goal. If you have to release five services together, you have not gained anything.
  • Start with a monolith when the domain is unclear. Split along seams once you understand them.

Migrating: Strangler Fig

  1. monolith
  2. put a proxy in front
  3. route one capability to a new service
  4. repeat
  5. monolith shrinks away
Incremental and reversible — you never have a big-bang cutover.

Distributed Transactions

Sagas instead of two-phase commit: a sequence of local transactions with compensating actions if a later step fails. Changed how I think about multi-step agent workflows too — every tool call is a step you might need to undo.