14
[1] Notes on "Building Microservices"
Currently reading Building Microservices: Designing Fine-Grained Systems and trying to curate notes for myself and some greater good 😉. I'm trying to approach this in a minimalistic way keeping the essence of chapters intact.
- Cohesion - To have related code grouped together.
- Enforcing SRP by Uncle BOB
- Gather together those things that change for the same reason, and separate those things that change for different reasons.
-
Key rules
- Small enough and no smaller.
- Is it codebase too big to be managed by a small team?
- Golden rule: Can you make a change to a service and deploy it by itself without changing anything else?
- Decoupling is an important aspect
- Modelling the service right
- Choosing right good, decoupled APIs
- Performance improvement can be done easily by consuming a new stack
- Adopting new tech is easy - Start with a service with limited potential impact.
- Key : Bulkheads (Barriers between services)
- Service boundaries are obvious bulkheads
- In monolithic, everthing stops at once. We run it on multiple machines to handle this scenario.
- In microservices, building a system that handles total of failure of one service( and degrade functionality accordingly).
- Scaling is easier for micro than monolithic service. One aspect of complete service can be scaled individually.
- On-demand provisioning (like by AWS) on pieces that need it.
-
Key factors
- Delta in subsequent releases
- Avoiding High Risk, Large Impact deployments
- Microservices mitigates above factors' bad consequences
- Working on any one codebase to hit the sweet spot of team size and productivity.
- Reuse of existing functionality
- Web, native application, mobile web, tablet app, or wearable device
- Scary Legacy code - vital and risky to replace
- Small service - Low cost to replace
14