[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.

Introduction

Small, and Focused on Doing One Thing Well

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?

Autonomous : Freedom to govern itself

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

Key benefits

Tech Heterogenity

Performance improvement can be done easily by consuming a new stack

Adopting new tech is easy - Start with a service with limited potential impact.

Resilience : Capacity to recover quickly

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).

Scalability

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.

Easy of deployment

Key factors

• Delta in subsequent releases
• Avoiding High Risk, Large Impact deployments

Microservices mitigates above factors' bad consequences

Organizational Alignment

Working on any one codebase to hit the sweet spot of team size and productivity.

Composability

Reuse of existing functionality

Web, native application, mobile web, tablet app, or wearable device

Replacibility optimization

Scary Legacy code - vital and risky to replace

Small service - Low cost to replace