Microservice

An independently deployable service owning one business capability and its data.

Problem it solves: Lets teams scale and deploy parts of a large system independently.

Where it sits: Called by other services or the gateway.

When to use

  • Clear domain boundaries and independent scaling or team ownership.

When not to use

  • Small teams or early products, where a modular monolith is simpler.

Failure modes

  • Network calls replace function calls: more latency and partial failure.
  • Distributed transactions become necessary.

Metrics to watch

  • Per-service SLO burn
  • Dependency latency (ms)

Alternatives

  • Modular monolith

Configuration in Labs (illustrative defaults)

  • Instances (count) = 2 — Identical copies behind this logical component. Capacity scales linearly in this model.
  • Capacity per instance (req/s) = 800 — Maximum requests one instance completes per second before it saturates.
  • Base service time (ms) = 15 — Processing time per request at zero load. Queueing adds to this as utilisation rises.

In the guide