Well-Designed Microservices Architecture – Components List

1️⃣ Client Layer

Web UI (Browser)
Mobile App
API Clients (Postman, internal services)

2️⃣ API Access Layer

API Gateway

Request routing
Authentication & authorization
Rate limiting
API versioning
Request/response transformation

3️⃣ Identity & Security

Authentication Service
Authorization Service
OAuth2 / OpenID Connect
JWT / Token Service
Secrets Management (Vault, KMS)

4️⃣ Microservices Layer (Core Business)

Each service typically has:

Controller (REST)
Service layer (business logic)
Repository / DAO
DTOs
Validation
Local transactions

Examples:

Account Service
Customer Service
Order Service
Payment Service
Notification Service

5️⃣ Service-to-Service Communication

REST (HTTP/JSON)
gRPC
Messaging (Kafka / RabbitMQ)
Event-driven communication

Supporting components:

Message broker
Schema registry (for events)

6️⃣ Data Layer (Per Service)

Dedicated database per service
- RDBMS (PostgreSQL, MySQL)
- NoSQL (MongoDB, Cassandra)
Cache (Redis)
Search engine (Elasticsearch)

Rule: One database per microservice (logical ownership).

7️⃣ Transaction & Consistency

Local ACID transactions
Eventual consistency
Saga pattern
Compensating transactions
Idempotency handling

8️⃣ Service Discovery & Configuration

Service Registry (Discovery)
Centralized Configuration Server
Dynamic configuration refresh
Feature flags

9️⃣ Resilience & Fault Tolerance

Circuit breakers
Retries
Timeouts
Bulkheads
Rate limiting
Fallback mechanisms

🔟 Observability & Monitoring

Centralized logging
Distributed tracing
Metrics collection
Health checks
Alerting & dashboards

1️⃣1️⃣ Deployment & Runtime Platform

Containerization (Docker)
Container orchestration (Kubernetes)
Load balancers
Ingress controllers

1️⃣2️⃣ CI / CD & DevOps

Source control (Git)
Build pipelines
Automated testing
Artifact repositories
Deployment automation
Rollback strategies

1️⃣3️⃣ Data & Integration Support

ETL / Data pipelines
Reporting services
Batch jobs
Scheduled jobs

1️⃣4️⃣ Governance & Compliance (Enterprise)

Audit logging
Compliance checks
API governance
Version control & deprecation policies

In Reality

Small system → use fewer components
Large / banking system → most of these exist
Microservices ≠ using everything

Architecture evolves with scale and team maturity.

A well-designed microservices architecture includes API gateway, independent services with their own data stores, service communication mechanisms, resilience patterns, observability, centralized configuration, and automated deployment infrastructure.