This article explores when to use a microservice, when not to use and the pros and cons of using a microservices based architecture. As software systems grow more complex, architects and developers face a key decision: Should we build a monolith or implement a microservices based architecture ? In this post, we dive deep into microservices architecture, compare it to the traditional monolith, and help you decide when (and when not) to use it. This guide will help you in making the decision to go either way.

Monolithic vs Microservices: The Fundamentals

What is a Monolithic Architecture?

A monolith is a single, large software application where all the components are tightly coupled and run as one process.

Example: A simple e-commerce platform might have:

• Product catalog
• User management
• Shopping cart
• Payment processing
• Order processing
• Reporting

In a monolithic app, all of these components live inside the same codebase and deploy together and most of them will be developed in the same programming language and framework.

Block Diagram – Monolith:

In a monolith application , all services share the same database. Hence it is difficult to do database changes without impacting all services. Changes are propagated gloablly and no scope to make changes in isolation.

What is Microservices Architecture?

Microservices break down an application into smaller, independent services. Each service is responsible for a specific business function, communicates over APIs (usually HTTP or messaging), and has its own database.

Example: Using the same e-commerce example:

• Order Service
• Inventory Service
• Product Service
• User Service
• Payment Service
• Reporting Service

Each of these runs in its own process and can be deployed independently. Each service can be developed using a programming language and framework most suitable for that business purpose. For example the Order Service can be developed in Java and Spring boot where as the Reporting Service can be developed using python.

Block Diagram – Microservices:

In a microservices based architecture, each service has its own database.

Advantages of Microservices

• 1. High Scalability – Easy to Scale each service independently.
• 2. Independent Deployments – Each team can deploy their own services. Deployment frequency can fine tuned for each service independently.
• 3. Technology Diversity – Use different tech stacks per service.
• 4. Resilience – Failure of one service doesn’t result in crashing the entire app.
• 5. Faster Development & Deployment – Small, focused teams can make changes quickly and rollout features at a faster pace.
• 6. Better change management
• 7. Better security management – As services are isolated, a breach in one doesn’t necessarily affect other services.

Disadvantages of Microservices

• More Complex- More services = more moving parts.
• Data Management Challenges – Eventual consistency issues.
• Network Latency & Failure – More inter-service communication risks. Orchestration challenges.
• DevOps Demands – Requires mature tooling and processes.
• Tracing and debugging

When to Use Microservices

✅ Use when:

• Application is growing rapidly in complexity or scale.
• Multiple dev teams working independently across business units, functions.
• There is a need to scale parts of the system differently. For example a product listing service may need more scalability than a order processing service.
• Faster release cycles and rapid relase of business functions by leveraging independent service deployments and release schedules.
• When building cloud-native systems.

When NOT to Use Microservices

❌ Avoid if:

• The team size is small team or it is an early-stage startup ( easier and faster to do minimum viable product using monoliths).
• System is simple and doesn’t need high scalability.
• There is a lack of Devops infrastructure and team in place
• Need faster development cycles – This is not true always and varies from application to application.

Real-World Example

Netflix originally started as a monolith but migrated to microservices to handle massive load and a diverse device ecosystem. Now, hundreds of microservices manage user profiles, recommendations, streaming, and more.

Tools & Technologies – Microservices

• API Gateway: NGINX, Kong, AWS API Gateway
• Communication: REST, gRPC, Kafka, RabbitMQ
• Containerization: Docker
• Orchestration: Kubernetes
• Monitoring: Prometheus, Grafana
• Service Discovery: Consul, Eureka

Conclusion

Overall it is better to go with microservices if you are building an application that is intended for a larger audience and has high scalability needs.