Microservice architecture is an architectural style that structures an application as a collection of loosely coupled services. Each service runs in its own processes and communicates through APIs. Microservices aim to overcome the limitations of monolithic architecture.
- Scalability: Since each service is independent, they can be scaled horizontally by adding more instances of that service. This makes it easy to scale individual components based on demand.
- Agility: Services are developed, deployed and scaled independently. Developers can quickly update or replace a service without affecting others. This results in rapid, independent development and release cycles.
- Fault isolation: Since each service has its own processes and resources, a failure in one service does not affect other services. This improves fault tolerance and reliability. The entire system does not have to be restarted for a single service failure.
- Polyglot persistence: Services are not restricted to any specific data store. They can use different databases and storage technologies based on their needs. This improves flexibility.
- Independence of teams: Since each service is independent, different teams can work on different services concurrently. This allows for separation of concerns and specialized teams.
- Define domain-driven services: Identify core business capabilities and create independent services around those domains. This results in high cohesion within services and loose coupling between services.
- Use lightweight protocols: Services should communicate using lightweight protocols like HTTP/RESTful APIs and message queues. This decouples services and makes them independently deployable.
- Deploy independently: Services should be packaged independently so they can be deployed, upgraded and scaled independently. They should be able to run on any environment or platform.
- Replicate non-functional requirements: Each service should be self-sufficient by replicating non-functional requirements like security, logging, monitoring, caching, etc.
- Use service discovery: A service discovery mechanism is required to dynamically find and register microservices. This allows services to locate each other at runtime.
- Plan for failure: Failures are inevitable in distributed systems. Plan for failure scenarios and implement retries, timeouts, circuit breakers, and fallback mechanisms.
- Increased complexity: Due to the distributed nature, microservices introduce operational complexity. Managing many independent services requires orchestration, discovery, monitoring, logging, etc.
- Orchestration challenges: Coordinating and choreographing interactions between independent services can be challenging. Service mesh architectures are emerging to simplify service orchestration.
- Testing issues: Testing interactions between independently deployed services is hard. Test strategies like contract testing, chaos testing, etc. are required.
- Debugging difficulties: Distributed tracing and logs correlation techniques are required to effectively debug microservices.
While microservice architecture brings many benefits, it also introduces operational challenges due to its distributed nature. A well-planned microservices implementation that addresses these challenges can provide an effective architecture for building scalable, modular applications.