Architecture Patterns: Monolithic Architecture vs Microservices Architecture

Monolithic Architecture

In Monolithic Architecture everything is tightly coupled (UI, Business logic and database schema)?together.

Advantages

• Simplicity in development: Monolithic Architecture offers simplicity in the development process. Since the whole application is built as one unit and developers can work within a unified codebase.
• Simplicity in testing: test cas es can be designed to cover an entire application without the need for integration testing for separated ser- vices.
• Easy Deployment: the entire application can be deployed as a single unit.

Disadvantages

• Scalability: To scale applications, the entire application must be replicated.
• Deployment: To deploy small changes, the entire application must be deployed and that may effect on deployment speed.
• Reliability: the entire application can be affected by a single failure.

Use cases

Monolithic architecture is well suited for small applications that don't require high scalability.

Microservices Architecture

In Microservices Architecture the entire application is divided into small loosely coupled services.

Communication

Services communicate with each other

Synchronous: using API calls or gRPC but this type of communic ation makes services dependant on each other and if one service is down the dependent service on it works incorrectly and the performance of this type of communication is slow down.

Asynchronous: using message brokers (RabbitMQ, Kafka, ActiveMQ...) and this type of communication makes services independent of each other.

Scalability

In Microservices Architecture each service can be scalable independent other services.

Deployment

In Microservices Architecture each service can be deployed independent other services.

Data layer

Database per service: each service has its own database and in this option each service works independently and if one service down other services work correctly but in this option has challenges in making distributed transactions and ensuring consistency of data between services,

Shared Database: there is one database shared between services and In this option making trans- actions is simple but this makes scaling is limited.

Development

In Microservices Architecture each service can be developed with a different technology stack and this adds more flexibility but makes development slow and complex.