What is Microservices Architecture?

Microservices architecture is a method of constructing applications as a collection of small, self-contained components that interface. It’s like having a set of workers all working coordinately with a common agenda, each operating from a certain expertise. This is different from the previous monolithic structure, which is like having a single big shot doing everything, and as the application gains complexity, it is cumbersome to control.

Microservices architecture is different from traditional monolithic architecture in the following ways.

• Decentralization: Microservices take functionality and spread it across individual services, while monolith combines all functionality within a single codebase.
• Loose Coupling: Microservices communicate through APIs with high-level cohesion and low-level coupling, while in the case of monoliths, components are usually coupled and cohesive.
• Independent Deployment: Microservices allow the change-out or deployment of an individual service without downtime of the whole system, while changes within a monolithic architecture need deployment coordination.
• スケーラビリティ： Microservices can be adjusted independently based on user requirements while compared to approaches like monolithic, which requires scaling across the whole application.
• Fault Isolation: In microservices, when one service fails, it does not influence the rest of the services, whereas in monolithic services, the failure of one component may result in the failure of the entire application.

These are: 

メリット：

• スケーラビリティ： Develop certain services at a certain scale as per the demand so that the utilization of resources is efficient.
• 俊敏性の向上： Developing and deploying independently relates to faster cycle initiation and change responsiveness.
• Technology Flexibility: Select the suitability of technologies for each service to determine their potential to support innovation and service optimization
•  Fault Isolation: To reduce the impact of service failures and improve system stability.
•  Maintainability: Each small, specific service is easier to understand, develop, and manage than a single, all-encompassing service.

課題：

• Increased Complexity: Managing distributed systems requires a more intricate approach than centralized systems due to inherent complexities.
• Data Management: One of the difficulties of distributed data is controlling applications and maintaining data consistency across services.
• Testing: It is important to do all simple and complex testing to ensure compatibility of all the services and stability of the whole system after its deployment.
• コミュニケーション： Inter-service communication is crucial to efficient operation, but it brings latency and possible areas of failure.
• セキュリティ： Securing sensitive data across several services needs to be well-planned and executed to avoid service vulnerabilities.

Microservices mostly interact through APIs (Application Programming Interfaces), which describe how data will be exchanged and in what format. Such communication patterns include:

• Synchronous Request-Response: One service forwards a request to another service and expects the latter to respond. This is simple, but if not managed well, it may cause tight coupling and performance difficulties.
• Asynchronous Messaging: Services exchange messages through a message broker to count on decoupling and gain more scalability. This pattern is most effective when a large amount of data or events need to be processed.
• Event-Driven Architecture: Services publish events that other services can then listen to to foster loose coupling and responsiveness. This pattern aligns well with situations where updates or changes are required across multiple services.

Best practices include: 

• Domain-Driven Design (DDD): Decompose the system into a bounded context covering business capabilities that will enhance the system’s readability and maintainability.
• API-First Design:  Set up clear and well-documented interfaces where services must interoperate in the system to ensure consistency and ease of integration.
• Containerization:  Divide services into packages and put them into deployment containers for better control and easy scaling of solutions.
• Continuous Integration and Continuous Delivery (CI/CD):  Standardize build, test, and deployment with regular, predictable, and repeatable releases.
• Monitoring and Observability: Log and monitor service status and performance to ensure that they are well recorded and documented so that if there’s a problem, the root cause can be easily identified.

Real-life examples of successful microservices include:

• Netflix:  Implemented a microservices-based architecture to support global expansion and manage high traffic volumes for their streaming service.
• Amazon： The e-commerce site opted for microservices architecture after migrating from its previous monolithic design, aiming to improve adaptability and versatility.
•  Uber: Microservices manage ride requests, payments, and drivers separately, facilitating growth.

The above examples illustrate how microservices can potentially influence the creation and maintenance of large software systems, as well as their potential impact on user satisfaction.

It is important to remember that microservices are not a one-size-fits-all solution. Consider the specific needs and complications of your application before taking on this architectural style.