マイクロサービスアーキテクチャ入門

Welcome to the world of microservices! This architecture breaks down a large application into smaller, independent services.

Each microservice focuses on a single business capability and runs in its own process. Think of it like a team of specialists, each handling a specific job.

Before microservices, many applications were built as monoliths. A monolithic application is a single, tightly coupled unit where all components (UI, business logic, data access) are bundled together.

While simpler to start, monoliths can become complex, slow down development, and be harder to scale as they grow.

Let's compare:

• Monolith: Single codebase, shared database, deployed as one unit.
• Microservices: Multiple, small codebases; often independent databases; deployed individually.

The core idea of microservices is to achieve greater agility and scalability by decoupling concerns.

One major advantage of microservices is independent scalability. If your user authentication service is under heavy load, you can scale *only* that service, not the entire application.

This means more efficient resource usage and better performance for your users.

With microservices, small teams can work on individual services independently. This leads to faster development cycles and quicker releases.

Each service can be deployed on its own schedule, reducing the risk and coordination overhead associated with large, monolithic deployments.

Microservices allow for technology diversity. You can choose the best programming language or database for each specific service, rather than being locked into one stack.

They also offer increased resilience. If one service fails, the entire application doesn't necessarily crash. Other services can continue to function.

While powerful, microservices introduce operational complexity. You now manage many services instead of one, leading to challenges in:

• Monitoring & Logging
• Debugging across services
• Deployment pipelines

This requires robust infrastructure and DevOps practices.

Data consistency becomes harder. Each service typically owns its data, so ensuring data is consistent across multiple services can be tricky.

Inter-service communication also needs careful design. Services need to talk to each other reliably, whether through synchronous (like HTTP/REST) or asynchronous (like message queues) methods.

A key design principle is identifying Bounded Contexts. This concept, from Domain-Driven Design, helps define clear boundaries for each service.

Each bounded context represents a specific domain area with its own model and language. For example, a 'User Management' service has a clear boundary separate from an 'Order Processing' service.

When designing, think about service decomposition. How do you break down your application into meaningful, independent services?

• By business capability (e.g., Inventory, Payments)
• By sub-domain (e.g., Shipping, Billing)
• By team structure (Conway's Law)

Start with a few core services and iterate.

Which of the following are common benefits of using a microservices architecture?

Today, you learned about microservices architecture. We covered:

• How microservices differ from traditional monoliths.
• Key benefits like independent scalability, faster deployments, and tech diversity.
• Challenges such as increased complexity and distributed data management.
• Initial design thoughts like Bounded Contexts and service decomposition.

Next, we'll dive into how to actually build these services!