"Unlocking the Potential: Enhancing Scalability and Performance with Spring Microservices"

What are microservices?

Spring microservices refer to a way of designing and building software applications as a collection of small, loosely coupled services.

Microservices are independently developed, which means:

• A single developer or small team is responsible for a microservice.

• A microservice has its own code repository.

• We deploy microservices independently.

We divided amazon project in small module or services in this diagram

What is loosely coupled services?

Loosely coupled means services are independent so that changes in one service will not affect any other. For example i am working on order service and my other team is working on product services so whenever i apply my code changes and submit my code it will not reflect on other service.

Example: Amazon Shopping Microservices

For example if i want to build website so i breakdown services into small modules and i work on particular module so its easy to manage whole application developing.

Amazon microservices diagram shows how exactly its works

Project Structure Given Below

microservices-example/

├── product-service/

│ ├── src/

│ │ └── main/

│ │ └── java/

│ │ └── com/

│ │ └── example/

│ │ └── productservice/

│ │ ├── ProductServiceApplication.java

│ │ ├── controllers/

│ │ │ └── ProductController.java

│ │ ├── models/

│ │ │ └── Product.java

│ │ └── services/

│ │ └── ProductService.java

│ └── pom.xml

├── order-service/

│ ├── src/

│ │ └── main/

│ │ └── java/

│ │ └── com/

│ │ └── example/

│ │ └── orderservice/

│ │ ├── OrderServiceApplication.java

│ │ ├── controllers/

│ │ │ └── OrderController.java

│ │ ├── models/

│ │ │ └── Order.java

│ │ └── services/

│ │ └── OrderService.java

│ └── pom.xml

└── pom.xml

Key characteristics of Spring microservices

1. Service Independence: Each microservice is developed and deployed independently, allowing teams to work on different services without affecting each other.

2. Decentralized Data Management: Each microservice manages its own database or data store, which helps to prevent data coupling between services.

3. Resilience and Fault Tolerance: Microservices are designed to be resilient to failures, with each service being able to handle failures gracefully without affecting the entire system.

4. Scalability: Microservices can be scaled independently based on the demand for each service, allowing for more efficient resource utilization.

5. Service Discovery: Services can discover and communicate with each other dynamically, using tools like Eureka or Consul for service discovery and registration.

6. API Gateway: An API gateway can be used to route and manage requests to the appropriate microservice, providing a single entry point for clients.

Drawback or limitations of microservices

1. Increased Complexity: While microservices can simplify development by breaking down large applications into smaller, more manageable services, they can also introduce complexity. Managing a large number of services, each with its own codebase, deployment pipeline, and dependencies, can be challenging.

2. Network Latency: Communication between microservices typically occurs over the network, which can introduce latency compared to in-process calls in a monolithic architecture. This latency can impact overall system performance, especially in distributed environments.

3. Data Management: Microservices often have their own databases or data stores, which can make managing data consistency and transactions more complex. Implementing distributed transactions or maintaining data consistency without them can be challenging.

4. Operational Overhead: Managing a microservices architecture in production requires additional operational overhead compared to a monolithic architecture. You need to monitor, scale, and manage the lifecycle of each service independently, which can be resource-intensive.

5. Testing Complexity: Testing a microservices architecture can be complex due to the need to test interactions between services. End-to-end testing can be challenging, and you may need to use mock services or stubs to simulate dependencies.

6. Deployment Complexity: Deploying microservices can be more complex than deploying a monolithic application. You need to manage the deployment of multiple services, potentially using different technologies and versions, which can increase the risk of deployment failures.

7. Security Challenges: Securing microservices can be more challenging than securing a monolithic application. You need to consider security at the service level, as well as securing communication between services, which can introduce additional complexity.

Interview Questions on microservices topic.

Should we have a shared database in a microservice architecture? No, because a shared database equates to coupled microservices. Each business area should have its own database. Ideally, a database is used by one microservice.

What is an API gateway?

An API gateway is for your clients (web front ends, REST clients, etc.) to access microservices without needing to know microservice implementations.

The gateway acts as a facade to the back end, allowing us to make changes without breaking those clients.An API gateway is also a single point of access. The client doesn’t need to have a long list of microservices to call.

What should we be thinking of when designing microservices?

Microservices should be highly cohesive with each service should doing only one thing. A developer would want to build loosely coupled microservices with few dependencies between the microservices.

What is API Gateway and how its useful in microservices?

An API Gateway is a server that acts as an API front-end, receiving API requests from clients and routing them to the appropriate microservices. It often serves as an entry point for APIs and handles tasks such as routing, authentication, rate limiting, caching, and request/response transformations.

Here's a more detailed explanation of its key features and functions:

1. Routing: API Gateways can route requests to different backend services based on the request URL or other parameters. This allows clients to access multiple microservices through a single endpoint.

2. Authentication and Authorization: API Gateways can handle authentication and authorization for incoming requests. They can authenticate clients using API keys, OAuth tokens, or other mechanisms, and authorize access to specific resources based on the client's permissions.

3. Rate Limiting: API Gateways can enforce rate limits on incoming requests to prevent abuse and ensure fair usage of resources. They can limit the number of requests a client can make within a certain period of time.

4. Caching: API Gateways can cache responses from backend services to improve performance and reduce latency. They can cache responses based on request parameters and expiration times.

5. Request/Response Transformation: API Gateways can modify request and response payloads to meet the needs of clients and backend services. They can translate between different data formats, such as JSON and XML, and add or remove headers and other metadata.

6. Load Balancing: API Gateways can distribute incoming requests across multiple instances of a microservice to balance the load and ensure high availability and scalability.

7. Logging and Monitoring: API Gateways can log requests and responses for auditing and debugging purposes. They can also provide metrics and monitoring data to track the performance and health of the API.

8. Security: API Gateways can enhance the security of APIs by providing features such as encryption, tokenization, and content validation. They can protect APIs from common security threats, such as SQL injection and cross-site scripting (XSS) attacks.
   

In this diagram you can see how API Gateway is connected with all microservices