Spring Data JPA is a high-level data access framework within the Spring ecosystem designed to dramatically reduce boilerplate code when interacting with relational databases. Acting as an abstraction layer on top of the Java Persistence API (JPA) and an underlying ORM (Object-Relational Mapping) provider, it allows developers to implement data access layers simply by declaring […]
Spring Boot connects to a relational database by reading spring.datasource.* settings and building a DataSource, which is a pool of ready connections (HikariCP by default). JdbcTemplate sits on top of that DataSource and runs plain SQL for you, handling connections, statements, result sets, and cleanup. The four basic operations are INSERT (create), SELECT (read), UPDATE
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A bean is an object that the Spring IoC container creates, configures, and manages for you, instead of you calling new. Spring finds beans by scanning for stereotype annotations (@Component, @Service, @Repository, @RestController) or by reading @Bean methods in a @Configuration class. It wires them together with dependency injection, so the Controller gets the Service
Metrics are numbers that describe how an application behaves while it runs, such as memory used, CPU load, request counts and response times. They are used to spot slow or overloaded applications, plan capacity and raise alerts before users notice a problem. Spring Boot Actuator collects JVM, system, web and database metrics automatically through Micrometer,
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Health monitoring means checking, through a URL, whether an application and the systems it depends on are working. It is used so that monitoring tools, load balancers and Kubernetes can detect a failing application automatically and react, for example by restarting it or stopping traffic to it. Spring Boot Actuator provides /actuator/health, which combines the
Actuator is a Spring Boot module that exposes operational information about a running application through ready-made HTTP endpoints. It is used to monitor and troubleshoot an application: is it up, is the database connected, how much memory is used, which URLs and beans exist. You add one dependency (spring-boot-starter-actuator) and the endpoints appear under /actuator,
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Swagger UI is an interactive web page that displays your REST API and lets you call it directly from the browser. It is used so that developers and testers can explore endpoints, send real requests and see real responses without Postman. It reads the OpenAPI document (/v3/api-docs) and builds a clickable page from it automatically.
OpenAPI is a standard, language-neutral format that formally describes a REST API: its URLs, methods, request bodies, responses and status codes. It is used so that developers, testers and client teams can understand and try an API without reading the source code. In Spring Boot, the springdoc library scans your controllers and generates the OpenAPI
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API Documentation in Spring Boot refers to the automated generation, structuring, and presentation of machine-readable and human-friendly descriptions for RESTful web services. Rather than manually writing and maintaining static documentation files—which quickly become outdated as endpoints evolve—Spring Boot leverages open standards and tools (primarily via libraries like Springdoc-OpenAPI) to inspect controllers, models, and annotations at
Integration testing checks that several application layers work correctly together as one workflow. It is used to catch problems that unit tests miss, such as wrong wiring, wrong JSON mapping or a query that doesn’t match the service logic. Here a request goes through Controller, Service and Repository into a real MySQL test database, and
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