What happens if @PostConstruct throws an exception?
What happens if @PostConstruct throws an exception? When a @PostConstruct method throws an exception in Spring, it is treated as a fatal bean initialization failure — and depending on where…
How do you detect bean initialization issues in large applications?
How do you detect bean initialization issues in large applications? Detecting bean initialization issues in large Spring applications is one of the most important real-world debugging skills — because most…
Why does a Spring Boot app consume more memory over time?
Why does a Spring Boot app consume more memory over time? 1. JVM Memory Model (Important Foundation) Spring Boot runs on the JVM, which manages memory automatically. Main JVM Memory…
RestClient in Spring Boot – Modern Alternative to RestTemplate
RestClient in Spring Boot – Modern Alternative to RestTemplate (Deep Dive into Fluent API, Internals & Interceptors) In the previous part, we understood why RestTemplate is no longer the best…
Synchronous Communication Between Microservices in Spring Boot
Synchronous Communication Between Microservices in Spring Boot (OrderService ↔ ProductService using RestTemplate & RestClient) In a real-world microservices architecture, services rarely live in isolation. They constantly need to talk to…
Role-Based Authorization in Spring Boot using @PreAuthorize and @PostAuthorize
Role-Based Authorization in Spring Boot using @PreAuthorize and @PostAuthorize In modern Spring Boot applications, security is not just about authentication (who you are) but also about authorization (what you…
OAuth 2.0 vs OIDC – Complete Guide with Stateless Spring Boot Implementation
OAuth 2.0 vs OIDC – Complete Guide with Stateless Spring Boot Implementation OAuth is one of the most misunderstood topics in security. Most developers use it daily (Google login,…
OAuth 2.0 – Complete Guide (High Level Design)
OAuth 2.0 – Complete Guide (High Level Design) What is OAuth 2.0? OAuth stands for Open Authorization. It is an authorization framework, not authentication. It allows: Secure third-party applications…
JWT Authentication in Spring Boot – Full Implementation Guide
JWT Authentication in Spring Boot – Full Implementation Guide We will implement: User Registration Token Generation (Login) JWT Validation Filter Custom Authentication Provider Secured APIs Refresh Token Step 1…
JWT (JSON Web Token) – Complete Notes
JWT (JSON Web Token) – Complete Notes What is JWT? JWT (JSON Web Token) is a stateless authentication mechanism used to securely transmit information between parties as a JSON…