Programming Tutorials

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Let's connect a Vert.x Web application to a CAS server. We'll use the vertx-pac4j library to add three handlers to our router: SecurityHandler, Callba

In the previous post, I explored what happens when my Kubernetes operator fails. I created a real failure by removing ConfigMap creation permission f

An unchanged Java app can stop building because a number inside its generated Xcode project is now too low. No new API call, no changed screen, just

A delivery attempt fails because the recipient is unavailable. The operations team now has to decide what to try next: confirm another delivery time,

Distributed Tracing: Making Microservices Observable Introduction Distributed Tracing is the superpower you need to debug micros

You write System.out.println("Hello World"); and hit Run. Something happens. Text appears on your screen. You smile. You move on. But have you ever

Java Card powers billions of SIM and bank cards using a highly stripped-down JVM designed for battery-less microcontrollers. By flipping traditional m

Ask an AI coding assistant to fix a bug in one file, and there's a decent chance it patches the symptom at the call site rather than the logic several

Cronflower: Turn a Spring Boot app into a distributed cron cluster @Scheduled is fine until it isn't. It runs in one JVM, so the moment you

Cronflower: Run a DAG workflow across your cluster, instead of chaining cron jobs Every team ends up here. One cron job at 02:00 charges th

Hi everyone! We recently worked on SafeTrack for a hackathon. It focuses on affordable autonomous navigation using smartphone sensors and real-time co

Tired of wrestling with Word file parsing while building Java collaboration tools? You can now edit DOCX files directly through a simple REST call. T

Introduction You've seen the tutorial. A @PostMapping endpoint, a MultipartFile parameter, a call to transferTo(). Done in five minutes. Wo

I used to think of API compatibility as a property of a diff: compare the old contract with the new one, classify the change, and move on. That works

The dangerous part of removing an API field isn't the diff. It's knowing who still depends on it. I built API Sentinel around that problem: instead

In Javalin, we define routes and add handlers around them. So where should SAML authentication go? In a handler that runs before the protected route.

Spring Boot's Quiet Hook for Shipping Configuration: EnvironmentPostProcessor Hi everyone! This is Mikhail Polivakha, technical lead of the

Ever been asked to add "just one more custom rule" to your application, only to watch your elegant logic turn into a massive, fragile switch statement