Java | Matheus Oliveira

Trace waterfall of a single request: one fast root span above a descending ladder of forty identical SELECT queries

Observability in Practice: Why Instrument, and How Quarkus Makes It Cheap

Part 1 of 2. Why observability became the market standard after OpenTelemetry graduated from the CNCF, the minimum vocabulary to follow along, and what Quarkus gives you without writing a line of code.

Kafka Integration in Quarkus: Reactive Messaging, @Incoming and @Outgoing

Take messaging outside the application with SmallRye Reactive Messaging. Channels vs Topics, @Incoming, @Outgoing, Emitter, automatic JSON serialization, and Dev Services starting the broker without you installing anything.

Minimalist diagram showing four interconnected pillars labeled Style, Characteristics, Components, and Decisions, on a dark background

Software Architecture Fundamentals: the 3 laws and 8 expectations every developer should know

Everything in software architecture is a trade-off. A deep dive into Chapter 1 of Fundamentals of Software Architecture: the 3 laws that govern every architectural decision and the 8 expectations of an architect.

Minimalist diagram showing a central 'Agent' node connected to four modules: Soul, Memory, Skills and Tools, on a dark purple background

Qlawkus: Build Personal AI Agents in Java with Quarkus

Introducing Qlawkus, a set of Quarkus extensions for building personal AI agents in Java: memory that’s automatically injected, procedural skills, voice-enabled messaging, and composition via agent.yml.

Pixel art SNES 16-bit of a retro dispatch center with a robot operator routing glowing message packages through neon rails to three distinct receiver nodes, neon SIGNALS sign above

Internal Messaging in Quarkus: Signals, @Receives, and the New Publisher-Subscriber Pattern

Decouple components with Quarkus Signals. Type-safe resolution, @Receives, pub/sub vs unicast vs request-reply, and why Spring has no native equivalent.

SNES 16-bit pixel art of a retro dispatch center with a robot operator routing glowing message packets down neon rails toward three distinct receiver nodes, neon EVENT BUS sign overhead

Internal Messaging in Quarkus: Event Bus, ConsumeEvent, and the Publisher-Subscriber Pattern

Decouple components with the Vert.x Event Bus. Pub/Sub vs Point-to-Point, asynchronous consumers with @ConsumeEvent, and why Spring has no native equivalent.

NES-style pixel art: a retro game console with several cartridges floating above its slot, each cartridge labeled like a plugin (NROM, MMC1, MMC3), a glowing 'ServiceLoader' label on the console reading them automatically

Java SPI: The Built-in Superpower Every Developer Should Know

There is a plugin system hiding inside the JDK that most developers never use on purpose. Java SPI (ServiceLoader) lets you add behavior without touching the code that consumes it. I show it with real code from my NES emulator, kill the fragile META-INF file with Google AutoService, cover the modern JPMS variant, and finish with how Quarkus does the same idea at build time.

SNES 16-bit pixel art sky with a fluffy popcorn cloud (floccus) raining AWS service icons (S3, DynamoDB, Lambda) onto a pixel laptop, neon FLOCI sign above

Floci: a Free, Drop-in LocalStack Alternative Built on Quarkus

LocalStack Community froze in March 2026 and now asks for an auth token. Floci is the no-strings-attached replacement: a free, MIT-licensed, Quarkus-native local AWS emulator. I test it for real: AWS CLI, a real Lambda, two ways of wiring a Quarkus app (Dev Services and Testcontainers), and a LocalStack migration.

SNES 16-bit pixel art beat 'em up scene of a warrior absorbing database crystal power into their body while reactive energy waves radiate outward, neon ACTIVE RECORD sign in the background

The Active Record Pattern and Hibernate Reactive: Entities That Save Themselves in Quarkus

Entities that save themselves! Refactor your orders application to the Active Record pattern with PanacheEntity, learn when to choose Repository vs. Active Record, and enter the reactive world with Hibernate Reactive and @WithTransaction.

SNES 16-bit pixel art of a robot wizard in a red cape holding floating weather and geocoding tools, with code runes in the background

AI Agent Tools in Quarkus LangChain4j: When the REST Client Becomes the LLM's Right Hand

Build an AI agent that calls real REST APIs as tools, without writing any orchestration logic. REST Client + @Tool = automatic tool. The LLM decides when to call, which to call, and with what arguments. Everything runs locally with Ollama via Dev Services, zero API key.