Matheus Oliveira

A 16-bit SNES pixel art illustration of a community hub where characters catch bugs in jars, write on scrolls, discuss around a fountain, and donate gold coins.

How to Contribute to Open Source Without Writing Code

Think contributing to Open Source is just about opening PRs? Discover how to help the community through issues, discussions, articles, and donations, even without focusing on code.

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.

OCI Notifications and Event-Driven Architecture

Event-Driven on the Free Tier: OCI Notifications (ONS) as an Event Bus

Discover how to implement Event-Driven Architecture on OCI Always Free using OCI Notifications (ONS). ONS delivers 1M HTTPS notifications/month and 1000 emails/month for free.

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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.

SNES 16-bit pixel art beat 'em up scene of a street fighter shattering an in-memory list enemy while crystal database tables rise from the ground, neon PANACHE sign in the background

Persistence with Panache: From Spring Data JPA to the Repository Pattern in Quarkus

No more in-memory lists! Evolve your orders application with real persistence using Hibernate ORM with Panache in the Repository pattern. Dev Services, pagination, HQL queries and the transition from Spring Data JPA.

Quarkus Native on Knative cold start benchmark

Quarkus Native on Knative: 5x Faster Cold Start, 20x Less Memory

What does a 3-second cold start cost you in production? SLO breaches on every scale-from-zero event and 19x more cloud spend on memory. I benchmarked a real Quarkus app in containers and the numbers make the case.