🌊 Fluid

🚀 A tiny but agile microservice framework built in Java 24 with first-class support for Docker 🐳, Kubernetes ☸️, and Kafka 📨 event streaming.
Built for speed, scale, and simplicity.

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✨ Features

✅ Java 24-powered lightweight core
✅ 🔁 Kafka-based event-driven architecture
✅ 🐳 Docker-ready containers
✅ ☸️ Kubernetes-deployable out of the box
✅ 🔍 Minimal boilerplate, maximum flexibility
✅ 🔧 DIY microservice stack for builders and hackers
✅ 😍 100% open source

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📦 Getting Started

Build Your Microservice 🛠️

Create a Fluid.java class:

public class Fluid {
    public static void main(String[] args) throws InterruptedException {
        try {
            for (int i = 0; i < 1000; i++) {
                String key = "key-" + i;
                String message = "Message " + i;
                KafkaMessenger.sendMessage("test-topic1", message);
            }
        } finally {
            System.out.println("Shutting down Kafka producer...");
            KafkaMessenger.shutdown();
        }
        Thread.sleep(50000); // Keep the app alive for a bit
    }
}

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Create a Listener Service 🎧

public class MessageService {
    @KafkaListener(topic = "test-topic1", groupId = "test-group")
    public void handleMessage1(String message) {
        System.out.println("1-🕒 Received at " + System.currentTimeMillis());
        System.out.println("1-📥 Message: " + message);
    }
    @KafkaListener(topic = "test-topic2", groupId = "test-group")
    public void handleMessage2(String message) {
        System.out.println("2-🕒 Received at " + System.currentTimeMillis());
        System.out.println("2-📥 Message: " + message);
    }
}

Compound Operations

public class MessageService {
    @KafkaListener(topic = "test-topic1", groupId = "test-group")
    public void handleMessage1(String message) {
        System.out.println("1-🕒 Received at " + System.currentTimeMillis());
        System.out.println("1-📥 Message: " + message);
    }

    @KafkaListener(topic = "test-topic2", groupId = "test-group")
    @SendTo(topic = "processed-topic2")
    public String handleMessage2(String message) {
        System.out.println("2-🕒 Received at " + System.currentTimeMillis());
        System.out.println("2-📥 Message: " + message);
        // Forward processed message to another topic
        return "Processed: " + message;
    }

    @KafkaListener(topic = "test-topic3", groupId = "test-group")
    @ShortCircuit(topic = "error-topic3")
    public void handleMessageWithError(String message) {
        if (message.contains("fail")) {
            throw new RuntimeException("Error detected in message!");
        }
        System.out.println("3-🕒 Message: " + message);
    }
}

🛠️ Architecture

[Fluid App] ---> [KafkaMessenger] ---> [Kafka Broker] ---> [KafkaProcessor] ---> [Your Listener]

• 🔄 Sends and receives messages through Kafka
• 🧩 Plug-n-play message handlers via @KafkaListener
• 🧵 Simple threading and lifecycle controls

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🔮 Roadmap

• 🧵 Async/parallel message handling
• 📊 Metrics (Prometheus or Micrometer)
• 🛑 Graceful shutdown hooks
• 💾 Configuration via fluid.yaml
• 🧠 Built-in retry and backoff strategy

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🤝 Contributing

PRs are welcome! Open an issue or suggest an improvement — let’s make microservices fun and fast again 🧪

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📜 License

MIT License © 2025 Maifee Ul Asad