Distributed Stock Ticker Notification System (Pub/Sub in Java)

Real-time stock/news ticker notifications built with a custom Publish/Subscribe architecture in Java using TCP sockets — no Kafka/RabbitMQ.

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🚀 Quickstart (30 seconds)

1. Start Master Node
2. Start Secondary Node
3. Start Subscribers
4. Watch live topic notifications stream in real-time 🚀

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✨ Key Features

• Topic-based subscriptions (e.g., Economic Reports, Sector Performance, Inflation)
• Master–Secondary coordination for routing + registration
• Multiple subscribers receive real-time updates based on topics
• Lightweight TCP protocol (simple message/command handling)
• Optional Docker + docker-compose setup for quick runs

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🧠 Architecture Overview

Diagram (high-level)

Publisher/News Generator
        |
        v
  Secondary Node (5041)  <---->  Master Node (5040)
        |
   -----------------
   |       |       |
Sub1     Sub2     Sub3
(topic filters + real-time updates)
(pic filters + real-time updates)

Master Node (port 5040)

• Accepts registration from nodes/subscribers
• Maintains subscriber ↔ topic mappings
• Routes updates to the correct recipients

Secondary Node (port 5041)

• Connects to Master for coordination
• Accepts subscriber connections
• Forwards/relays topic updates to subscribers

Subscribers

• Register and subscribe to topics
• Receive real-time notifications when updates are published

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📁 Project Structure

• master_node/ → Master server (server1.java)
• secondary_node/ → Secondary server (server2.java)
• subscriber_1/, subscriber_2/, subscriber_3/ → Subscriber clients
• Front end/ → Optional simple UI assets
• docker-compose.yml → Multi-container orchestration
• Dockerfile → Base container setup

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🏃 How to Run (Local)

Open 4 terminals and run in this order.

1) Start Master Node

cd master_node
javac server1.java
java server1

2) Start Secondary Node

cd ../secondary_node
javac server2.java
java server2 secondary_node

3) Start Subscribers (separate terminals)

cd ../subscriber_1
javac subscriber1.java
java subscriber1 subscriber_1

Repeat similarly for subscriber_2 and subscriber_3.

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🐳 How to Run (Docker)

docker-compose up --build

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✅ Example Flow

1. Subscriber connects and registers (e.g., subscriber_1)
2. Subscriber subscribes to one or more topics
3. Nodes publish stock/news updates
4. Subscriber receives real-time messages for subscribed topics

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🛠 Tech Stack

• Java (17+)
• TCP Socket Programming
• Distributed Systems (Pub/Sub from scratch)
• Docker / Docker Compose (optional)

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🧹 Repo Cleanup (important)

Make sure no .class files are tracked in GitHub:

git ls-files | grep "\.class$"

If it prints anything, remove them from tracking and push cleanly.

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📌 Future Improvements

• Heartbeats + retry logic for fault tolerance
• Message serialization (JSON / Protobuf)
• Topic persistence + replay
• Monitoring metrics (latency, throughput)