Kjhk 90.7 FM API Gateway

This project implements an API gateway and a WebSocket server that listens for metadata from a TCP server and broadcasts it to connected clients. The primary use case is to provide real-time updates to clients using the KJHK App on Android/iOS about new media playing on a Zetta RCS system.

Features

• API Gateway: Connects client to the appropriate service (room for future services such as DJ Scheduling)
• TCP Server: Listens for metadata sent from Zetta RCS.
  • Supported metadata:
    • New Media Playing
• WebSocket Server: Sends metadata to all connected clients.
  • Example Response:

  {
      "track": "I Know It's Over",
      "album": "The Queen Is Dead",
      "artist": "The Smiths",
      "length": 347893.3,
      "timestampUTC": "2024-09-24T00:32:22Z",
      "timestampCST": "2024-09-23T19:32:22Z"
  }

Connection Workflow

1. Client Connection:
   • The client (e.g., an app) connects to the Nginx server on port 80.
   • The client mentions the target endpoint (metadata) in the request.
2. Nginx Reverse Proxy:
   • Nginx forwards the WebSocket connection to the API gateway on port 8081.
3. Subscription Confirmation:
   • The API gateway then routes the connection to the particular service requested by the client (metadata).
   • The WebSocket server (running on port 8080) sends metadata once a successful connection is established.
   • The server also sends out the most recent metadata to the client once they connect.
4. Metadata Reception:
   • The client receives metadata from the WebSocket server.
5. Heartbeat Mechanism:
   • The client sends a heartbeat to the Nginx server to keep the connection alive.
6. Client Disconnection:
   • The client disconnects from the WebSocket server.
7. Server Disconnection:
   • Server has graceful shutdown mechanism to ensure it disconnects all clients and performs necessary cleanups.

Getting Started

Prerequisites

• Docker
• Docker Compose

Installation

1. Clone the repository:

   git clone https://github.com/KJHK-907/gateway.git

2. Running the Services:

   docker compose up --build

3. Client connection example (Node.js)

   const WebSocket = require('ws');
   
   const targetEndpoint = "metadata";
   const ws = new WebSocket(`ws://localhost/api/?target=${targetEndpoint}`);
   
   ws.on('open', function open() {
   console.log('Connected to the server');
   setInterval(() => {
       ws.ping();
   }, 30000);
   });
   
   ws.on('message', function incoming(data) {
   console.log('Received from server:', data);
   });
   
   ws.on('error', function error(err) {
   console.error('WebSocket error:', err);
   });
   
   ws.on('close', function close() {
   console.log('Disconnected from the server');
   });

License

This project is licensed under the MIT License.