PubMQ

PubMQ is a lightweight message queue and pub/sub library that uses a custom protocol implemented as a small layer on top of the UDP protocol. It is idea for real-time communication where asynchronous messages are broadcasted within channels.

Note that PubMQ is connectionless and unreliable (UDP) by design and thus ideal for time critical applications.

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Installation

Client:

npm install --save pubmq

Server:

Install PubMQ package globally:

npm install -g pubmq

Install PubMQ server on port 14850:

pubmq install -p=14850

Create startup script to launch PubMQ on restart: (Checkout PM2 startup script for more info)

pubmq startup <distribution>

Usage

Subscriber

const PubMQClient = require("pubmq").Client;
let client = new PubMQClient();

// Connect to a PubMQ Server
client.connect("localhost:14850", (error) => {
  if (error) throw error;
  
  // Subscribe to the test channel (channels are automatically created)
  client.subscribe("test");
  
  // Listen for messages (note the semi-colon prefix)
  client.on(":test", (message) => {
    // Message is a buffer, convert to string
    let strMessage = message.toString("utf8");
    console.log(strMessage);
  });
});

// Output after pub: Hello World

Publisher

const PubMQClient = require("pubmq").Client;
let client = new PubMQClient();

// Connect to a PubMQ Server
client.connect("localhost:14850", (error) => {
  if (error) throw error;
  
  // Publish a message to test channel
  client.publish("test", "Hello World");
});

Features & Limitations

Features

• Lightweight code and protocol
• Pub/Sub
• Unsub
• Message Queue
• TTL for Messages
• Direct messaging (upcoming)

Limitations

• Message size is limited to max UDP packet size (about 64kb)
• Messages are only stored in memory (since messages are short lived this shouldn't be an issue)
• Deliveries aren't guaranteed
• No congestion avoidance/control (planned fix)

License

MIT