ULT (UDP Like TCP) — Proof of Concept

This is a Proof of Concept.
It is not production-ready and is meant solely to demonstrate core ideas of building a reliable messaging system on top of UDP.

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What is ULT?

ULT (UDP Like TCP) is an experimental protocol that brings TCP-like reliability to UDP-based communication.

The goal is to simulate:

• Ordered delivery
• Complete message reconstruction
• Lightweight, connectionless transmission

All built using raw UDP sockets in Node.js.

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What This PoC Demonstrates

• Breaking a JSON payload into chunks
• Sending each chunk over UDP with metadata:
  • chunk content
  • index
  • total chunk count
• Reassembling the original message on the server
• Measuring per-chunk arrival delay

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How to Run

Prerequisites

• Node.js (v14+ recommended)

1. Start the Server

node server.js

This will bind a UDP server on port 41234 and log incoming chunks with timing details.

2. Start the Client

node client.js

The client creates a JSON payload, splits it into characters, and sends them one-by-one to the server.

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Packet Structure

Each UDP message contains an array in string form:

[chunk, index, totalLength]

Next Steps (Ideas for Future)

• Resend logic for missing chunks

• ACK system (server ↔ client communication)

• Chunk grouping (send multiple characters per packet)

• Message IDs (support multiple messages simultaneously)

• Binary protocol support (more efficient than JSON)

Why Do This?

UDP is fast but unreliable. TCP is reliable but heavy.

ULT explores the space in between AND that gives us:

• The speed of UDP

• The control to define your own reliability model