Build a Multi‑Platform Instant Messaging System with Netty & Mina

Project Overview

The article presents an open‑source instant messaging system designed for e‑commerce platforms that require real‑time communication such as notifications and customer service chats. The solution, named CIM, is built on either the Mina or Netty framework and supports WebSocket, Android, iOS, desktop, and other client types, making it suitable for mobile apps, IoT devices, smart homes, embedded development, and backend services.

Architecture

Instant messaging typically follows a simple server‑plus‑client model that enables user‑A to chat with user‑B. The key value of the system lies in its ability to scale via cluster expansion.

Main Modules

The project is split into server and client components. The server integrates Netty with WebSocket, while the client side offers multiple implementations that all communicate with the server; detailed client implementations are not covered in this article.

Directory Explanation

cim-use-examples – examples of how each client uses the system.

cim-client-sdk – source code of the client SDKs.

cim-server-sdk – source code of the server SDKs, providing both Mina and Netty versions (choose one).

cim-boot-server – a Spring Boot server project, developed with IntelliJ IDEA.

Feature Preview

1. Console page:

http://127.0.0.1:8080

2. Android client

3. Web client

Source Code Access

All SDKs are Maven projects that can be packaged into JAR files and imported into the corresponding client or server applications. To obtain the source code, users are instructed to reply with a specific keyword in the associated WeChat public account.