Nchan¶

Nchan is a scalable, flexible pub/sub server for the modern web, built as an NGINX module.

Repository: slact/nchan
NGINX Extras: nginx-module-nchan

Installation¶

RHEL/CentOS/AlmaLinux/Rocky (Recommended)From Source

sudo dnf -y install https://extras.getpagespeed.com/release-latest.rpm
sudo dnf -y install nginx-module-nchan

Enable in /etc/nginx/nginx.conf:

load_module modules/ngx_nchan_module.so;

git clone https://github.com/slact/nchan.git
cd nginx-1.x.x
./configure --add-module=../nchan
make && sudo make install

Features¶

Standalone or shim — Run as a dedicated server or between your app and subscribers
Multiple protocols — WebSockets, EventSource (SSE), Long-Polling, HTTP Streaming
Scalable — Handles thousands to millions of concurrent connections
Flexible storage — Memory, on-disk, or Redis for message buffering
Horizontal scaling — Multiple NGINX instances with Redis backend
Channel multiplexing — Each subscriber can listen to up to 4 channels
Authentication — Custom application URL for subscriber verification
Debug channel — Events meta channel for debugging

Publishing & Subscribing¶

Publish: HTTP POST or WebSocket
Subscribe: WebSocket, Long-Polling, EventSource, Interval Polling

History¶

Nchan was originally the Nginx HTTP Push Module. It was renamed after a complete refactoring and overhaul.

Quick Example¶

# Publisher endpoint
location /pub {
    nchan_publisher;
    nchan_channel_id $arg_id;
}

# Subscriber endpoint (WebSocket, EventSource, Long-Poll)
location /sub {
    nchan_subscriber;
    nchan_channel_id $arg_id;
}

See the NGINX Extras documentation for configuration details.