Understanding WebSockets in Next.js: A Practical Introduction

Real-time applications have become essential in modern web development. Whether you're building a chat app, a collaborative editor, or a notification system, WebSockets offer a powerful way to establish persistent, bidirectional communication between client and server.

In this article, we’ll explore how WebSockets work and how to use them effectively in a Next.js project.

WebSockets are a communication protocol enabling a full-duplex, persistent connection between a client and a server.

Unlike traditional HTTP requests—which are stateless and require a new request for each update—WebSockets keep the connection open, allowing either side to send data at any time.


Test de Quote: ytughj ufgyih yughijk ufygijyfchgvjbk

const test = new Class();
console.log("test");

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Using WebSockets in Next.js

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Self-hosting your own mail server means taking back control over your communications, reducing your dependency on third-party providers, and natively integrating email sending into your own services (monitoring, notifications, applications). In this guide, we'll set up a complete and robust stack on an Ubuntu VPS with:

 — all-in-one mail stack (Postfix, Dovecot, Rspamd, SOGo webmail)

 — so other services on the VPS can send emails

- A domain name (we'll use `yourdomain.com` throughout this guide)

- Docker + Docker Compose plugin installed

- Port 25 unblocked by your hosting provider (open a support ticket if needed)

First, configure these DNS records at your registrar:

| MX | `@` | `mail.yourdomain.com` (priority 10) |

| TXT | `_dmarc` | `v=DMARC1; p=quarantine; rua=mailto:admin@yourdomain.com` |

| CNAME | `autoconfig` | `mail.yourdomain.com` |

| CNAME | `autodiscover` | `mail.yourdomain.com` |

DKIM will be generated later by Mailcow — you'll add it after installation.

apt update && apt upgrade -y

# Open required ports
ufw allow 22/tcp
ufw allow 80/tcp
ufw allow 443/tcp
ufw allow 25/tcp
ufw allow 465/tcp
ufw allow 587/tcp
ufw allow 993/tcp
ufw allow 4190/tcp
ufw enable

# Disable the system Postfix if installed (conflicts with Mailcow)

systemctl stop postfix
systemctl disable postfix

mkdir -p /opt/mailserver/{mailcow,monitoring}
cd /opt/mailserver

Before enabling the HTTPS vhost, generate the certificate using webroot mode. 

# /etc/nginx/sites-available/mailcow-temp
server {
    listen 80;
    server_name mail.yourdomain.com;
    root /var/www/html;
}

ln -s /etc/nginx/sites-available/mailcow-temp /etc/nginx/sites-enabled/
nginx -t && systemctl reload nginx
 
certbot certonly --webroot -w /var/www/html -d mail.yourdomain.com
 
# Verify
ls /etc/letsencrypt/live/mail.yourdomain.com/

5. Nginx Vhost — Reverse Proxy to Mailcow

# /etc/nginx/sites-available/mailcow
server {
    listen 80;
    listen [::]:80;
    server_name mail.yourdomain.com;
 
    # Required for Certbot renewal
    location /.well-known/acme-challenge/ {
        root /var/www/html;
        try_files $uri =404;
    }
 
    location / {
        return 301 https://$host$request_uri;
    }
}
 
server {
    listen 443 ssl http2;
    listen [::]:443 ssl http2;
    server_name mail.yourdomain.com;
 
    ssl_certificate     /etc/letsencrypt/live/mail.yourdomain.com/fullchain.pem;
    ssl_certificate_key /etc/letsencrypt/live/mail.yourdomain.com/privkey.pem;
    ssl_protocols       TLSv1.2 TLSv1.3;
    ssl_ciphers         HIGH:!aNULL:!MD5;
    ssl_prefer_server_ciphers on;
    ssl_session_cache   shared:SSL:10m;
 
    add_header Strict-Transport-Security "max-age=31536000; includeSubDomains" always;
    add_header X-Frame-Options SAMEORIGIN;
    add_header X-Content-Type-Options nosniff;
 
    client_max_body_size 50m;
 
    location / {
        proxy_pass http://127.0.0.1:8181;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto https;  # hardcoded https, not $scheme
        proxy_set_header X-Forwarded-Host $host;
        proxy_http_version 1.1;
        proxy_set_header Upgrade $http_upgrade;
        proxy_set_header Connection "upgrade";
        proxy_connect_timeout 90;
        proxy_send_timeout    90;
        proxy_read_timeout    90;
        proxy_buffers         32 4k;
    }
 
    location /Microsoft-Server-ActiveSync {
        proxy_pass http://127.0.0.1:8181/Microsoft-Server-ActiveSync;
        proxy_set_header Host $host;
        proxy_set_header X-Real-IP $remote_addr;
        proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
        proxy_set_header X-Forwarded-Proto https;
        proxy_connect_timeout 75;
        proxy_send_timeout    3650;
        proxy_read_timeout    3650;
        client_max_body_size  200m;
    }
}

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Using WebSockets in Next.js

Self-Hosted SMTP Server on Ubuntu VPS with Mailcow, Nginx and Docker