This is the Node.js Socket.IO server of the UDB3 search project.

Use it in conjunction with the UDB3 AngularJS application and the UDB3 backend implementations (UDB3 Backend.

[TOC]

Getting started

Requirements

Ensure you have installed:

• Node.js and the npm package manager
• Redis

Download code & required libraries

Clone the [UDB3 Socket.IO][udb3-websocket-server] git repository.

Install its dependencies with npm:

npm install

Start the server

Start the Socket.IO server, which listens on port 3000:

node app.js

By default a configuration file config.json is used, when present.

For a list of configuration options, read the next section.

Configuration options

• redis: Options passed to the socket.io-redis adapter. For more info, read the socket.io-redis documentation. Default: empty.

Running it as a service

We recommend to use systemd to launch and control the UDB3 Socket.IO server process.

Below is a sample systemd service unit file, named uitdatabank-websocket-server.service. Replace the WorkingDirectory value with the path to your git clone, and replace the User and Group values with the unprivileged user you want to run the server as. Put the configuration file at the right location (/etc/systemd/system)

[Unit]
Description=UiTdatabank Websocket server
After=syslog.target network.target remote-fs.target nss-lookup.target

[Service]
User=www-data
Group=www-data
PIDFile=/var/run/udb3-websocket-server.pid
EnvironmentFile=-/etc/default/udb3-websocket-server
WorkingDirectory=/var/www/udb3-websocket-server
ExecStart=/usr/bin/node --title uitdatabank-websocket-server app.js
Restart=on-failure
RestartSec=10s
Type=simple

[Install]
WantedBy=multi-user.target

Then make systemd reload its configuration:

sudo systemctl daemon-reload

Verify the uitdatabank-websocket-server process is running correctly:

sudo systemctl status uitdatabank-websocket-server

This should output something like this (possible among other processes):

● uitdatabank-websocket-server.service - UiTdatabank Websocket server
   Loaded: loaded (/lib/systemd/system/uitdatabank-websocket-server.service; enabled; vendor preset: enabled)
   Active: active (running) since do 2024-09-12 13:46:01 UTC; 1 months 12 days ago
 Main PID: 4338 (uitdatabank-web)
    Tasks: 11
   Memory: 55.9M
      CPU: 1min 59.334s
   CGroup: /system.slice/uitdatabank-websocket-server.service
           └─4338 uitdatabank-websocket-server

Warning: Journal has been rotated since unit was started. Log output is incomplete or unavailable.

Running it behind a reverse proxy

Apache HTTP Server

Install and enable the mod_rewrite, mod_proxy and mod_proxy_wstunnel Apache modules.

Configuration sample to make Apache proxy incoming requests to the Socket.IO server running on port 3000 on the same host:

ProxyRequests Off
ProxyPreserveHost Off
ProxyPass / http://127.0.0.1:3000/
ProxyPassReverse / http://127.0.0.1:3000/

RewriteEngine On

RewriteCond %{HTTP:Upgrade} websocket [NC]
RewriteCond %{HTTP:Connection} upgrade [NC]
RewriteRule /socket.io/(.*)$ ws://localhost:3000/socket.io/$1 [P]