WebSocket Erlang Project

Erlang Websocket project to enable real time communication.

How it works?

• Introduction

• Realtime channel

• Configuration channel

How do I get set up?

• Install NodeJS 10
• Install npm
• Install Gulp npm install -g gulp@3.9.0
• Install Gulp dependencies npm install
• Install Erlang OTP_20.3.8.9 (http://www.erlang.org/download.html) ** I recommend you to use the Erlang Version Manager (https://github.com/robisonsantos/evm). Install these needed dependencies before install Erlang: apt install libncurses5-dev autoconf gcc make ** Optionally you can install the following packages for Erlang: *** OpenSSL apt install libssl-dev
• Install Rebar 3 (http://www.rebar3.org). Use version 3.14.3 at minimum. (There is a copy of this rebar3 version at root project folder)
• Install Erlang/Rebar dependencies gulp erlang:deps
• Compile and execute the project gulp run
• See available tasks gulp

Protocol communication

The protocol uses binary format to transfer data. It is as follows.

version:2 bytes|client_key: 20 bytes|payload: rest bytes

The methods (buffer = Utils.createMultiscreenMessage(receiver, payload)) and ({ version, sender, payload } = Utils.readMultiscreenMessage(buffer)) can be used to create a valid message.

Deploy production version

To deploy a production version of the code in a server, follow the below steps:

• Execute the command ../rebar3 as prod tar inside the rebar folder of the project source code
• Create a folder multiscreen folder in the /opt/ folder of the computer to deploy
• Copy the generated .tar.gz file to the /opt/multiscreen folder and extract it
• Create a file erlang-websocket-server.service in the folder /etc/systemd/system folder with the following content:

[Unit]
Description=Erlang Websocket Server

[Service]
Type=simple
RemainAfterExit=yes
Environment=HOME=/opt/multiscreen
WorkingDirectory=/opt/multiscreen
ExecStart=/opt/multiscreen/bin/multiscreen_ws daemon
ExecStop=/opt/multiscreen/bin/multiscreen_ws stop

[Install]
WantedBy=multi-user.target

• Install and start the new created service with the following commands:

** sudo systemctl start erlang-websocket-server.service ** sudo systemctl enable erlang-websocket-server.service

Deploy as Docker container

To deploy the code as a docker container, follow the below steps:

• Execute the command docker build . -t websocket-server:latest
• Then execute the command docker run -d -p 8080:8080 websocket-server:latest

Usage

• A sample is available at http://<YOUR_IP_ADDRESS>:8080/multiscreen/sample.html).