Megaphone distributes events to many web browsers

Description

This project is essentially a Redis-to-WebSocket adapter in the sense that it will publish to WebSocket clients, whatever string you publish to Redis.

If you connect to redis via redis-cli and type publish trades "some json here", this project will send over WebSocket to all connected clients the message "some json here".

This means we could reuse this project for trades, ticker and orderbook without any code change, only a few runtime environment variables changed such as what topic we subscribe to in Redis.

Building

• git clone --recursive git@github.com:bitwyre/megaphone.git
• make deps -C megaphone (requires autotools, autoconf, automake for building libuv)
• make -C megaphone

Now you should have an executable, megaphone, without any non-standard dependencies to worry about (you can move this executable across different Linux systems without breakage).

Usage

Megaphone is a stand-alone executable you launch with a few environment variables:

• REDIS_HOST is the address/hostname to the main, internal, Redis pub/sub node
• REDIS_PORT is the port to said Redis node
• REDIS_TOPIC is the topic we subscribe to, and listen to events on. What you publish to Redis on this topic will be sent to all WebSocket clients connected to this Megaphone instance
• SERVICE_IP is the hostname of the WebSocket server
• SERVICE_PORT is the port of the WebSocket server
• SERVICE_PATH is the path of the WebSocket server

Example:

• You need a redis-server running, for instance on localhost and port 6379.

• REDIS_HOST=localhost REDIS_PORT=6379 REDIS_TOPIC=trades ./megaphone launches one instance, you may launch as many you want, distributing the load among megaphone instances.

• Now you may test by starting redis-cli and typing publish trades "hello world!", which should trigger a distribution of "hello world! over all to megaphone connected WebSocket clients.

Docker Example

docker run --rm \
    -e "REDIS_TOPIC=pubsub_topic" \
    -e "REDIS_PORT=6379" \
    -e "REDIS_HOST=127.0.0.1" \
    -e "SERVICE_IP=127.0.0.1" \
    -e "SERVICE_PORT=4545" \
    -e "SERVICE_PATH=/ws/topic" \
    --net=host \
    bitwyre/megaphone:latest

Author

• Alex Hultman

Contributors

• Dendi Suhubdy
• Aditya Kresna
• Yefta Sutanto

Copyright

• © 2020 Alex Hultman
• © 2020 Bitwyre Technologies LLC