Walkthrough: https://dev.to/nowke/building-real-time-dashboard-using-react-graphql-subscriptions-and-redis-pubsub-2gip

Prerequisites

• Install NodeJS (LTS)
• Install Redis (Server and Client)
  • MacOS - brew install redis
• Install Yarn
  • MacOS - brew install yarn

Clone the repository

git clone https://github.com/nowke/realtime-dashboard-demo.git

Start Redis server

redis-server

Install dependencies

cd server
yarn install

Start the server

yarn start

Server will be running at http://localhost:4000/. The below UI will be rendered

Install dependencies

cd worker
yarn install

Start the worker

yarn start

The following logs will be printed,

Starting worker
Scheduled Jobs for CPU, Traffic, distribution, messages
Fetched new results for MESSAGES
Fetched new results for CPU
Fetched new results for DISTRIBUTION
Fetched new results for CPU
Fetched new results for MESSAGES
Fetched new results for TRAFFIC
...

Install dependencies

cd client
yarn install

Start client

yarn start

Client will be running at http://localhost:3000. Dashboard picks up initial data from Redis, update itself at intervals.

Alternatively, subscribe to Redis channel directly using SUBSCRIBE <channel> command to get the feel of it!

For example, subscribe to CPU utilization channel - cpu. Observe values getting published to the channel while the worker is running.

$ redis-cli
127.0.0.1:6379> SUBSCRIBE cpu
Reading messages... (press Ctrl-C to quit)
1) "subscribe"
2) "cpu"
3) (integer) 1
4) "message"
5) "cpu"
6) "{\"cpu\":{\"percentage\":51}}"
7) "message"
8) "cpu"
9) "{\"cpu\":{\"percentage\":74}}"
10) "message"
11) "cpu"
12) "{\"cpu\":{\"percentage\":51}}"
13) "message"
14) "cpu"
15) "{\"cpu\":{\"percentage\":43}}"
...

Kill the worker process to stop the dashboard from getting new values. Now, publish the values directly from Redis using PUBLISH <channel> <value> command.

Note: Provide a valid JSON String as value for the dashboard to render the value correctly.

Publish a 53% value as CPU percentage

$ redis-cli
127.0.0.1:6379> PUBLISH cpu "{\"cpu\":{\"percentage\":53}}"
(integer) 1
127.0.0.1:6379>

And, the dashboard's CPU panel shows 53% value immediately

Available channels in the example are,

• cpu
• traffic
• distribution
• messages

• GraphQL Subscriptions
• Redis PubSub