Getting started with Redis and Planet 9

Feb 24, 2023

Overview

Starting from the Neptune DXP 22 – Open Edition LTS we can use a Redis server in our applications. Today I want to share with you how I was able to setup a Redis server in order to create a simple application in the App Designer and trigger an event.

Install and start a new Redis server on Windows

Redis is not officially supported on Windows but we can use the Windows Subsystem for Linux (WSL2), just make sure to use Windows 11 or 10 (build 19041 and higher):

open the Windows Command Prompt in administrator mode, run the following command and restart your machine

wsl --install

if the command is not working you may need to enable the optional features in Windows > Run > optionalfeatures.exe and turn on Virtual Machine Platform, Windows Hypervisor Platform and Windows Subsystem for Linux, then restart your machine
open again the Windows Command Prompt and run

wsl

the first time you will need to create a new UNIX username and password
install Redis with the following commands (enter the password you created before)

curl -fsSL https://packages.redis.io/gpg | sudo gpg --dearmor -o /usr/share/keyrings/redis-archive-keyring.gpg

echo "deb [signed-by=/usr/share/keyrings/redis-archive-keyring.gpg] https://packages.redis.io/deb $(lsb_release -cs) main" | sudo tee /etc/apt/sources.list.d/redis.list

sudo apt-get update

sudo apt-get install redis

run the Redis server

sudo service redis-server start

you can test the server connection (you will receive PONG response if is running)

redis-cli
ping

Install and start Redis server on other OS

You can find the documentation in the official website:

Redis Installation

Set the Redis URI inside Planet 9 settings

Open the Planet 9 Cockpit and go inside the System Settings > Database
In the In-memory database input enter the following URI (replace 127.0.0.1 if is not local)

redis://127.0.0.1:6379

Restart the Planet 9 instance

Create a new event

In the P9 Cockpit go to the Events and create a new one (Event Action needs to be App, as we will use it later in the APP Designer)

Create the App

Open the App Designer and create a new application
In HTML5 Document insert the following elements: sap.m.Shell > sap.m.App > sap.m.Page > sap.m.TextArea
In Resources create two folders Redis, Javascript

Drag and drop a new EventListener and EventTrigger elements inside the Redis folder

Select the EventTrigger, rename as SendText and under the property event select the one created before. This element will be used when the user will change the content of the text area, in order to send the new text via Redis to other users connected in the same app

Select the sap.m.TextArea. go inside the liveChange event and use this code to call the Event Trigger

let newText = this.getValue();
triggerSendText({text: newText});

Select the EventListener element, rename it as ReceiveText and set the property event with the one created before
Open the action event of the Listener element and add the following code, this will update the text area content for all users connected to the app

if (data.text) {
    textArea.setValue(data.text);
};

Test the application

Open the app in two different windows and start typing inside the text area. Here a GIF:

Open GIF