Install PostgreSQL on Ubuntu 20.04

Install postgreSQL packages

sudo apt update
sudo apt install postgresql postgresql-contrib

Docker Private Registry

Queue	Topic
The point-to-point or queue model works by the sender to receiver setup	Publish/subscriber or topic model works by bulletin setup
Acknowledgement of the identity of the receiver and oftentimes the sender	Anonymity in the identities of both the subscriber and publisher
Only allowed one recipient	Multiple recipients
The sender and receiver do not have to be both active at the same time	Timing is very vital
The sender will receive a notification when the message gets to the receiver	Not notify you with such, and there is even a risk that you will have no subscribers

Download the Termux from this page Termux. Please scroll down to download the APK file instead of the F-Droid button.

Since Spring 2.0.0, Spring provides WebApplicationType Enum to give more controls of SpringApplication. Currently it supports the following types:

None: The application should not run as a web application and should not start an embedded web servicer.
REACTIVE: The application should run as a reactive web application and should start an embedded reactive web server.
SERVLET: THe application should run as a servlet-based web application and should start an embedded servlet web server.