Java Microservices: CQRS & Event Sourcing with Kafka

IaaS is the layer of cloud computing where you rent raw infrastructure through an API, meaning virtual machines, disks and networks, and take responsibility for the operating system and everything you install above it.

PaaS is a hosting layer that takes your source code and turns it into a running application for you, owning the machines, the runtime, the build, the routing, the certificates and the restarts, so that shipping becomes a push rather than a project.

Serverless computing runs your code only while an event is calling it: the provider conjures an execution environment on demand, throws it away afterwards, and charges for work performed instead of for capacity sitting idle.

SSL/TLS is the protocol that encrypts the connection between a browser and a server and, by way of a certificate signed by a certificate authority, proves the server is entitled to answer for the domain in the address bar.

A domain name is an address in the internet's public namespace that you rent through a registrar for a yearly fee, and it remains yours only while the registrar account holding it stays paid up and under your own control.

Caching keeps the result of expensive work, such as a rendered page or a database query, and serves that stored copy until it expires, making it the largest single source of speed on any busy website.

Full-stack development is the ability to build both halves of a web application: the front end that runs in the browser (HTML, CSS and JavaScript) and the back end that runs on a server (a language, a framework and a database), plus the API that joins them.

A framework is a body of code that imposes a structure on the application built with it: it decides how files are organised, when the application's own code is called and how its parts talk, whereas a library is code the application calls when it chooses.

Object-oriented programming is a way of organising a program as objects, each holding its own data and the operations allowed on it, with classes as the templates objects are made from, so that the code models the things it is about rather than the steps the computer takes.