Architecture

Question 1

Event driven architecture

Answer 1

Systems with decouple services that all react to events

Question 2

Microservices

Question 3

MVC

Answer 3

Simple 3 layer architecture

Model - Model is core business logic, data structure etc

View - View is a presentation layer, responsible for controlling output to a “user”

Controller - Adapts user input into the model

Question 4

DDD

Answer 4

Entire design of a system should be based around the business domain, with clear decoupling between the domains (separated by bounded contexts).

Concepts include Entities (the business objects), value objects (immutable data), aggregate root (single source with which to retrieve data)

Question 5

REST

Answer 5

Stateless, idempodent, resource based, built for the web

HATEOAS (Hypermedia as the Engine of Application State) - Essentially dynamic linking between resources and allows a consumer to explore the api easily. Also allows for independent evolution of versions independently between client and server by communicating more of the schema through URIs. Clients can take a URI directly from the JSON response as opposed to building their own.

As an aside, I certainly see the benefit but it definitely adds complication and it may not always be necessary.

Question 6

Clean Architecture

Answer 6

Layers build around the core (entities), entities are acted upon by Use Cases (both comprise the business logic). Controllers/Gateways/Presenters). Then the surrounding architecture around that liek databases, UI, web layer

Question 7

SQL Vs NoSQL, differences and when to use

Answer 7

SQL -
For relational data, data stored as rows and columns with a strict schema. Databases enforce strict data consistency so are well suited when data integrity is critical.

NoSQL - Data is non-relational, or rather amorphous with no strictly defined schemas (making the dbs more flexible). We are simply storing objects of a number of different types. MongoDB is the most popular. NoSQL databases enforce eventual consistency and are therefore better when data integrity is not critical.

Question 8

What is SSR and what is it used for

Answer 8

Server can create a fully “interactive”, high feature html page with javascript, ui libraries etc, and ship the whole page to the client. It is beneficial for SEO

Question 9

Virtual DOM

Answer 9

Used by modern frameworks React and Vue. Responds to the problem that most UI frameworks were updating the DOM too often which caused performance problems.

Instead of rebuilding and rerendering entire parts of the DOM, we update a virtual DOM which in turns is reconciled with the actual DOM, and only minimal changes are made.