AWS Cloud Developer: Fullstack-Building and Deploying

Question 1

How should code be split?

Answer 1

by feature

Question 2

What is the benefit of splitting code based on features

Answer 2

Reduces technical debt

The goal as the system continues to grow, is to minimize refactoring outside of specific features. As you continue to learn cloud and explore microservices, often entire features might be ported to their own servers infrastructure making this loose coupling even more critical.

Question 3

How should backend file-structure be structured?

Answer 3

src/
    server.js
    controllers/
        v0/
            index.router.js
            feed/
                models/
                    Feed.js
                routes/
                    feed.router.js
            user/
                models/
                    User.js
                routes/
                    user.router.js

Question 4

ORM

Answer 4

Intro to Object-Relational Maps (ORM)

The Object part is the one you use with your programming language ( python in this case )

The Relational part is a Relational Database Manager System ( A database that is ) there are other types of databases but the most popular is relational ( you know tables, columns, pk fk etc eg Oracle MySQL, MS-SQL )

And finally the Mapping part is where you do a bridge between your objects and your tables.

(ORM) is a technique that lets you query and manipulate data from a database using an object-oriented paradigm. When talking about ORM, most people are referring to a library that implements the Object-Relational Mapping technique, hence the phrase “an ORM”.

An ORM library is a completely ordinary library written in your language of choice that encapsulates the code needed to manipulate the data, so you don’t use SQL anymore; you interact directly with an object in the same language you’re using.

Question 5

Models

Answer 5

A model is the data representation of some group of data. In object-oriented programing terms, a model is an object and is represented by a new class. It should usually represent a noun such as a user, a feed item, an order, etc. We use the @Table decorator and extend the base sequelize Model class to link our model to our database table.

Question 6

Migrations

Answer 6

Migration refers to modifying the database (by adding or removing tables or columns, for instance, or switching to a different dialect of SQL) to a newer version (usually based on new business requirements).
Up migration is the process of modifying the database to a newer state.
Down migration is the process of reversing an up migration, to a prior state.

Question 7

Seeding

Answer 7

Seeds are default rows of data that will be inserted upon database formation. This may be helpful when provisioning databases frequently for specific applications and having welcome data populated, or when running tests on staging systems to simulate real-world conditions.

Question 8

Associations

Answer 8

Associations allow our models to reference other models. For example, consider people and dog relationships. We might represent this as a person table and dog table.

Question 9

One-To-One Association

Answer 9

If the person has only one dog, we can use a foreign key column in the person table to reference a single row in the dog table. This is known as a One-To-One association.

Question 10

One-To-Many Association

Answer 10

However, a person may have many dogs. In SQL we might represent this using a new separate table known as a Join table. This is essentially a table of two foreign key columns, one for person table and one for dog table. We can then find all dog foreign keys for a given person foreign key to find the relationship.

Question 11

Reverse proxy

Answer 11

In computer networks, a reverse proxy is a type of proxy server that retrieves resources on behalf of a client from one or more servers. These resources are then returned to the client, appearing as if they originated from the reverse proxy server itself.

Question 12

Proxy

Answer 12

a proxy server is a server application or appliance that acts as an intermediary for requests from clients seeking resources from servers

Question 13

NGINX proxy

Answer 13

NGINX reverse proxy is setup to help rout traffic, balance load, and handle concurrent requests

Question 14

Basic Elastic Beanstalk architecture

Answer 14

Load Balancer
EC2 instance
     - NGINX reverse proxy
     -Application
DB
FS

Question 15

Config.yml file

Answer 15

This is the set of instructions Elastic Beanstalk will follow when provisioning your AWS infrastructure and deploying your code.