web applications architecture

Question 1

what is web applications architecture

Answer 1

a framework that defines interactions between different components of a web application

Question 2

what are the 3 components of a web application

Answer 2

front end; client side
back end; server side
database

Question 3

front end

Answer 3

handles user interface and experience

Question 4

back end

Answer 4

processes business logic, handles data storage and interacts with the db

Question 5

database

Answer 5

stores and manages application data

Question 6

what is the primary function of web servers

Answer 6

deliver web pages to networked clients

Question 7

what do webservers do

Answer 7

they are software that take a request in http format for a resource over a network then serves it back to the client as a payload to a http response

Question 8

request response cycle

Answer 8

client request, the server processing and the response delivery

Question 9

how does the client server model work

Answer 9

client requests data and services from the server
server processes requests and returns the appropriate response

Question 10

what is the role of http in the client server model

Answer 10

protocols the facilitate the interaction

Question 11

what are the four main types of web application architecture

Answer 11

monolothic
micro services
single and multi page applications

Question 12

monolithic architecture

Answer 12

a single indivisible unit with all components interconnected
the backend front end and db are tightly coupled

Question 13

how does the server and client interact in a monolithic architecture

Answer 13

the server sends complete html pages to the client for every user request

Question 14

+ monolithic architecture

Answer 14

simpler to develop and deploy
easier debugging

Question 15

– monolithic architecture

Answer 15

scalability issues; harder to update and maintain

Question 16

microservices architecture

Answer 16

small independent services that communicate via apis

Question 17

+ microservices architecture

Answer 17

scalability and flexibility in using different technologies

Question 18

– microservices architecture

Answer 18

complexity in management and deployment

Question 19

single page applications

Answer 19

the entire front end is uploaded initially and subsequent interactions happen without full page reloads

Question 20

how is content updated in single page applications

Answer 20

by making api calls to the backend

Question 21

+ single page applications

Answer 21

faster user experience and reduces server load

Question 22

– single page api

Answer 22

search engine optimisation (seo) challenges; initial load time can be high

Question 23

multi page applications

Answer 23

multiple pages each loaded separately from the server

Question 24

how do multi page applications work

Answer 24

when users navigate to different pages the browser sends a request to the server which returns a new html page for each request

Question 25

-- multi page applications

Answer 25

more server load slower navigation compared to single page

Question 26

+ multi page applications

Answer 26

better for seo; easier to maintain certain types of applications

Question 27

what is a web page made up of

Answer 27

has a base html file including several referenced objects

Question 28

examples of objects in html

Answer 28

html file jpeg image audio/video file

Question 29

front end technologies

Answer 29

html css javascript

Question 30

html

Answer 30

structures the content on the webpage

Question 31

css

Answer 31

styles and visually formats the content

Question 32

javascript

Answer 32

adds interactivity and dynamic features

Question 33

modern front end frameworks

Answer 33

streamline development and manage complex ui states

Question 34

backend technologies

Answer 34

server side languages; e.g. java python webservers APIs;RESTful

Question 35

webservers

Answer 35

serve webpages to users

Question 36

APIs

Answer 36

services that allow communication between the front and backend

Question 37

deployment

Answer 37

making an app available for use on a server

Question 38

what are the 3 parts of the deployment environment

Answer 38

deployment, production and staging environment

Question 39

deployment environment

Answer 39

local machines where developers write and test code

Question 40

production environment

Answer 40

the live environment where the product is available to users

Question 41

staging environment

Answer 41

a replica of the production environment used for final testing

Question 42

what are the 3 types of deployment models

Answer 42

on premises cloud based hybrid

Question 43

on premises deployment model

Answer 43

hosting the app on physical servers owned and managed by the organisation

Question 44

cloud based deployment model (+ what benefits does it offer)

Answer 44

using cloud services to host the app offering scalability and reducing operational overhead

Question 45

hybrid deployment model

Answer 45

on premises and cloud based

Question 46

what are the 3 cost considerations in deployment

Answer 46

initial cost; setup and deployment (including server and cloud costs) ongoing costs; maintenance, scaling, monitoring optimisation; using autoscaling and pay-as-you-go models to optimise costs

Question 47

what are some performance metrics and explain them

Answer 47

response time; time for the server to process a request and send a response latency; delay between client request and servers initial response throughput; number of requests successfully handled within a given time frame error rate availability security resource utilisation

Question 48

scalability

Answer 48

the ability of an app to handle increasing loads and maintain performance goals

Question 49

horizontal scaling

Answer 49

adding more machines to handle load complicates all scenarios except the simplest

Question 50

vertical scaling

Answer 50

increasing the power of existing machines

Question 51

+ vertical scaling

Answer 51

more machines can get expensive nothing changes drastically

Question 52

what are two forms of performance optimisation

Answer 52

load bearing caching

Question 53

load balancing

Answer 53

distributing the load evenly across two or more servers

Question 54

caching

Answer 54

exploits locality by moving content closer to the user

Question 55

in which places can caching be done

Answer 55

in browser network or server

Question 56

why does caching work

Answer 56

less hops means less latency less congestion

Question 57

what is a positive and negative of load balancing and how does it work with hardware

Answer 57

higher performance and cost rewrites headers at layer four and adjusts the dns there is a tcp connection between the client and server

Question 58

how does load balancing with software work

Answer 58

echos http requests to particular servers tcp connection between the client and balancer