Lec1 - Web Application Architecture

Question 1

Web application architecture

Answer 1

• Framework defining interactions between components of a web app (e.g. UI, Server logic, databases)
• Determines performance, scalability and security of web app
• Front-end (client side), Back-end (server side)

Question 2

Client-server model

Answer 2

Request services as client, server provides response. The request-response cycle repeats.

Question 3

multi-page apps

Answer 3

Multiple pages loaded separately. When new pages accessed, browser sends request to server, which returns a new page for the request.

Question 4

Advantage of multi-page apps (MPA)

Answer 4

• better for SEO (search engine optimisation) (loads it faster because it only has to load one page at a time), easier to maintain certain types of application

Question 5

Negative of MPA?

Answer 5

More server load (each new page means a new request) so slower navigation (slow to wait for page to load)

Question 6

single page applications (SPA)

Answer 6

Front-end loaded initially in entirety and further interactions are handled without full-page reloads (dynamic content updates). Updates happen by making API calls to back-end.

E.g. Google maps - each scroll
Is new content, only content updates not whole page

Question 7

Advantages of SPA

Answer 7

Faster user experience
Reduced server load

Question 8

Disadvantages of SPA

Answer 8

SEO challenges (as whole front end loaded at once) and so initial load times can be high

Question 9

Monolithic architecture

Answer 9

Single indivisible unit
Components are interconnected (database and backend are tightly coupled)
(One big system)

Question 10

Pros and cons of monolithic architecture

Answer 10

+Simpler to develop and deploy, easier debugging
-Scalability issues (harder to update and maintain)

Question 11

Micro services architecture

Answer 11

Small independent services that communicate via APIs

Question 12

Pros and cons of micro services architecture

Answer 12

+Scalability and flexibility (using different technologies to complete tasks and it all working cohesively)
- Complex to manage and deploy

Question 13

DNS

Answer 13

DNS provides a distributed database we can query for the IP address

Question 14

Front-end technology

Answer 14

• HTML
• CSS
• JavaScript

Question 15

Back-end technologies

Answer 15

• server-side languages: Python, JavaScript, Ruby
• Web-servers
• APIs

Question 16

Database management

Answer 16

• CRUD (Create, Read, Update, Delete)
• SQl
• NoSQL (MongoDB)

Question 17

RESTful API architecture

Answer 17

Styled for designing networked applications.
Stateless, resource-based interactions

Question 18

Deployment

Answer 18

• ensures app is accessible, scalable, secure and has high performance.

Question 19

Deployment environments

Answer 19

• development: Local machines, write and test code
• production: live and accessible to users
• staging: replica of production used for full-scale testing

Question 20

Deployment models

Answer 20

• on premises: app hosted on physical servers by organisation
• cloud-based: hosted on cloud services, offering scalability and reduced overhead
• hybrid: combo of both

Question 21

Deployment costs

Answer 21

• initial: setup including server or cloud-services
• ongoing: maintenance, scaling and monitoring
• optimisation: Auto-scaling and pay-as-you-go methods

Question 22

Metrics

Answer 22

Response time
latency
throughput

Used to analyse performance of good apps

Question 23

Scaling and performance

Answer 23

Types of scaling: Horizontal (more machines), Vertical (increase power of machines)

Performance optimisation: caching, load balancing (distributed load across two or more server)