Node.js Theory

Question 1

What is a Web Server?

Answer 1

A system that listens for and responds to HTTP requests

Question 2

What to Web Servers typically respond to requests with?

Answer 2

• A web application with an interface (eg a HTML doc)
• A web service. These are resources (eg info on whether a user is registered with a site), commonly in JSON or XML format.

A single server can serve both applications and data.

Question 3

What is an API?

Answer 3

Application Programming Interface

A way of externally accessing resources made available by a web service

• Typically specify endpoints as URLs
• Interact with endpoints by making HTTP requests
• Requests and responses typically use XML or JSON

We can think of requests to endpoints as being like a function/method call

Question 4

Name the two key attributes of RESTful APIs

Answer 4

They are stateless

• APIs don’t depend on the server remembering previous interactions with the client
• Requests contain all info necessary to respond

Uniform Interface

• Endpoints provide availability to interact with some collection of resources through some appropriate noun (eg /movies at the end of a URL)
• When a client has a representation of a resource, it should have enough info to modify or delete it

Question 5

What are the 3 key features of Node.js?

Answer 5

Event driven execution
- When used properly, this allows for thousands of concurrent connections on a single thread

It is JavaScript
- This allows you to use the same language on both client and serverr

Node Package Manager

Question 6

Should you use Asynchronous Execution loops or Synchronous Execution loops? Why

Answer 6

Asynchronous

Need to use a non-blocking I/O, otherwise functions in the stack that take a long time to execute will block execution for all users

Question 7

Should you use the main thread for expensive computations?

Answer 7

No, never, and never synchronously wait for a response for some external system.

A function operating on the main thread blocks executions and makes the server unresponsive

Question 8

What is Express?

Answer 8

A web application framework for node

Allows you to build web applications and services in node

Question 9

How is data persistence maintained in a Node.js Server?

Answer 9

Node does not store data - it is designed to process HTTP requests.

Need to use a database for this

Question 10

What is MongoDB?

Answer 10

A document oriented database

Question 11

How is data stored in MongoDB?

Answer 11

Data is stored in a collection of JSON-like documents

It makes reading and writing from JS straightforward

The structure isn’t constrained - it can change within a collection from document to document