introduction

Question 1

make a simple HTTP request using the curl command and analyze the output.

curl -iX GET https://reqres.in/api/users/1

Answer 1

The server response has HTTP headers and a message body.

Response headers as key/value pairs

The first line is the HTTP status code

One of the keys is a content-type and has a corresponding value

One of the keys is a set-cookie and has a corresponding value

Question 2

Cookies are

Answer 2

a unique identification number that help us keep track of our activity on different web pages.

When you first visit the website, the server assigns the unique identification number to the client. After the cookie is set, the client will always request the server using the cooki

Question 3

The second part of the HTTP response is

Answer 3

the message body, which is in the JSON format.

Question 4

The curl command is a command-line tool used to transfer data to or from a server,

Answer 4

with the help of any of the supported protocols (HTTP, FTP, IMAP, POP3, SCP, SFTP, SMTP, TFTP, TELNET, LDAP or FILE)

Question 5

HTTP resources are identified and located on the network by

Answer 5

Uniform Resource Locators (URLs), using the Uniform Resource Identifiers (URIs) schemes HTTP and HTTPS.

Question 6

https://www.educative.io/explore

Answer 6

https – protocol ( Secure HTTP )
www – subdomain
educative.io – domain name
/explore – service end point

Question 7

HTTP methods are designed to enable communications between clients and servers. We will discuss the most commonly used HTTP methods in the next few lessons.

Answer 7

GET
POST
PUT
DELETE

Question 8

The GET method is used by the client to

Answer 8

fetch the data from the server.

Question 9

By default, curl requests the URL using the GET method. To request the specific URL using the POST, DELETE or PUT methods,

Answer 9

we have to use the -X right after the curl command and specify the name of a particular method.

Question 10

The output is a JSON response returned from the server for the requested specified resource.

Answer 10

A JSON format will have a key/value pair that represents the data enclosed by curly braces.

Question 11

Using the -X switch will just show us the

Answer 11

HTML content in the form of the message body.

Question 12

The -iX switch will show us a

Answer 12

response header as well as HTML content in the form of the message body

Question 13

the -I switch will just show us

Answer 13

the response header.

Question 14

The HTTP POST method sends data to the server to

Answer 14

create a new resource.

Question 15

curl -iX POST -H “Content-Type: application/json” -d ‘{ “email”: “eve.holt@reqres.in”, “password”: “pistol” }’ https://reqres.in/api/register

Answer 15

-iX is for HTTP Method

-H is short for –header

-d for –data

Question 16

The HTTP PUT method will

Answer 16

update an existing resource or create a new resource on the server, (depending on the request payload.)

Question 17

curl -X PUT -d ‘{“title”:”This is an updated post”}’ https://jsonplaceholder.typicode.com/posts/1

Answer 17

-X is for HTTP Method
-d for –data

Question 18

The HTTP DELETE method

Answer 18

deletes the specified resource on the server.

Question 19

The response of DELETE request is empty { } JSON and the HTTP response status code is 204 OK. which means

Answer 19

that the resource is deleted

Question 20

HTTP requests are

Answer 20

messages sent by the client to initiate an action on a resource identified by a given URL over the network

Question 21

The components of an HTTP request are as below

Answer 21

The method to be applied to the resource – an HTTP method (like GET, PUT, POST HEAD or OPTIONS)

The resource identifier – resource identified by a given request URL.

Headers (optional) – headers are the information sent to the server in the form of key/value pairs, which contains the details of what the browser wants and will accept from the server.

Params (optional) – used for sending additional data to the server. For example, a query parameter.

Message body (optional) – These are additional information required by the server to process current requests properly. For example, a file type of JSON or XML sent in the case of a POST or PUT method request.

Question 22

After receiving and processing an HTTP request message, a server responds with

Answer 22

an HTTP response message

Question 23

The response returned from the server may contains

Answer 23

A status-line ( contains HTTP version and HTTP Status code ) – HTTP/2 200

Headers – these are general, response, or entity fields.

Response message body – a message in the form of a JSON, which returns the data associated with the post (id =1 )

Question 24

In a server’s HTTP response, status codes indicate

Answer 24

whether a specific HTTP request has been successfully completed or an error has occurred.

Question 25

The HTTP response status codes are divided into 5 categories

Answer 25

1xx: informational 2xx: success 3xx: redirection 4xx: client error 5xx:server error

Question 26

200 OK

Answer 26

The request has succeeded.

Question 27

201 Created

Answer 27

The request has been fulfilled and a new resource has been created.

Question 28

202 Accepted

Answer 28

The request has been accepted for processing, but the processing has not been completed.

Question 29

204 No Content

Answer 29

The request has succeeded and there is no content for the response message body.

Question 30

301 Moved Permanently

Answer 30

The target resource has been assigned a new permanent URI and any future references to this resource ought to use one of the enclosed URIs.

Question 31

302 Found

Answer 31

The target resource resides temporarily under a different URI.

Question 32

400 Bad Request

Answer 32

The server cannot process the request due to a bad/invalid request from a client (e.g., malformed request syntax, invalid request message framing, or deceptive request routing).

Question 33

401 Unauthorized

Answer 33

The request lacks valid authentication credentials for the target resource.

Question 34

403 Forbidden

Answer 34

There is an authorization error on the server.

Question 35

404 Not Found

Answer 35

The origin server did not find a current representation for the target resource.

Question 36

500 Internal Server Error

Answer 36

The server encountered an unexpected condition.

Question 37

502 Bad Gateway

Answer 37

The server, while acting as a gateway or proxy, received an invalid response from an inbound server it accessed while attempting to fulfill the request.

Question 38

503 Service Unavailable

Answer 38

The server is currently unavailable to handle the request.

Question 39

504 Gateway Timeout

Answer 39

The server, while acting as a gateway or proxy, received an invalid response from an inbound server it accessed while attempting to fulfill the request.

Question 40

What are HTTP headers?

Answer 40

basically a key-value, where its key is a case-insensitive string and value is a single or array of string. to pass some additional information through a request or a response.

Question 41

Types of HTTP headers

Answer 41

General headers Request headers Response headers Entity headers

Question 42

General headers

Answer 42

used for both request and response and there is no relation to the message data

Question 43

Request headers

Answer 43

client headers, sent during the HTTP request and they contain information about the resource to be fetched.

Question 44

Response headers

Answer 44

server headers and are part of the HTTP response. They give more details about the server resource context.

Question 45

Entity headers

Answer 45

these headers give meta-information about the content of the body of the message like MIME type, Content-length, etc.

Question 46

-I options in the curl command.

Answer 46

show only response headers from the web server in the form of key/value pairs. There will be no response message body shown

Question 47

What are HTTP parameters?#

Answer 47

When a client uses the HTTP GET method to request a certain resource from the web server, the client may also send certain parameters through the requested URL in the form of a query parameter, path parameter, or a form parameter.

Question 48

Query parameter#

Answer 48

The query parameter is a name-value pair and is the part of a requested GET URL. curl -X GET https://reqres.in/api/users?page=2

Question 49

path parameter

Answer 49

part of a requested GET URL path curl -X GET https://reqres.in/api/users/2

Question 50

Form parameter#

Answer 50

In an HTTP POST request a certain piece of information is sent as a form parameter in the form of a name-value pair. The client sends the form parameters in the requested body in the format that the Content-Type header field specifies. curl -iX POST --form "note=test" --form upfile=@sample.txt "content-type: multipart/form-data" https://cgi-lib.berkeley.edu/ex/fup.cgi The HTTP response contains the headers and the file content in the HTML format.

Question 51

REST, or Representational State Transfer, is an

Answer 51

architectural design that defines a set of rules for creating web services that interact between systems.

Question 52

Web services that follow REST architecture are termed

Answer 52

‘RESTful web services’

Question 53

RESTful system consists of two major components:

Answer 53

A server that hosts the resources A client that connects to the server to fetch the resources

Question 54

REST uses HTTP or HTTPS to exchange data between client and server using

Answer 54

HTTP methods – GET, POST, UPDATE, DELETE, HEAD, PATCH, etc.

Question 55

benefit from the loose coupling between the server and the client when REST is followed

Answer 55

Simplicity Light-weight Architecture is similar to Web Scalability

Question 56

Simplicity benefit for REST architecture

Answer 56

REST web services are easy and simple to develop compared to SOAP web services

Question 57

Light-weight benefit for REST architecture

Answer 57

REST advocates simple communication with the server over HTTP that supports plain XML, JSON formats in comparison to SOAP which supports only XML

Question 58

"Architecture is similar to Web" benefit for REST architecture

Answer 58

developers who understand the web can easily understand and develop RESTful web services

Question 59

Scalability benefit for REST architecture

Answer 59

conversational state that allows us to easily add multiple instances of the components or application behind load balancers

Question 60

A RESTful service needs to comply with

Answer 60

the following 6 guiding constraints: Client–Server Stateless Cacheable Uniform Interface Layered System Code on-demand

Question 61

Client–Server constraints for a RESTful service

Answer 61

separation of concerns By following this principle, we can improve the: portability of the user interface across platforms scalability by simplifying the server component

Question 62

Stateless constraints for a RESTful service

Answer 62

each request from the client must be sent to the server with all the necessary information to understand the request

Question 63

Cacheable constraints for a RESTful service

Answer 63

cache constraints require that the data within a response to a request be implicitly or explicitly denoted as cacheable or non-cacheable If a response is cacheable, then a client cache is given the right to reuse that response data for later, equivalent requests. This allows us to minimize the network calls made to the server.

Question 64

Uniform Interface constraints for a RESTful service

Answer 64

It simplifies and decouples the architecture of the system, allows us to independently scale the components, and improve the interactions between components and other systems.

Question 65

Layered System constraints for a RESTful service

Answer 65

allows an architecture to be divided into a number of hierarchical layers or tiers by constraining each of the layer’s behavior such that each layer cannot access beyond the immediate layer with which they are interacting with.

Question 66

Code on-demand constraints for a RESTful service

Answer 66

REST allows client functionality to be extended by downloading executable scripts that can be executed on client-side

Question 67

The four architectural constraints that RESTful system should follow in order to have a uniform interface are:

Answer 67

resource identification manipulation of resources through representations self-descriptive messages hypermedia as the engine of application state (HATEOS)