6.5 REST-based APIs

Question 1

Define:

API Key

Answer 1

A unique identifier used to authenticate API requests.

API keys are commonly used to control access to public or private resources, and they help in tracking API usage.

Question 2

What is a RESTful API?

Answer 2

An interface using HTTP requests to perform CRUD operations.

REST stands for Representational State Transfer, emphasizing statelessness and a uniform interface.

Question 3

Define:

“statelessness” in RESTful APIs.

Answer 3

Each request must contain all required information.

The server doesn’t store session data, making the system scalable and easy to manage.

Question 4

What are the six attributes defined for REST APIs?

Answer 4

1. Client/server architecture
2. Stateless operation
3. Clear statement of cacheable/uncacheable
4. Uniform interface
5. Layered
6. Code-on-demand

Client/server architecture: Separation of client and server roles.

Stateless operation: Each request is independent and has all necessary information.

Clear statement of cacheable/uncacheable: Specifies which responses can be cached.

Uniform interface: Consistent interface for interaction across services.

Layered: Allows multiple layers of servers between client and server.

Code-on-demand: Server can provide executable code to the client.

Question 5

True or False:

REST APIs are always stateless.

Answer 5

True

Statelessness means the server doesn’t retain client session information between requests.

Question 6

Describe the concept of a resource in RESTful APIs.

Answer 6

It is any object or data accessed via a URI.

Resources can represent users, documents, or any entity that can be acted upon by HTTP methods.

Question 7

List two required attributes of a REST-based API.

Answer 7

1. Uses HTTP
2. Client/server architecture

Uses HTTP: RESTful APIs rely on the HTTP protocol for communication.

Client/server architecture: RESTful APIs maintain a clear separation between client and server.

Question 8

List the four primary HTTP methods used in REST APIs.

Answer 8

1. GET
2. POST
3. PUT
4. DELETE

GET: Retrieves data from the server without modifying any resource.

POST: Sends data to the server to create a new resource.

PUT: Updates an existing resource with new data.

DELETE: Removes a specified resource from the server.

Question 9

Why are HTTP verbs important in REST APIs?

Answer 9

They define the action on resources.

HTTP verbs play a crucial role in REST APIs by standardizing how clients interact with resources.

Question 10

How does the GET method work in REST APIs?

Answer 10

It retrieves data without modifying the resource.

GET is used to fetch data like user details or product information from the server.

Question 11

What are the four fundamental operations that a REST API can perform?

Answer 11

• Create
• Read
• Update
• Delete

Create: Adds new resources to the server.

Read: Retrieves existing resources from the server.

Update: Modifies existing resources on the server.

Delete: Removes resources from the server.

Question 12

True or False:

The DELETE method permanently removes a resource from the server.

Answer 12

True

DELETE is used to permanently delete the specified resource.

Question 13

Which HTTP verb corresponds to the CRUD action ‘Read’?

Answer 13

GET

The GET method is used to retrieve data from the server without modifying any resource. It is the standard method for reading data in RESTful APIs.

Question 14

True or False:

PUT and PATCH can be used interchangeably to update a resource.

Answer 14

False

PUT replaces the entire resource, while PATCH updates only the specified fields.

Question 15

What type of architecture do REST APIs use?

Answer 15

Client/server

Clients handle user interactions, while servers manage data storage and processing.

Question 16

Fill in the blank:

The HTTP verb used for updating an existing resource is ______.

Answer 16

PUT

PUT replaces an existing resource with a new version.

Question 17

Describe how the PATCH method works in REST APIs.

Answer 17

It partially updates a resource.

PATCH is used to apply updates to specific fields, unlike PUT which replaces the entire resource.

Question 18

Fill in the blank:

The HTTP verb for creating new data structures is ______.

Answer 18

POST

POST is used to create new resources on the server.

Question 19

Describe the role of authentication in REST APIs.

Answer 19

It ensures only authorized access to resources.

Common methods include Basic Authentication, OAuth, and API keys for securing API endpoints.

Question 20

Define:

Basic Authentication

in REST APIs

Answer 20

A method where the client sends base64-encoded credentials.

While easy to implement, it is considered insecure because the credentials can be easily decoded if intercepted. It’s often recommended to use it over HTTPS or opt for more secure authentication methods like OAuth.

Question 21

How does OAuth work as an authentication method in REST APIs?

Answer 21

It uses tokens to grant access without exposing credentials.

OAuth allows secure and delegated access to resources without sharing passwords.

Question 22

Why is data encoding important in REST APIs?

Answer 22

It ensures proper data transmission.

It maintains data integrity and supports content negotiation, allowing clients and servers to agree upon the data format (such as JSON or XML) for communication.

Question 23

What is the most commonly used data format in REST APIs?

Answer 23

JSON

(JavaScript Object Notation)

JSON is lightweight, easy to read, and supported by most web technologies.

Question 24

What type of data does a REST API typically return?

Answer 24

In text format, commonly as JSON.

REST APIs primarily return data in textual formats like JSON (JavaScript Object Notation) due to its lightweight nature and ease of use.

Question 25

# True or False: A RESTful API **always** uses JSON as its data format.

Answer 25

False ## Footnote While JSON is common, REST APIs can also use *XML, HTML, or other formats.*

Question 26

Why is XML **still used** in some REST APIs despite JSON's popularity?

Answer 26

It supports **more complex** data structures and attributes. ## Footnote **XML (eXtensible Markup Language)** offers *features* like a rich set of data types, support for namespaces, and a strict schema definition, which can be beneficial for representing complex data structures and ensuring data integrity.

Question 27

Describe the **role** of HTTP headers in REST APIs.

Answer 27

They carry metadata like **authentication** and **content-type**. ## Footnote **Headers** ensure that the server understands the request and responds accordingly.

Question 28

What is the **purpose** of URIs in REST APIs?

Answer 28

They **identify the specific resource** that the HTTP request acts on. ## Footnote **URIs (Uniform Resource Identifiers)** direct API requests to the correct resource for processing.

Question 29

Describe the **structure** of a URI used in a REST API call.

Answer 29

It **includes** the protocol, hostname/IP address, path (resource), and query parameters. ## Footnote The **URI** is crucial for routing API requests to the correct resource.

Question 30

How does **error handling** work in REST APIs?

Answer 30

REST APIs use **HTTP status codes** to indicate the result of an API request. ## Footnote *Status codes* such as 400 (Bad Request), 401 (Unauthorized), and 500 (Internal Server Error) help clients understand how the request was processed.

Question 31

# True or False: REST APIs **always return** a 200 status code for successful operations.

Answer 31

False ## Footnote *Different HTTP status codes* (like 201, 204, etc.) may be used to indicate success or the type of operation (e.g., creation, no content).

Question 32

What does the HTTP status code 404 **indicate** in a REST API response?

Answer 32

Not Found ## Footnote A *404 status code* means the requested resource could not be found on the server.

Question 33

How does **"Token-based Authentication"** work in REST APIs?

Answer 33

It uses tokens (e.g., JWT) to **authenticate** users. ## Footnote Token-based authentication *enhances security* by **avoiding** the need to transmit sensitive credentials and allows for single sign-on (SSO) across applications.