Here are top Rest API interview questions,
1. What is REST, and how does
it differ from SOAP?
REST,
which stands for Representational State Transfer, is an architectural style for
designing networked applications. It uses a stateless, client-server
communication model and is based on standard HTTP methods. SOAP (Simple Object
Access Protocol) is a protocol for exchanging structured information in the
implementation of web services. Unlike REST, SOAP is a protocol and not an
architectural style. REST is typically more lightweight and relies on URL
endpoints and standard HTTP, while SOAP uses XML and can be more complex.
2. Explain the main principles
of REST.
The
main principles of REST are:
- Statelessness: Each request from a
client to a server must contain all the information needed to understand and
process the request.
- Client-Server Architecture: The client
and server are separate entities that communicate over a stateless protocol.
-
Uniform Interface: A consistent and uniform way to interact with resources
using standard HTTP methods.
- Resource-Based: Resources are identified
by URIs and can be manipulated using standard HTTP methods.
- Representation: Resources can have
multiple representations (e.g., JSON, XML).
3. What are the commonly used
HTTP methods in REST, and what do they represent?
Common
HTTP methods in REST are:
- GET: Retrieve data from the server.
- POST: Create a new resource on the
server.
- PUT: Update an existing resource on the
server.
- DELETE: Remove a resource from the
server.
- PATCH: Partially update a resource.
4. What is an endpoint in a
REST API?
An
endpoint is a specific URI (Uniform Resource Identifier) that represents a
resource in a RESTful API. Clients use endpoints to interact with the server
and perform actions on the resource it represents.
5. What is the significance of
status codes in HTTP responses? Can you give examples of some common HTTP
status codes?
Status
codes in HTTP responses provide information about the result of a request.
Common status codes include:
-
200 OK: Successful request.
- 201 Created: Resource was successfully
created.
- 204 No Content: The request was
successful, but there's no response body.
- 400 Bad Request: The request was
malformed or invalid.
- 401 Unauthorized: Authentication is
required or failed.
- 404 Not Found: The requested resource
does not exist.
- 500 Internal Server Error: Something
went wrong on the server.
6. Explain the concept of
idempotence in REST.
Idempotence
means that making the same request multiple times has the same effect as making
it once. In REST, HTTP methods like GET and PUT are idempotent because they
don't change the server's state with repeated requests. For example, calling a
GET request multiple times should not have any side effects.
7. What is the purpose of the
"Accept" header in an HTTP request?
The
"Accept" header in an HTTP request specifies the media types that the
client can understand in the response. It allows the client to request data in
a specific format, such as JSON or XML. The server can use this header to send
an appropriate representation of the resource to the client.
8. Explain the concept of
content negotiation in REST.
Content
negotiation is the process of determining the format of the response data based
on the client's preferences. It's often done using the "Accept"
header in the request, allowing the server to send data in the preferred format
(e.g., JSON or XML) based on the client's requirements.
9. What is HATEOAS, and why is
it important in REST?
HATEOAS
(Hypermedia as the Engine of Application State) is a principle in REST that
suggests including hyperlinks in API responses, allowing clients to discover
and navigate to related resources dynamically. This makes the API
self-descriptive and reduces the need for hard-coded, prior knowledge of
resource URLs.
10. What is CORS, and why is it
important in REST APIs?
CORS
(Cross-Origin Resource Sharing) is a security feature that controls web page
access to resources from different domains. It's essential in REST APIs because
it ensures that web applications running in a browser can securely make requests
to different domains, preventing cross-site request forgery (CSRF) attacks.
11. What is the Richardson
Maturity Model, and how does it relate to REST?
The
Richardson Maturity Model defines four levels of RESTfulness, ranging from
Level 0 (the least RESTful) to Level 3 (fully RESTful). It helps assess how
well an API adheres to REST principles. Level 3 APIs, in particular, are fully
RESTful and support HATEOAS, making them self-descriptive and highly
discoverable.
12. How can you secure a REST
API against common security threats?
To
secure a REST API, you can implement various security measures, including
authentication (e.g., OAuth, API keys), authorization, using HTTPS, input
validation, output encoding, and protection against common security threats
like SQL injection, cross-site scripting (XSS), and cross-site request forgery
(CSRF).
13. What is versioning in REST,
and why is it important?
Versioning
in REST involves specifying the API version in the URL or headers. It is
essential to maintain backward compatibility when making changes to the API,
ensuring that existing clients can continue to function while accommodating new
features or modifications.
14. Explain the concept of rate
limiting in REST.
Rate
limiting is a technique used to control the number of requests a client can
make to an API within a specific time frame. It helps prevent abuse or overload
of the API by limiting the number of requests a client can send over a given
period.
15. What are the benefits of
using RESTful APIs over other architectural styles?
RESTful
APIs offer benefits such as simplicity, scalability, loose coupling between
client and server, ease of integration with various platforms and languages,
and compatibility with the stateless nature of the web. They are widely adopted
for web and mobile applications due to their lightweight nature.
16. What is the purpose of a
media type in REST, and can you provide examples?
A
media type, often specified using the "Content-Type" header,
indicates the format of the representation of a resource. Common media types
include "application/json" for JSON data and
"application/xml" for XML data. Media types help clients understand
how to interpret the response data.
17. What is the role of caching
in REST, and how does it improve performance?
Caching
in REST involves storing responses on the client side or intermediary caches.
It improves performance by reducing the need for repeated requests to the
server, thereby reducing latency and server load. Caching can be controlled using
HTTP caching headers like "Cache-Control."
18. What is the purpose of the
"OPTIONS" HTTP method in REST?
The
"OPTIONS" method is used to retrieve information about the
communication options for the target resource. It can be used to discover the
allowed methods, authentication requirements, and other details about a
resource without making an actual request.
19. Explain the difference
between REST and GraphQL.
REST
and GraphQL are both approaches to building APIs, but they have different
characteristics. REST uses predefined endpoints and fixed responses, while
GraphQL allows clients to request exactly the data they need, which can reduce
over-fetching or under-fetching of data. GraphQL provides more flexibility for
clients, while REST is more straightforward and has well-defined conventions.
20. How can you handle errors
and exceptions in a REST API?
Errors and exceptions in a REST API can be handled by using appropriate HTTP status codes (e.g., 4xx for client errors, 5xx for server errors), providing clear error messages in the response body, and following a consistent error format. Additionally, API documentation should include details about common error scenarios and how to handle them.
Above are few top Rest API interview questions. Remember to prepare and expand on these answers. Good luck with your interview! 👍
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