Cloud computing and microservice technologies are trending and because of these, RESTful API has a bright future in the IT sector.
Many software enterprises prefer software developers with REST API skills. REST can help develop products that are scalable, easy to maintain, and make the products reach out to the world due to the power of the internet.
If you are preparing for interviews for a software developer or software QA profile, take a good understanding of the REST API concept.
Here, we have listed 20+ REST API interview questions and answers that a technical hiring manager may ask you.
Rest API Interview Questions Answers
What characteristics do RESTful Web Services have?
- The service makes use of the HTTP Protocol to fetch data from web services, run queries, and complete other tasks.
- To decrease server requests for the repetitive and same resource, it uses caching concept.
- The Client-Server model is the core of the service.
- It is based on the statelessness concept, client requests and answers are not dependent on others. This means there is a complete assurance to provide the required information.
What does the REST protocol mean by “statelessness”?
It means that the server does not keep track of the state of the client session. Whenever the client makes an HTTP request then all the necessary information should be included for the server to complete the request.
However, the client-provided context is used by the server to address requests made by the client.
The client also communicates the session identifier to the server. As a result, we can use a session identifier to determine which session is currently active on the server.
What are the different HTTP methods supported by REST?
Several HTTP Methods are demonstrated below:
GET: The GET method, which is essentially a read-only operation, is used to retrieve information from the server.
POST: This method is used for creating data.
PUT: The resource can be replaced or updated using this technique on the server.
DELETE: To delete a resource from a server using this method.
PATCH: This procedure partially changes or partially updates a server resource.
OPTIONS: This retrieves the list of information on the server for a resource to know the available communication options.
The terms POST, GET, PUT, and DELETE stand for creating, read, update, and delete operations, often known as CRUD Operations.
What is the difference between SOAP and REST?
- REST – REST stands for Representational State Transfer, SOAP – Simple Object Access Protocol
- In contrast to SOAP, which is a protocol with precise specifications like XML messaging, REST is a set of rules or architectural patterns that allows for flexible implementation.
- REST works best with multiple formats such as XML, HTML, JSON, and plain text whereas SOAP only supports XML formats.
- As compared to REST, SOAP requires more bandwidth.
- REST can always use SOAP but SOAP can’t use REST.
- While offering built-in security and transaction compliance that meet many organizational demands, SOAP web services are bulkier as a result. In addition, many open APIs, including the Google Maps API, adhere to the REST standards.
What do you understand by URI?
URI designates a distinct resource that is part of the REST architecture. URI stands for Uniform Resource Identifier, a unique pattern of characters that identifies the physical and logical resources such as people, places, information, and any real-world objects through web pages.
Below is an example of a URI format:
<protocol>:/<service-name>/<ResourceType>/<ResourceID>
There are two main varieties of URI in the REST protocol:
URL
Uniform Resource Locator is the term’s full form. A URL, as its name suggests, contains details about how to get a resource from its location. URL identifies the resource and also specifies its location and accessible process. A URL includes a network hostname, a protocol—such as FTP, HTTP, etc.—and a route to the particular web page.
URN
The term “URN” stands for “Uniform Resource Name.” A resource’s name can be used to identify it thanks to URN. The names of resources, however, are distinctive and enduring.
What is the difference between REST API and WebSocket?
- In contrast to REST, which is focused on CRUD operations, WebSocket is a low-level protocol built on the ideas of socket and port, which serve as the underlying transport mechanism.
- In contrast to REST, it is based on a stateless protocol and does not store data whereas WebSocket is based on stateful protocol and stores data.
- REST is uni-directional (either client or server can communicate) and WebSocket is bi-directional (both client and server can send and receive messages).
- In REST, a new TCP connection is created for each HTTP request. In WebSocket, only a single TCP connection is enough.
Give examples of some best practices for naming URIs for RESTful Web Services.
Some of the top advice for creating URIs for web services includes the following:
- When defining resources on the server, use plural names exclusively.
- Resource names should not be separated by spaces.
- A URI should always be given a lowercase name.
- Always avoid special characters
- Separate words with hyphens
What are the benefits and drawbacks of statelessness?
Pros–
- The entire communication process in the REST architecture is straightforward due to not storing the previous session between the REST client and REST server.
- It doesn’t require managing and storing the client’s previous action, which simplifies the application design.
- RESTful Web Services provided seamless integration with HTTP protocols, as HTTP is also stateless.
Cons–
- Every time the REST client responds to an HTTP request, the web service needs more amount of information about the client’s status.
- No previous record maintained
Specify what Payload is?
Every HTTP message’s body contains the request data known as the payload. In contrast, the HTTP POST method just allows the recipient to get the payload. The POST method also allows us to transmit an unlimited number of messages as payloads.
The only drawback is that processing more data takes longer due to faster bandwidth requirements.
RESTful Web Services testing – how to do it?
Postman is the subsequent testing tool. In Google Chrome, it functions as a plugin. Moreover, it is one of the most durable HTTP clients for web service testing. We can send queries to endpoints using Postman and get JSON or XML replies in return.
Why are REST services so simple to scale?
Statelessness is a principle that REST services adhere to, which effectively means that no need to manage data or sessions on the server of a request. As a result, it is simpler to scale horizontally because less communication between servers is required to fulfill requests.
Explain the REST architecture’s OPTION
With OPTIONS in RESTful Web Services, the client can choose which of the following HTTP Method to utilize for a resource identified by the Uniform Resource Identifier (URI).
- DELETE
- HEAD
- GET
- POST
- PUT
Apart from this, we can use options in the REST architecture to start a Cross-Origin Resource Sharing (CROS) request.
Explain caching.
Caching is the process of saving a REST service response. When necessary, we can use this cached copy.
As a result, caching eliminates the need to generate the same response repeatedly.
Additionally, the caching procedure improves server performance and lightens the load. Only the REST client can cache the response.
What are safe and idempotent HTTP methods?
The safe HTTP method doesn’t change the state of the server. You can implement this on read-only operations.
Examples of safe HTTP methods are OPTIONS, GET, HEAD, and TRACE.
Idempotent methods don’t change the outcome of a request despite being sent more than once.
Examples of idempotent HTTP methods are OPTIONS, GET, HEAD, TRACE, PUT & DELETE
POST & PATCH are neither safe nor idempotent HTTP methods.
Justify JAX-RS.
The full name of JAX-RS is Java API for RESTful Web Services. Strong support for building RESTful Web Services is provided by this Java-based programming language API. JAX-RS 3.0 is the most recent version released in June 2020. The creation of Web Services is quick and easy with JAX-RS thanks to Java SE 5’s annotations.
Can we use TLS (transport layer security) with REST?
Yes, we can use TLC with REST. TLS gives the capability to authenticate the server to the client and manages the task of encrypting communication between the REST client and the server.
It’s crucial to note that REST inherits the characteristics of the protocols it implements. Security precautions, therefore, depend on the protocol that REST uses.
How do you create a REST resource?
Any material that is a part of REST architecture is known as a REST Resource.
The REST architecture, for instance, allows the use of resources like HTML pages, text files, documents, photos, etc.
In addition, by employing the corresponding Uniform Resource Identifier, we may uniquely identify a resource (URI). For instance, XML, JSON, HTML, and YAML are some examples of generic resources.
In terms of RESTful Web Services, define addressing.
Locating single or more resources that are present on the server is called addressing. It’s like an address including a postal code that helps us to reach a person’s location. It can be done with URI (Uniform Resource Identifier) for completing this task.
The URI’s default format is <protocol>://<application-name>/<ResourceType>/<ID>
Which web service you should use, SOAP or REST, depends on what criteria, exactly?
There is no exact answer for choosing between SOAP and REST. Both have their own pros and cons. Choose one according to your requirements. REST services have grown majorly because of their inherent simplicity, scalability, increased speed, improved performance, and support for numerous data formats. However, SOAP has its benefits as well. It has higher standards for security, addressing, etc.
Well, SOAP is the oldest technology so developers are going with REST.
If the resources have to be shared by several clients, should we make them explicitly thread safe?
No, there is no need to explicitly make them thread-safe as they are already safe by default. Every request produces a new resource instance that makes that thread safe.
What are the main security threats and challenges with web services?
Some of the major security threats and challenges with web services:
- Session Hijacking: A cyber-criminal can steal the user’s session token and get access to the resources.
- Message Injection: An attacker can inject new malicious messages between the client and the server or tweak messages.
What are the points to consider while creating resource representations?
There are no limits while creating a resource representations format. Still, you should follow some basic parameters while creating a representation format for a RESTful web service:
- Should be understood by client and server – A resource representation format should be understandable by both the server and the client end.
- Should be capable to complete a resource – It doesn’t matter resource has a simple or complex structure, a format should be able to represent a resource accurately and completely.
- Should have linkability – A format should be able to handle such situations where one resource links to another.
Hope, these questions and answers will assist you in preparing well for an interview to grab your dream job.
Stay confident!
Good luck!
