Top 20 RESTful Web Services Interview Questions and Answers

Master the concepts of RESTful API with real-world scenarios from these top RESTful Web Services Interview Questions and excel in your next interview confidently:

Web services are a very well-known term when we talk about exchanging some sort of data between multiple applications or software. Based on the client-server model, multiple software applications written in various languages can use these services, and also have the advantage of running on various platforms.

Likewise, REST, Representational State Transfer, is also based on a stateless client-server style architecture, which can be easily accessed over the network and is identified by URIs (Uniform Resource Identifier.

Quiz on RESTful Web Services Interview Questions to Test Your REST API Skills

This quiz on RESTful Web Services Interview Questions is ideal for API Developers, Backend Developers, and Full-stack Engineers preparing for any technical interview. Test your REST API knowledge with this simple quiz and excel in your upcoming interview.

Basic Interview Questions on RESTful Web Services

The main aim of describing the definition of Web services and REST above is to help you relate to the term ‘RESTful web services’ because RESTful web services are defined as web services that use the HTTP method and are based on the architecture of REST. It has useful features like high scalability and maintainability, the creation of APIs, etc.

Learn More => Flask Restful API

In this article, you will find a collection of questions and answers that will clear your basics and help develop a better understanding of the subject.

Also read:

• Top Web Services Interview Questions
• Top SoapUI interview questions

Let’s start.

Q #1) What is your understanding of what RESTful web services are?

Answer: Just like SOAP (Simple Object Access Protocol), which is used to develop web services by the XML method, RESTful web services use a web protocol, i.e., the HTTP protocol method. They have features like scalability, maintainability, help with multiple application communication built on various programming languages, etc.

RESTful web service implementation defines the method of accessing various resources that are required by the client, and he sends the request to the server through the web browser.

The important aspects of this implementation include:

• Resources
• Request Headers
• Request Body
• Response Body
• Status codes

Q #2) Name the protocol that is used by RESTful web services.

Answer: RESTful web services use the famous web protocol, i.e., the HTTP protocol. This serves as a medium of data communication between the client and the server. HTTP standard methods are used to access resources in a RESTful web service architecture.

Q #3) Explain the term ‘Addressing’ concerning RESTful WEB services.

Answer: Just like we require an address with a postal code to reach any person, in the same way, ‘Addressing’ locates resources that are present on the server to host web services. Usually, people do this with a URI, i.e., Unified Resource Identifier.

Q #4) Enlist features of RESTful web services.

Answer: Every RESTful web service should have the following features and characteristics that are listed below:

• Based on the Client-Server representation.
• Use of the HTTP protocol for performing functions like fetching data from the web service, retrieving resources, executing any query, etc.
• The communication between the server and client is performed through the medium known as ‘messaging’.
• Addressing resources available on the server through URIs.
• Based on the concept of statelessness, where every client request and the response are independent of each other, with complete assurance of providing the required information.
• Uses the concept of caching.
• Works on the uniform interface.

Q #5) Explain the messaging technique.

Answer: Messages are the mode of exchanging data for any type of communication to take place. In the same way, the HTTP protocol plays the role of message communication between the client and server through HTTP Request and Response methods. An

HTTP request is sent by the client, which contains information about the data, and in turn, receives HTTP Response from the server.

Messages are a collection of information about the data, i.e., Metadata.

Q #6) What are the core components of the HTTP request and HTTP response?

Answer: The core components under HTTP Request are:

• Verb: Includes methods like GET, PUT, POST, etc.
• Uniform Resource Identifier for identifying the resources available on the server.
• HTTP Version for specifying the HTTP version.
• HTTP Request header contains information about the data.
• HTTP Request body that contains the representation of the resources in use.

The core components under HTTP Response are:

• Request Code: This contains various codes that determine the status of the server response.
• HTTP Version for specifying the HTTP version.
• HTTP Response header contains the information about the data.
• HTTP Response body that contains the representation of the resources in use.

Q #7) Explain the term ‘Statelessness’ concerning RESTful WEB service.

Answer: In REST, ST itself defines State Transfer, and Statelessness means complete isolation. This means that the state of the client’s application is never stored on the server and is passed on.

In this process, the clients send all the information that is required for the server to fulfill the HTTP request that has been sent. Thus, every client requests, and the response is independent of the other, with complete assurance of providing the required information.

Every client passes a ‘session identifier’, which also acts as an identifier for each session.

Q #8) Enlist the advantages and disadvantages of ‘Statelessness’.

Answer: In the above question, we have understood the meaning of statelessness concerning client-server communication. Now, let us see some of its advantages and disadvantages.

Advantages:

• Every method required for communication is identified as an independent method, i.e., no other methods influence them.
• Any previous communication with the client and server is not maintained, and thus, the whole process is very much simplified.
• If any information or metadata used earlier is required in another method, then the client sends that information again with the HTTP request.
• The HTTP protocol and REST web service both share the feature of statelessness.

Disadvantages:

• In every HTTP request from the client, the availability of some information regarding the client state is required by the web service.

Q #9) Enlist some important constraints for RESTful web services.

Answer: Every constraint has positive and negative impacts, and to produce an overall architecture, there should be a balance between both of them.

Below are some important constraints for RESTful web services:

• There should be separate concerns for each server and client, which will help to maintain the modularity within the application. This will also reduce the complexity and increase the scalability.
• The client-server communication should be stateless, which means no previous information is used, and the complete execution is done in isolation. With failure, it also helps the client to recover.
• In client-server communication, the HTTP response should be cacheable so that when required cached copy can be used, which in turn enhances the scalability and performance of the server.
• The fourth constraint is the uniform interface, which allows client-server interaction to be easily understood. This constraint is further divided into four sub-constraints as:
  • Resource Identification
  • Resource Manipulation
  • Each message is easily understood and is self-descriptive.
  • Hypermedia is defined as text with hyperlinks, and when clicked, it moves to another application state.
• Client-server communication should be done on a layered system, and thus, the client should only know the intermediate level with which communication is being done.

Q #10) What is a ‘Resource’?

Answer: Just like the ‘Object’ instance, we have learned in Object Orient Programming Language, in the same way, ‘Resource’ is defined as an object of a type which can be an image, HTML file, text data, or any type of dynamic data. There are varieties of representation formats available to represent a resource.

Some most common resources are listed below:

• JSON
• YAML
• XML
• HTML

RESTful Web Services Interview Questions for Experienced

Q #11) Why proper representation of Resources is required?

Answer: Representation is very important because it determines the easy identification of resources. Proper representations of resources in the proper format allow the client to easily understand the format.

Q #12) Enlist some important points that should be kept in mind while designing resource representation for RESTful web services.

Answer: There are no restrictions on the format in which the resource representation is done, but just that the main requirement is that the format of the representation should be as per the client’s requirement.

A good resource representation is designed by considering the following main points:

• The client and server should easily understand the resource representation format.
• The representation should be complete regardless of its format structure, which may be complex or simple.
• In the case of linking the resources to other resources, such cases should also be considered and handled.

Q #13) What is Caching?

Answer: Caching is the process by which a server response is stored so that a cached copy can be used when required, and there is no need to generate the same response again.

This process not only reduces the server load but in turn increases the scalability and performance of the server. Only the client can cache the response, and that too for a limited time.

Mentioned below are the headers of the resources and their brief descriptions so that they can be identified for the caching process:

• Time and date of resource creation
• Time and date of resource modification which usually stores the last detail.
• Cache-control header
• Time and date at which the cached resource will expire.
• The age determines the time from which the resource has been fetched.

Q #14) Explain Cache-Control header.

Answer: A standard Cache-Control header can help in attaining cacheability. Enlisted below is a brief description of the various cache-control headers:

• Public: Any intermediate components between the client and the server can cache resources that are marked as public.
• Private: Resources that are marked as private can only be cached by the client.
• No cache means that a particular resource cannot be cached, and thus, the whole process is stopped.

Q #15) What are the best practices that are to be followed while designing RESTful web services?

Answer: To design a secure RESTful web service, there are some best practices or say points that should be considered.

These are explained:

• Every input on the server should be validated.
• Input should be well-formed.
• Never pass any sensitive data through the URL.
• For any session, the user should be authenticated.
• Only HTTP error messages should indicate any fault.
• Use a message format that is easily understood and is required by the client.
• Unified Resource Identifier should be descriptive and easily understood.

Q #16) What is Payload?

Answer: The request data, which is present in the body part of every HTTP message, is referred to as ‘Payload’.  In the RESTful web service, the payload can only be passed to the recipient through the POST method.

There is no limit to sending data as payload through the POST method, but the only concern is that more data will consume more time and bandwidth. This may consume much of the user’s time, also.

Q #17) Enlist some of the HTTP methods with descriptions.

Answer: Listed below are the list of HTTP methods with their descriptions:

• GET: This is a read-only operation that fetches the list of users on the server.
• PUT: This operation is used for the creation of any new resource on the server.
• POST: This operation is used for updating an old resource or for creating a new resource.
• DELETE: As the name suggests, this operation is used for deleting any resource on the server.
• OPTIONS: This operation fetches the list of any supported options of resources that are available on the server.

Q #18) What is the difference between the PUT method and the POST method?

Answer: The major difference between the PUT and POST methods is that the result generated with the PUT method is always the same, no matter how many times the operation is performed. The result generated by the POST operation is always different every time.

Q #19) What is your understanding of JAX-RS?

Answer: JAX-RS is defined as the Java API for RESTful web services. Among multiple libraries and frameworks, this is considered the most suitable Java programming language-based API that supports RESTful web services.

Some implementations of JAX-RS are:

• Jersey
• RESTEasy
• Apache CFX
• Play

Among these, Jersey is the most popular framework.

Q #20) What are HTTP status codes? Enlist a few with meaning.

Answer: HTTP status codes are the representation of the status of the task that has been performed on the server, with the mode of some codes. Every code has its meaning.

Some of the HTTP status codes with their meaning are:

• Code 200: This indicates success.
• Code 201: This indicates the resource has been successfully created.
• Code 204: This indicates that there is no content in the response body.
• Code 404: This indicates that there is no method available.

A few more such codes indicate the status.

Conclusion

This article will help you prepare for the RESTful web services interview and help you understand the concept simply and easily. I have tried to cover all the areas that are very necessary for having complete knowledge about RESTful Web services.

Further Reading => Flask API Tutorial

Just remember, it may be possible that you are not able to answer all the questions in the interview, but whatever you answer should be accurate. Your basic concept should be strong, and your confidence level should be high.