Aditya kumar
Last Updated: May 13, 2022


REST (Representational State Transfer) is an architectural paradigm for establishing web services that define a set of requirements. REST API is a straightforward and flexible approach to accessing online services without going through any processing.

Because REST utilizes less bandwidth, is simple, and adaptable, it is recommended over the more robust Simple Object Access Protocol (SOAP) technology. It's used to retrieve or send data from a web service. Only HTTP requests are used in all REST API communication.


What is an API?

API stands for Application Programming Interface. It is a set of definitions and protocols for creating and integrating software applications. It's sometimes referred to as a contract between an information supplier and an information user, outlining the content that the consumer (the call) must offer and the producer’s content (the response). For example, the API design for a weather service could require the user to provide a zip code and the producer to respond with a two-part response, the first of which is the high temperature and the second of which is the low temperature.

In other words, if you want to connect with a computer or system to retrieve information or execute a function, an API allows you to convey your request to the system so that it can comprehend and respond.

An API can be considered a middleman between users or customers and the resources or web services they want. It's also a mechanism for a company to exchange resources and information while retaining security, control, and authentication—the ability to govern who has access to what.

                                                                                              Source: API Design


How do REST APIs Work?

It's crucial to understand resources to understand how REST APIs work. Any information that can be named, such as a document or image, a collection of other resources, a non-virtual object, and so on, can be considered a resource. On the other hand, REST uses a resource identifier to identify the individual resource engaged in component interaction.

The method refers to the kind of request you make to the server. The following are the five main resource methods connected with REST APIs:


To read (or get) a representation of a resource, use the GET method. The safe path produces an XML or JSON representation with an HTTP response code of 200. (OK). It usually produces a 404 (NOT FOUND) or 400 (Issue) code in the event of an error (BAD REQUEST). To obtain hello.htm, the following example uses the GET method:

GET /hello.htm HTTP/1.1

User-Agent: Mozilla/4.0 (compatible; MSIE5.01; Windows NT)


Accept-Language: en-us

Accept-Encoding: gzip, deflate

Connection: Keep-Alive



To create new resources, the POST verb is frequently used. It's utilized to make subordinate resources in particular. That is, it is subservient to another resource (for example, a parent). Return HTTP status 201 on successful creation, along with a Location header containing a link to the newly created resource with the 201 HTTP status. The following example uses the POST method to deliver form data to the server, which is then processed by the process.cgi and returned as a response:

POST /cgi-bin/process.cgi HTTP/1.1

User-Agent: Mozilla/4.0 (compatible; MSIE5.01; Windows NT)


Content-Type: text/xml; charset=utf-8

Content-Length: 88

Accept-Language: en-us

Accept-Encoding: gzip, deflate

Connection: Keep-Alive



It's utilized to keep the capabilities up to date. On the other hand, PUT can be used to create a resource when the client chooses the resource ID rather than the server. In other words, if the PUT is to a URI with the value of a resource ID, that does not exist. Return 200 (or 204 if no content is returned in the body) from a PUT after a successful update. Return HTTP status 201 on successful creation when using PUT. The following example instructs the server to save the specified entity-body in the server's root directory, hello.htm:

PUT /hello.htm HTTP/1.1

User-Agent: Mozilla/4.0 (compatible; MSIE5.01; Windows NT)


Accept-Language: en-us

Connection: Keep-Alive

Content-type: text/html

Content-Length: 182



It's used to get rid of a resource with a URI. Return HTTP status 200 (OK) and a response body upon successful deletion. The following example asks the server to delete the file hello.htm from the server's root directory:


DELETE /hello.htm HTTP/1.1

User-Agent: Mozilla/4.0 (compatible; MSIE5.01; Windows NT)


Accept-Language: en-us

Connection: Keep-Alive



It's used to change the capabilities. The PATCH request simply has to include the resource's changes, not the entire resource. This is similar to PUT, except the body contains a series of instructions indicating how to modify a resource currently on the server to create a new version. This indicates that the PATCH body should be written in a patch language like JSON Patch or XML Patch, rather than merely a modified section of the resource. An example for using the PATCH method is given below:

PATCH /file.txt HTTP/1.1


Content-Type: application/example

If-Match: "e0023aa4e"

Content-Length: 100


                                                                       Source: Working with REST API


What is the Difference between REST APIs and SOAPs?

                                           Source: SOAPvsREST


SOAP and REST APIs are not comparable in any way. However, there are a few items to consider below that will help you pick between these two web services. Here are several examples:

  • REST stands for REpresentational State Transfer, and SOAP is for Simple Object Access Protocol.
  • Because SOAP is a protocol, it adheres to tight guidelines to allow communication between the client and the server. In contrast, REST is an architectural style that does not comply with any set of guidelines but does adhere to six limitations outlined by Roy Fielding in 2000. The limitations include Uniform Interface, Client-Server, Stateless, Cacheable, Layered System, and Code on Demand.
  • SOAP is limited to XML for transmitting information in its message format, whereas REST is not. It is up to the implementer to decide which Media-Type to use, such as XML, JSON, or plain-text. Furthermore, REST can use the SOAP protocol, but SOAP cannot make use of REST.
  • SOAP employs @WebService for service interfaces to business logic, whereas REST uses URIs like @Path instead of interfaces.
  • SOAP is complex to implement and consumes more bandwidth, but REST is simple to implement and consumes less bandwidth, making it ideal for mobile devices.
  • SOAP provides several advantages over REST, one of which is that SOAP transactions are ACID compliant. Some applications demand transactional capability, which SOAP provides, but REST does not.
  • SOAP uses SSL (Secure Socket Layer) and WS-security for security, whereas REST uses SSL and HTTPS. SOAP is favored over REST for dealing with bank account passwords, credit card numbers, and other sensitive information. The security issue is that it depends entirely on your application's requirements; you must implement security on your own. It all comes down to the protocol you choose.

Source: Example of SOAP and REST


What is the purpose of REST APIs?

One of the main advantages of REST is that it offers a great deal of freedom, allowing you to accomplish more with this API. REST APIs can be used for a variety of things, as shown below:

Cloud applications

Because REST API calls are stateless, they are valuable in cloud applications. Stateless components can effortlessly redeploy and scale to suit load changes if something goes wrong.

Cloud services

Because you'd need to manage how the URL is decoded to bind to a service through an API, REST is also helpful in cloud services. Cloud computing and microservices, on the other hand, will surely make RESTful API design the norm in the future.

Web use 

These APIs can be accessed from a client-side web project, an iOS app, an IoT device, or a Windows Phone because REST is not bound to client-side technologies. You may develop the infrastructure for your company without having to worry about being bound to a specific client-side stack.


The Advantages of REST APIs

For a variety of reasons, REST is preferred over SOAP. REST APIs have the following advantages:

  • Scalability: The product may easily be grown by development teams due to the separation of client and server.
  • Flexibility and Portability: It is feasible to migrate from one server to another since REST-style APIs require data from one of the requests to be sent successfully. It is also possible to make updates to the database at any point in time.
  • Independence: The protocol's separation of client and server makes it easier for different parts of a project to develop separately. REST APIs are also adaptive to the working syntax and platform, allowing for simultaneous testing of many settings while building.


Architectural Constraints of REST API

The following are six architectural constraints that each web service must adhere to:

  • Uniform Interface
  • Stateless
  • Cacheable
  • Client-Server
  • Layered System
  • Code on Demand

Uniform Interface: Multiple architectural constraints are necessary to control the behavior of components to achieve a unified interface. Furthermore, resources should be distinct so that a single URL can identify them.

Stateless:  The information needed for the server to interpret and process the request from the client must be included in the request. The server is unable to store any information about the client's current state.

Cacheable: Cacheable and non-cacheable data must be identified in response to a request.

Client-Server: The consistent interface distinguishes between user and data storage concerns. The client's domain is concerned with user interface and request collection, whereas the server's domain is concerned with data access, workload management, and security. Because the client and server are separated, each may be created and improved independently of the other.

Layered System: REST enables the creation of a hierarchical architecture. As a result, each component is unable to see beyond the layer with which it is communicating.

Code on Demand: There is greater client functionality with REST APIs because they download and execute code in applets or scripts. A server will frequently return a static representation of resources, such as XML or JSON. When necessary, servers can also communicate executable codes to the client.


Frequently Asked Question

1. What exactly do you mean by RESTful Web Services?
Web services that follow the REST architecture are known as RESTful web services. REST stands for Representational State Transfer and is implemented via the HTTP protocol (web protocol). These services are lightweight, offer maintainability and scalability, and facilitate communication across several applications written in various programming languages. They use request headers, request body, response body, status codes, and other methods to access resources on the server that the client requires via the web browser.

2. What is the difference between PUT and POST?
To ask the server to accept the enclosed entity as a subordinate of the existing resource defined by the Request-URI, use the POST method. This indicates that a child resource will be created under a collection of resources using the POST method.

On the other hand, the PUT method should be used to ask the server to save the enclosed entity under the Request-URI specified. The given entity will be regarded as a changed version of the existing resource if the Request-URI points to an existing resource on the server. As a result, calling the PUT method either creates a new resource or updates an existing one.

Another significant distinction between the two techniques is that PUT is idempotent, whereas POST is not. Calling the PUT method many times, for example, will create or update the same resource. Numerous POST requests, on the other hand, will result in the creation of the same resource multiple times.

3. What are the benefits of using REST web services?

The following are some of the benefits of REST web services:

  • Because it uses the HTTP protocol, the learning curve is minimal.
  • Text, XML, JSON, picture, and other data transport protocols are supported.
  • There is no contract between the server and the client, resulting in a loosely linked implementation.
  • REST is a simple protocol.
  • REST methods are simple to test in a browser.


Key takeaway

In this blog we learned REST API and working of REST APIs with the help of different requests GET, POST, PUT, PATCH etc. We also got to know about the advantages of REST API and its comparison with SOAP API. This blog was more or less a theoretical aspect covering which is really important to know any topic in detail.

 You can also check our article on Learn what is rest API in 10 minutes and Best Practices For Well-Designed REST APIs which will help you in clearing more concepts on REST API.


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