Restful Web Services is a lightweight, manageable and scalable service based on the REST architecture. Restful Web Service exposes your application’s API in a secure, uniform, and stateless manner to the calling client.

1. What are Restful Web
Services?
Introduction
Restful Web Services is a lightweight, manageable and scalable service
based on the REST architecture. Restful Web Service exposes your
application’s API in a secure, uniform, and stateless manner to the
calling client.
Many use Restful architecture to create web-based APIs as I created for
a project, it is a Restful based News API that enables users to fetch and
download worldwide news data. Newsdata.io is the platform that I

2. am talking about, and you can check out the website and register to get
a free news API key.
The calling customer can perform predefined operations using the
Restful service. The underlying protocol for REST is HTTP.REST
stands for REpresentational State Transfer.
Key elements of REST
REST web services have come a long way since their inception. In
2002, the Web Consortium published the definition of WSDL and
SOAP web services. This formed the standard for implementing web
services.
In 2004, the Web Consortium also published the definition of an
additional standard called RESTful. Over the past two years, this
standard has become very popular. And it’s used by many of the
world’s most popular websites, including Facebook and Twitter.
REST is a means of accessing resources located in a particular
environment. For example, you might have a server that could host
important documents, pictures, or videos. These are all examples of
resources.
If a client, such as a web browser, needs any of these resources, it
should send a request to the server to access these resources. REST
services now define a way to access these resources.
The key elements of a RESTful implementation are as follows:

3. Resources
The first key element is the resource itself. Let assume that a web
application on a server has records of several employees.
Request Verbs
These describe what you want to do with the resource. A browser
issues a GET verb to indicate to the endpoint that it wants to get the
data. However, there are many other verbs available including POST,
PUT, and DELETE.
Request Headers
These are additional instructions sent with the request. These might
define the type of response required or the authorization details.
Request Body
Data is sent with the request. Data is normally sent in the request when
a POST request is sent to REST web services. In a POST call, the client
is actually telling REST web services that it wants to add a resource to
the server. Then the body of the request would have the details of the
resource that is to be added to the server.
Response Body
This is the main body of the response.

4. Response Status codes
These codes are the general codes that are returned along with the
response from the webserver. An example is code 200 which is
normally returned if there is no error when returning a response to the
client.
The following actions would have their respective meanings.
Suppose we have a RESTful web service defined in the location. When
the client makes a request to this web service, it can specify any of the
normal HTTP verbs of GET, POST, DELETE, and PUT. arrive If the
respective verbs have been sent by the client.
POST — Create a REST API resource.
GET — Retrieve information about the REST API resource.
PUT — Update a REST API resource.
DELETE — Delete a REST API resource or related component.
Why Restful
Restful mostly came into popularity due to the following reasons:
1. Heterogeneous languages and environments

5. This is one of the fundamental reasons which is the same we have also
seen for SOAP.
Allows web applications based on various programming languages to
communicate with each other.
Using Restful services, these web applications can reside in different
environments, some can be on Windows, others on Linux.
But in the end, no matter what the environment, the end result should
always be the same where they should be able to talk to each other.
Relying on web services provides this flexibility for applications built
on various programming languages and platforms to communicate
with each other.
The image below shows an example of a web application that should
communicate with other applications such as Facebook, Twitter, and
Google.
Now if a client app were to work with sites like Facebook, Twitter, etc.,
it would likely know what language Facebook, Google, and Twitter are
built on, as well as what platform they are built on.
Based on this we can write our web application interface code, but it
could turn out to be a nightmare.

6. Facebook, Twitter, and Google exhibit their functionality in the form of
Restful Web Services. This allows any client application to call these
web services through REST.
2. The event of Devices
Nowadays everything has to work on mobile devices, be it mobile
devices, laptops, or even car systems. Can you imagine the amount of
effort that goes into trying to code apps on these devices to
communicate with normal web apps? Again, Restful APIs can make
this job easier because, as mentioned in point n. 1, you don’t really
need to know what the underlying layer of the device is.
3. Finally is the event of the Cloud
Everything moves to the cloud. Applications are slowly moving to
cloud-based systems like Azure or Amazon. Azure and Amazon provide
many APIs based on the Restful architecture.
Consequently, applications must now be developed in such a way as to
be made compatible with the Cloud. Therefore, since all cloud-based
architectures work on the REST principle, it makes more sense for web
services to be programmed on the REST service-based architecture to
get the most out of cloud-based services.
Restful Architecture
An application or architecture considered RESTful or REST-style has
the following characteristics

7. 1. State and functionality are divided into distributed resources
This means that each resource must be accessible through the normal
HTTP commands of GET, POST, PUT or DELETE. So if someone
wants to get a file from a server, they need to be able to send the GET
request and get the file. If they want to put a file on the server, they
must be able to send the POST or PUT request, and finally, if they want
to delete a file from the server, they can send the DELETE request.
2. The architecture is client/server, stateless, layered, and supports
caching
Client-server is the typical architecture where the server can be the
webserver hosting the application and the client can be as simple as the
web browser.
Stateless means that the state of the application is not maintained in
REST. For example, if you delete a resource from a server using the
DELETE command, you cannot expect the deletion information to be
passed on to the next request.
To ensure that the resource is deleted, the GET request must be sent.
The GET request is used to first get all the resources on the server.
After that, you need to check if the resource has been deleted
successfully.
RESTFul Principles and Constraints
The REST architecture is based on certain characteristics which are
developed below. Any RESTful web service must meet the following

8. characteristics to be called RESTful. These features are also referred to
as design principles that should be followed when using RESTful-based
services.
1. RESTFul Client-Server
This is the fundamental requirement of a REST-based architecture.
This means that the server will have a RESTful web service that will
provide the requested functionality to the client. The client sends a
request to the web service on the server. The server would either reject
the request or comply and provide an adequate response to the client.
2. Stateless
The concept of a stateless state means that it is up to the client to
ensure that all requested information is provided to the server. This is
necessary for the server to correctly process the response. The server
should not keep any information between client requests. This is a very
simple, independent question-and-answer sequence.
The client asks a question, the server responds appropriately. The
customer will ask another question. The server will not remember the
previous question and answer scenario and will have to answer the new
question independently.
3. Cache

9. The concept of caching is to help with the stateless problem described
in the last point. Since each server-client request is independent in
nature, sometimes the client may request the same request from the
server again. This even if it was already required in the past. This
request will go to the server and the server will give a response.
This increases the traffic on the network. Caching is a concept
implemented on the client to store requests that have already been sent
to the server. So if the same request is given by the client, instead of
going to the server, it would go to the cache and get the requested
information. This saves the amount of round-trip network traffic from
the client to the server.
4. Layered System
The concept of a layered system is that any additional layer such as a
middleware layer can be inserted between the client and the actual
server hosting the RESTFul web service (the middleware layer is where
all the business logic is created.
This could be an extra service created that the client could interact with
before calling the web service.). But the introduction of this layer must
be transparent so as not to disturb the interaction between the client
and the server.
5. Interface/Uniform Contract

10. This is the technique behind how RESTful web services work. RESTful
basically works on the HTTP web layer and uses the following key
verbs to work with the resources on the
POST — To create a resource on the
GET — To retrieve a resource from the
PUT — To change the state of a resource or to update
DELETE — To delete or delete a resource from the server