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 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:
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
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These are additional instructions sent with the request. These might define the type of response required or the authorization details.
*Request Body
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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
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This is the main body of the response.
*Response Status codes
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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.
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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
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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.
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
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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
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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
*1. State and functionality are divided into distributed resources
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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
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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 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
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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
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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
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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
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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
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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
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