What REST Services Are

REST represents Representational State Transfer. REST is a web standards-based architecture and uses HTTP Protocol. It spins around assets where each part is a component and an asset is gotten to by a common interface utilizing HTTP standard strategies. REST was firstly presented by Roy Fielding in 2000. 

In REST architecture, a REST Server just gives access to assets and REST client gets to and modifies the assets. Here every asset is recognized by URIs/worldwide IDs. REST utilizes different representations to represent an asset like text, JSON, XML. JSON is the most famous one.

The following four HTTP methods are commonly utilized in REST-based architecture.

• GET         - Provide read-only access to a resource.
• POST       - Use to create a new resource
• DELETE  - Use to remove a resource.
• PUT          - Use to update an existing resource or create a new resource.

A web service is an assortment of open protocols and standards utilized for trading data between applications or frameworks. Software applications written in different programming languages and running on different platforms can utilize web services to trade over PC networks like the Internet in a way like inter-process communication on a single PC. This interoperability (e.g., among Java and Python, or Windows and Linux applications) is because of the utilization of open standards. 

Web services dependent on REST Architecture are known as RESTful web services. These web services utilize HTTP methods to execute the idea of REST architecture. A RESTful web service normally characterizes a URI, Uniform Resource Identifier a service, gives resource representation, for example, JSON and set of HTTP Methods.

RESTful Principles and Constraints

The REST architecture depends on a couple of characteristics that are explained below. Any RESTful web service needs to consent to the below characteristics with the end goal for it to be called RESTful. These characteristics are otherwise called design principles that should be followed when working with RESTful based services.

01 ) RESTful client-server 

This is the most major prerequisite of a REST-based architecture. It implies that the server will have a RESTful web service that would give the necessary functionality to the client. The client send's a request to the webserver on the server. The server would either dismiss the request for or go along and give a satisfactory response to the client.

02 ) Stateless

The idea of stateless implies that it's dependent upon the client to guarantee that all the required information is given to the server. This is required with the goal that the server can process the response appropriately. The server ought not to keep up any kind of information between requests from the client. It's a straightforward independent question-answer sequence. The client poses a question, the server answers it fittingly. The client will pose another question. The server won't recall the past question-answer situation and should address the new question independently.

03 ) Cache

The Cache idea is to help with the issue of stateless which was depicted in the last point. Since every server-client request is autonomous in nature, some of the time the client may approach the server for the same request once more. This is despite the fact that it had just requested it before. This request will go to the server, and the server will give a response. This builds traffic over the network. The cache is an idea executed on the client to store requests which have just been sent to the server. So if a similar request is given by the client, rather than heading off to the server, it would go to the cache and get the necessary data. This spares the measure of back and fro network traffic from the client to the server.

04 ) Layered System

The idea of a layered system is that any extra layer, for example, a middleware layer can be embedded between the client and the real server hosting the RESTFul web service (The middleware layer is the place all the business rationale is made. This can be additional service made with which the client could cooperate with before it makes a call to the web service.). In any case, the introduction of this layer needs to be transparent so it doesn't disturb the communication between the client and the server.

05 ) Interface Contract

This is the hidden system of how RESTful web services should work. RESTful basically works on the HTTP web layer and uses the underneath key action words to work with resources on the server 

• POST - To make resources on the server 
• GET   - To recover resources from the server 
• PUT   - To change the condition of resources or to update it 
• Erase  - To remove or erase a resource from the server