RESTFUL VS RESTless API

API (Application Program Interface) is a mediator between two software or application databases, enabling them to communicate. For instance, when we order food using Swiggy, the matter requires location access from Google Maps and payment integration with PayPal, MasterCard, Visa and UPI.
API can be used in weather and music apps, telegram bots, and music apps. It gives a quick and seamless response. It is gaining its popularity. It gives advantage to our app as seamless, secure, efficient and easy to implement. In addition to security, developers can strengthen their security by leveraging signatures, tokens, and transport layer security (TLS) encryption.

What is web services?

Web services represent client and server applications, which use Hypertext Transfer Protocol (HTTP) to communicate over the WWW. It illustrates the standards for data exchange between different applications or software programs running on various platforms and frameworks. When you forward an HTTP request to a URL with requirements, the service sends back the result as a response. Furthermore, a web service is platform-independent.
You can think of a web API as a gateway between clients and resources on the web, Clients and Resources.

What are RestFul and Restless Api?

Let's first discuss REST.
REST stands for Representational State Transfer.
REST was conceptualized to make the best use of HTTP. It performs actions based on transfer protocols such as HTTP-post, GET, PUT, and DELETE.

REST embodies the following three elements:

1. Transport (HTTP only)
2. Data exchange format(JSON popularly)
3. Service Definition (WADL/Swagger)

The functionality of Rest Services consists of No involvement of any inbuilt encryption, is stateless, Only uses a single protocol( HTTP), returns anything in the form of JSON and is capable of performing CRUD operations utilizing HyperText Transfer Protocol.

The following are some of the principles of the REST architectural style:
The uniform interface imposes four architectural constraints:

1. Requests should identify resources.
2. Clients have enough information in the resource representation to modify or delete the resource if they want to.
3. Clients receive information about how to process the representation further.
4. Clients receive information about all other related resources they need to complete a task.

Statelessness
In REST architecture, statelessness refers to a communication method in which the server completes every client request independently of all previous requests. Clients can request resources in any order, and every request is stateless or isolated from other requests.

Layered system
In a layered system architecture, the client can connect to other authorized intermediaries between the client and server, and it will still receive responses from the server. You can design your RESTful web service to run on several servers with multiple layers such as security, application, and business logic, working together to fulfil client requests. These layers remain invisible to the client.

Cacheability
RESTful web services support caching by allowing API responses to define themselves as cacheable or noncacheable. This helps improve server response time by enabling clients and intermediaries to store and reuse responses, reducing the need for redundant data transfers.

Code on demand
In the REST architectural style, servers can temporarily extend or customize client functionality by transferring software programming code to the client.
.
**

What is REST API? How do RESTful APIs work?

**
A REST API (Representational State Transfer Application Programming Interface) is a set of rules and conventions for building and interacting with web services. It uses HTTP methods (such as GET, POST, PUT, and DELETE) to perform CRUD (Create, Read, Update, Delete) operations on resources (e.g., data objects) over the internet.

The basic function of a RESTful API is the same as browsing the internet. The client contacts the server using the API when it requires a resource. API developers explain how the client should use the REST API in the server application API documentation.

These are the general steps for any REST API call:

1. The client sends a request to the server. The client follows the API documentation to format the request in a way that the server understands.
2. The server authenticates the client and confirms that the client has the right to make that request.
3. The server receives the request and processes it internally.
4. The server returns a response to the client. The response contains information that tells the client whether the request was successful. The response also includes any information that the client requested.
5. The REST API request and response details vary slightly depending on how the API developers design the API.

The Main Components of Rest API are:

**_Unique resource identifier:**_ For REST services, the server typically performs resource identification using a Uniform Resource Locator (URL). The URL is also called the request endpoint and clearly specifies the server what the client requires.

**Method
**Developers often implement RESTful APIs using the Hypertext Transfer Protocol (HTTP). An HTTP method tells the server what it needs to do to the resource. The following are four HTTP methods: GET, POST, DELETE, and PUT.

HTTP headers
Request headers are the metadata exchanged between the client and server. For instance, the request header indicates the format of the request and response, provides information about the request status, and so on.

Data
REST API requests might include data for the POST, PUT, and other HTTP methods to work successfully.

Parameters
RESTful API requests can include parameters that give the server more details about what needs to be done.

**

What is RESTLESS API? How do RESTLESS APIs work?

**
RESTless web service or API does not adhere to the REST principles. It follows SOAP (an acronym for Simple Object Access Protocol). Unlike the RESTful API, the RESTless web service sends an XML request over the net using HTTP protocol and receives an XML response. Thus, SOAP or RESTless API is XML-based.

Every application sending SOAP requests contains a WSDL file that entails all the methods available in the web service. It also includes the types of requests and responses. In simple words, the WSDL file articulates the connection between the service and the client. Furthermore, it helps in communicating remote procedure calls to remote objects.

RESTless service is ideal for applications and software programs requiring security. However, it has certain constraints. It is comparatively slow and requires a greater amount of resources and bandwidth.
**

Why should you use RESTless API?

**

1. REST modeling presents a lack of schema
2. In certain cases, REST modelling can be unwieldy
3. Binary protocols offer greater efficiency than JSON
4. In a microservices realm, the number of services can grow significantly, each exposing multiple APIs.

Lack of schema in REST modelling/JSON poses a big integration challenge in such cases. Thus, in such a specific environment, it is always better to maintain a well-defined interface for every call.

Conclusion:

The primary difference between RESTful and RESTless API is that RESTful focuses on applications that follow the Representational State Transfer architecture while the RESTless API is an application that doesn’t follow the RESTful principle