REST Web Services

REST stands for REpresentational State Transfer. It was created in 2000 by Roy Fielding in UC, Irvine.

It is an architectural style, and an approach to communications that is often used in the development of Web services.
It’s an arrangement of functions on which the testers performs requests and receive responses. In REST API communications between clients and servers are made through HTTP protocol.
REST also allows communication between one computer to computer other over a network.
For sending and receiving messages REST involves HTTP methods which does not require a strict message definition.
REST messages often accepts and return in the form of XML(EXtensible Markup Language) or JSON (JavaScript Object Notation ).
REST follows the ideology of the Open Web.
It is easy to implement and maintain as compared to SOAP.
It clearly separates client and server implementations
REST Information can be stored by the client to prevent multiple calls.
REST describes a set of architectural principles by which data can be transmitted over a standardized interface using HTTP.
REST allows better support for browser clients due to it’s support for JSON.
REST does not contains additional messaging layer.
It focuses on design rules for creating stateless services.

REST Workflow :

It’s four principles can explain the success and the scalability of the HTTP protocol implementing them
1. Resource identification through URI
2. It provides uniform Interface for all resources:
       GET (Query the state, idempotent, can be cached)
       POST (Update a resource or create child resource)
       PUT (Transfer the state on existing/new resource)
       DELETE (Delete a resource)
3. It has “Self-Descriptive” Message representations
4. Hyperlinks to define relationships between resources and valid state transitions of the service interaction

HTTP Verbs describe the type of operation:

Fig. : HTTP actions

GET: It is used to retrieve a resource
POST: It creates a new resource
PUT: It updates an existing resource
DELETE: It deletes an existing resource

Workflow of HTTP Verbs :

When to use REST:

When clients and server both operates on Web Environment, we should use REST.
When information about the object need not to be communicated to the client.

Advantages of REST API :

Communication is not controlled by a single entity.
clearly separates client and server implementations.
Information can be stored by the client to prevent multiple calls.
It returns data in multiple formats(JSON, XML)
It is easy to implement and maintain.

Dis-Advantages of REST API :

It works on the top of HTTP protocol.
It is hard to enforce authorization.
It has stateless existence.
It leverages a layered system and uniform interface
Security is on top of it.