REST and JSON in Android

REST/RESTful

Introduction

• It is also called RESTful API.
• REST stands for Representational State Transfer (REST).

Definition

• RESTful API is a type of web service architecture that follows the principles of Representational State Transfer (REST).

Characteristic Features

• REST is an architectural style for designing networked applications.
• They are known for their simplicity, scalability, and ease of use, and the use of standard HTTP methods for communication making them a popular choice for modern web development.
• Characteristics of RESTful web services:

• • Statelessness:
    • RESTful services are stateless, meaning that each request from a client to the server must contain all the information needed to understand and process the request. There should be no server-side session state that the server relies on between requests.
  • Resources and URLs:
    • In REST, resources are represented as entities, and each resource is identified by a unique URL (Uniform Resource Locator).
    • Resources can represent data objects, such as users, products, or articles, and the URLs are used to access and manipulate these resources.
  • HTTP Methods:
    • RESTful services use standard HTTP methods to perform actions on resources.
    • The most commonly used HTTP methods in REST are:
      1. GET: Retrieve data from the server (read).
      2. POST: Create a new resource on the server.
      3. PUT: Update an existing resource on the server.
      4. DELETE: Remove a resource from the server.
  • Uniform Interface:
    • A uniform and consistent interface is a fundamental principle of REST.
    • Clients interact with resources using standard HTTP methods, and the structure of the URLs and the data format (usually JSON or XML) should be consistent and predictable.
  • Representation:
    • Resources can have multiple representations (e.g., JSON, XML, HTML) depending on client preferences.
    • The client specifies the desired representation in the HTTP Accept.
  • Stateless Communication:
    • Each request from the client to the server should be self-contained and not rely on previous requests or server-side state.
    • Authentication and session information can be included in the request headers.
  • Layered System:
    • REST allows for the use of intermediaries, such as proxy servers, load balancers, and caches, without affecting the overall system architecture. This supports scalability and performance.
  • Response Codes:
    • HTTP response codes (e.g., 200 OK, 404 Not Found, 500 Internal Server Error) are used to indicate the result of a request. They provide information about the success or failure of the request.
  • HATEOAS (Hypermedia as the Engine of Application State):
    • HATEOAS is a constraint in REST that suggests including hyperlinks in responses, allowing clients to navigate the API dynamically by following links provided in the resource representations.
  • Security:
    • RESTful APIs can use various security mechanisms, such as HTTPS for data encryption, authentication, and authorization mechanisms to protect resources.

Example

An example of a RESTful API endpoint is:

• • URL: https://api.example.com/users/123
  • HTTP Method: GET
  • Action: Retrieve user information for the user with ID 123.

Use/Application

• RESTful web services are widely used for building web and mobile applications, and various other distributed systems as well as for providing APIs for external developers to access and interact with data and services.