REST is an architectural style for building scalable web services that are simple, lightweight and focused on standards. The key aspects of REST include using a stateless, client-server protocol like HTTP with standard operations like GET, PUT, POST and DELETE. Resources are uniquely identified and encapsulated, and the interface is designed to be self-descriptive with hypermedia. This allows RESTful services to evolve independently of clients.

1. CORDOVA TRAINING
SESSION: 8 – REST API’S

2. INTRODUCTION
 REST stands for REpresentational State Transfer. REST is the software architectural
style of WWW.
 The advantages of using REST are:
 Performance
 Scalability
 Simplicity
 Visibility
 Portability
 Reliability

3. INTRODUCTION
 RESTful systems typically communicate over Hypertext Transfer Protocol (HTTP) with
the same HTTP verbs like GET, POST, PUT, DELETE etc.
 REST is not a standard but an architectural style.
 Most of the RESTful implementations make use of common standards such as HTTP,
URI, JSON, and XML.

4. ARCHITECTURAL CONSTRAINTS
 REST has the following architectural properties:
 Client–Server
 Stateless
 Cacheable
 Layered
 Uniform interface

5. CLIENT - SERVER
 The client–server model of computing is a distributed application structure that partitions
tasks or workloads between the providers of a resource or service, called servers, and
service requesters, called clients.
 A client requests a server's content or service function.
 A server host runs one or more server programs which share their resources with clients.

6. CLIENT - SERVER

7. STATELESS PROTOCOL
 A stateless protocol is a communications protocol that treats each request as an
independent transaction that is unrelated to any previous request.
 Each communication consists of independent pairs of request and response.
 A stateless protocol does not require the server to retain session information or status
about each communications partner for the duration of multiple requests.
 The stateless design simplifies the server design because there is no need to
dynamically allocate storage to deal with conversations in progress.

8. STATELESS PROTOCOL
 If a client session dies in mid-transaction, no part of the system needs to be responsible
for cleaning up the present state of the server.
 A disadvantage of statelessness is that it may be necessary to include additional
information in every request, and this extra information will need to be interpreted by the
server.
 Eg: Authorization headers

9. WEB CACHE
 A web cache is an information technology for the temporary storage (caching) of web
documents, such as HTML pages and images, to reduce bandwidth usage, server load,
and perceived lag.
 A web cache system stores copies of documents passing through it; subsequent
requests may be satisfied from the cache if certain conditions are met.

10. LAYERED SYSTEM
 A layered system is a system in which components are grouped/layered, in a hierarchical
arrangement, such that lower layers provide functions and services that support the
functions and services of higher layers.

11. UNIFORM INTERFACE
 The uniform interface constraint is fundamental to the design of any REST service.
 The uniform interface simplifies and decouples the architecture, which enables each part
to evolve independently.
 Individual resources are identified in requests, for example using URIs in web-based
REST systems.
 The resources themselves are conceptually separate from the representations that are
returned to the client.

12. UNIFORM INTERFACE
 For example, the server may send data from its database as HTML, XML or JSON, none
of which are the server's internal representation.

13. SEMATIC URL
 Semantic URLs, also sometimes referred to as clean URLs, RESTful URLs, user-friendly
URLs, or search engine-friendly URLs, are Uniform Resource Locators (URLs) intended
to improve the usability and accessibility of a website or web service.
 Such URL schemes tend to reflect the conceptual structure of a collection of information
and decouple the user interface from a server's internal representation of information.

14. SEMATIC URL
 Semantic URLs also do not contain implementation details of the underlying web
application.
 This carries the benefit of reducing the difficulty of changing the implementation of the
resource at a later date.

15. SEMATIC URL

16. THANK YOU