restifarian


A RESTifarian is a zealous proponent of the REST


REST


REpresentational State Transfer


Is an architectural style for distributed systems

Conforming to the REST constraints is generally referred to as being "RESTful"


rest

The key abstraction of information in REST is a resource. Any information that can be named can be a resource: a document or image, a temporal service (e.g. "today's weather in Ra'anana")

REST components perform actions on a resource by using a representation

Resource based

Things (resources) vs actions
=
Nouns vs verbs:
(GET) scheduler/channels - getSchedulerChannels();
Versus SOAP-RPC (Simple Object Access Protocol)
Identified by URIs
Multiple URIs (may) refer to the same resouce

Representations

A serialized description of a resource
Example:
  • Resource: channel (CNN)
  • Service: view meta data (GET)
  • Representation:
  • call-sign, alias, multicast feed, etc
  • JSON/XML format

HTTP

HTTP is a request/response protocol


request



response








http verbs

They mean something




rest constrains

  1. Uniform Interface
  2. Stateless
  3. Cache
  4. Client-Server
  5. Layered system
  6. Code on Demand

Uniform Interface

The uniform interface constraint defines the interface between clients and servers.  It simplifies and decouples the architecture, which enables each part to evolve independently

HTTP verbs (CRUD)

URIs (resource name)

HTTP response (status, body)



Statless

  1. Server contains no client state
  2. Each request contains enough context to process the message (self descriptive messages)
  3. Any session state is held on the client
  • Visibility
  • Reliability
  • Scalability

stateless

  1. Visibility is improved because a monitoring system does not have to look beyond a single request datum in order to determine the full nature of the request
  2. Reliability is improved because it eases the task of recovering from partial failures
  3. Scalability is improved because not having to store state between requests allows the server component to quickly free resources

Cache

As on the World Wide Web, clients/CDN can cache responses.

This gives us: The advantage of having the potential to partially or completely eliminate some interactions, improving efficiency


Each request must declare it's own caching rule:

  1. Implicitly
  2. Explicitly
  3. Negotiate



Client - server

  • Separation of concerns is the principle behind the client-server constraint.
  • By separating the user interface concerns from the data storage concerns, we improve the portability of the user interface across multiple platforms and improve scalability by simplifying the server components.
  • Components to evolve independently

layered system

A client does not need to know to whom it's connected.
By restricting knowledge of the system to a single layer, we place a bound on the overall system complexity and promote substrate independence

The primary disadvantage of layered systems is that they add 
overhead and latency to the processing of data.

Code on demand

(optional)

Servers are able to temporarily extend or customize the functionality of a client by transferring logic to it that it can execute.


The reply can be javascript file, java applet



response types

Generally using the HTTP status code to describe the result

1xx: Infomration (100: continute...)
2xx: Success (200:ok, 201: created...)
3xx: Redirection (301: moved permanently)
4xx: Client error (400: bad request, 404: not found...
5xx: Server error (500: internal error, 501: not impl...)


Examples

In the wild


Resources

http://www.ics.uci.edu/~fielding/pubs/dissertation/rest_arch_style.htm

Type 'what is RESTful service' in google...dahhhh




Demo

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By Eder Rafo Jose Pariona Espiñal

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