Rest and the hypermedia constraint

REST and HATEOASBen Longden, PHPNW 2011

REST and theHypermedia ConstraintBen Longden, PHPNW 2011

Who are you?

Who are you? @blongden

Who are you?

Who are you? @ibuildings

Who are you?

Who are you? @fdrop

RESTREpresentational State Transfer

REST Series of constraints for distributedhypermedia systems - Roy Fielding, 2000

Constraints are good

Constraints are goodThey (help) stop you from doing crazy things

REST is an Architecture It is not a protocol

GoalsScalabilityGenerality of InterfacesIndependent deployment of componentsIntermediaries to reduce latency,enforce security, and encapsulatelegacy systems.

Client server

Stateless

Layered system

Code on demand

Uniform interface

Uniform interface Identification of resources

Uniform interfaceManipulations of resources through representations

Uniform interface Self descriptive messages

Uniform interfaceHypertext as the engine of application state

The hypermedia constraint?

The hypermedia constraintA URI request returns all valid state changes

The hypermedia constraint It’s how the web works

The hypermedia constraintYou already understand it!

HTTPYour browser speaks the language of text/html

<!DOCTYPE html>

HTMLUsing hypermedia on the web, you can link to different types of data

HTMLUsing hypermedia on the web, you can link to different types of data text/css image/png audio/mpeg

Hypermedia Types “Hypermedia Types are MIME media types that contain native hyper-linkingsemantics that induce application flow.” - Mike Amundsen (2010)

The hypermedia constraintThe client tells the server what language it speaks

The hypermedia constraintThe server tells the client what to do

HTTP/1.1

HTTP/1.1HEAD GET POST PUT DELETE TRACE OPTIONS CONNECT PATCH

GET and POST is OK

GET and POST is OKREST doesn’t care what methods you use

GET and POST is OKHTTP cares that the methods are used correctly

Life in XHTMLThe website is also the API

Life in XHTMLInconvenient and difficult to maintain

False start #1Attempt a custom hypermedia type

False start #2 application/atom+xml

False start #3 application/xhtml+xml

Custom hypermedia types Consider registered types first

Custom hypermedia types More likely to be understood

A solutionapplication/vnd.fdrop.xhtml+xml

A solutionXHTML has hypermedia controls built in

A solutionContains most of what I need

XML based media types Namespaces

Let’s see it then! @RESTConsole

What about JSON?application/vnd.collection+json application/hal+json

Versioning http://www.w3.org/History/19921103-hypertext/hypertext/WWW/TheProject.html

VersioningThe server makes no assumptions on the capabilities of the client

Versioning If the client does not supportsomething, it simply ignores it

VersioningThe web is not versioned

VersioningCorrect use of hypermedia means you canchange things without affecting clients

VersioningBut if you must...

VersioningAccept: application/vnd.fdrop.v2.xhtml+xml

http://tools.ietf.org/html/rfc2616http://tools.ietf.org/html/rfc4287http://amundsen.com/hypermedia/http://amundsen.com/media-types/collection/http://www.flickr.com/photos/bjornmeansbear/4727475559/

http://joind.in/talk/view/3589 @blongden

Rest and the hypermedia constraint

by blongden on Oct 08, 2011

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