Rest And Ajax Reconciled

REST and AJAX reconciled Lars Trieloff at AJAX World East 2008

What is REST?

What is REST? • Buzzword

What is REST? • Buzzword • Alternative to SOAP

What is REST? • Buzzword • Alternative to SOAP • Representational State Transfer

What is REST? • Buzzword • Alternative to SOAP • Representational State Transfer • Architecture of the World Wide Web

What is REST? • Buzzword • Alternative to SOAP • Representational State Transfer • Architecture of the World Wide Web • Architecture for Scalable Network Applications

How do we start? • Introduction • Core Concepts • REST Clients • AJAX REST Clients • REST Frameworks • REST Frameworks for AJAX

Things are Resources Resource

Resources can be items of information (a blog entry) or or informational descriptions of real things (a blog author)

Resources have URIs Resource

URI

Uniform Resource Identifier are unique ids for resources, just like ISBN for a book or a driver’s license for a person

Resources have Representations

Representation

Resource

Representation

URI

Representations can have different formats (HTML, XML, JSON) or show different aspects of a resource.

Representations have URLs URL Representation

URL Resource

Representation

URI

Uniform Resource Locators describe how to get to a representation of a resource, they include protocol, hostname, path and extra information

Clients interact via Verbs GET

URL Representation

POST

PUT

Resource

URL Representation

URI

Uniform Resource Locators describe how to get to a representation of a resource, they include protocol, hostname, path and extra information

DELETE

GET is for reading GET

Representation

Representation

Resource

Resource

Before

After

GET is a “safe” method. There are no side-effects, and the requested resource stays unmodified.

PUT is for replacing PUT

Representation

Representation

Resource

Resource

Before

After

PUT is a “idempotent” method. Issuing the same PUT request multiple times yields the same result.

DELETE is for deleting DELETE

Representation

Resource

Before

After

DELETE is also “idempotent”. Deleting a resource twice yields the same result - the resource is gone.

POST is for action POST

Representation

Representation

Representation

Resource

Resource

Resource

Before

After

POST is neither safe nor idempotent. It is used for updating, creating and executing resources.

So what? • There are unlimited resources • Every resource can be addressed • There are only four verbs • Resources have an uniform interface This makes it easy to write clients for existing REST applications and makes it easy to expose a RESTful interface to an application.

How do we go on? • Introduction • Core Concepts • REST Clients • AJAX REST Clients • REST Frameworks • REST Frameworks for AJAX

What are REST Clients • Libwww • Microsoft Internet Explorer • Apache Commons HTTPClient • Mozilla Firefox • Python httplib • Apple Safari • Ruby Net::HTTP • Opera

HTTP Client Libraries

+ Desktop Applications + +Server-side mashups - Not in the web browser Full HTTP Support

Web Browsers as HTTP Clients

+ +Everywhere installed - Weak HTTP Support - Web Forms 1.0 - Browser Bugs No client needed

Web Forms 1.0

d e d o c n e l r u m r o f w w w x / n enctype="applicatio /label> < e l t i T > " e l t i t " = r o f l e b a l t i t " = e m a n " t x e t " = e p y t e b a l / < y r t n E > " t x e t " = r o f

Web Forms 1.0 I o d w But ho change rmlly oa e d e d o c n h e l r u t m r o f w f w w x / o n ) e applicatio " = e p c y t c n r e u o res ? m r o fTitle e"> l t i t " = e m a n " t x e t " = e p y t e b a l / < y r t n E > " t x e t " = r o f

Web Forms 1.0

Why d I o o d a w o n d POS only GE But h change T T w rmlly oa nd i c ype= t c gnore n r e u o s re d ? ? m r o f "title">Title l t i t " = e m a n " t x e t " = e p y t e b a l / < y r t n E > " t x e t " = r o f

Web Forms 1.0

Why d I o o d a w o n d POS only GE But h change T T w rmlly oa nd i c ype= t c gnore n r e u o s re d ? ? m r o f "title">Title l t i t " = e m a n " t x e t " = e p y t e b a l / < y r t n E > " t x e t " = r o f

How do I specify a different encoding, for example XML or JSON?

Solutions: • Changing the action dynamically: URI Templates

• Other Methods than POST and GET: Web Forms 2.0

• More advanced encodings: Web Forms 2.0 http://bitworking.org/projects/URI-Templates/ http://www.whatwg.org/specs/web-forms/current-work/

Solution for now: making browsers better HTTP clients using

AJAX

Where are we now? • Introduction • Core Concepts • REST Clients • AJAX REST Clients • REST Frameworks • REST Frameworks for AJAX

With AJAX we can • get data-only (JSON) representations of web pages in the background

• Overload Web Forms 1.0 behavior, and make them 2.0

• issue data-only (JSON) HTTP requests to these very resources

Getting alternate Representations tle>