RESTful Web Services

RESTful Web Services

Presented by Greg Hines

What Are Web Services?

“The Machine-Readable Web”

Two Styles of Web Service

Service-Oriented ArchitectureSOAP, XML-RPC, etc.

Resource-Oriented Architecture

REST

“The Human-Readable Web”

URLs + HTTP + HTML

URI + HTTP + HTML

URI + HTTP + Links

URI + HTTP + Hypermedia

Fundamental Web Technologies

REST means using fundamental web technologies idiomatically as the basis for

designing web services.

Why use REST?

The Web Was Designed For It

The Web Was Designed For It(Sort of.)

Appeal to AuthorityAn appeal to authority or argument by authority is a type of argument in logic consisting on basing the truth value of an assertion on the authority, knowledge, expertise, or position of the person asserting it.

–Wikipedia

Roy T. Fielding, Ph.D.

• Co-founder, chairman of the Apache Software Foundation

• Co-founder of the Apache HTTP Project• On IETF working groups for HTTP, URI, and HTML• Architectural principal on HTTP working group • First name on HTTP spec

• Originator of REST

Sam Ruby

• Board member of the Apache Software Foundation• Co-chair of W3C’s HTML Working Group• Co-creator of the Web Feed Validator• Originator of Atom• Secretary of the IETF’s AtomPub working group• Co-author of “RESTful Web Services”

Greg Hines

• Currently giving a presentation about REST

Fielding developed REST while writing HTTP 1.1…

Fielding developed REST while writing HTTP 1.1…

What have you done lately?

Aspects of a RESTfulWeb Service

Resources

Resources

A resource can be practically anything.

• A blog post• A collection of blog posts• An image• A user• Map coordinates• A bank transaction• Search results

Representations

A Kitten

Some Text

Name: BobBreed: TabbyFur Length: MediumFur Color: Gray, Brown, WhiteAge: 8 monthsPersonality: Outgoing, but loves to cuddle.

A Picture

A Drawing

A Haiku

My cat is named Bob.I named him after Bob. Bob’s breath smells like cat food.

A Blog Post

HTML<!DOCTYPE html><html lang="en"> <head> <title>Greg's Blog: My First Blog Post</title> </head> <body> <article> <header> <h1>My First Blog Post</h1> <p>By Greg Hines</p> </header> <p>This is my first blog post. Woo.</p> <footer> <p>Posted on February 2, 2012 at 12:18 PM</p> <ul class="tags"> <li><a href="/tags/awesome">awesome</a></li> </ul> <p><a href="/entries/2012/02/my-first-blog-post">permalink</a></p> </footer> </article> </body></html>

JSON

{ "uri": "/entries/2012/02/my-first-blog-post", "title": "My First Blog Post", "author": "/users/greg", "created": 1328728680, "content": "This is my first blog post. Woo.", "tags": [ "/tags/awesome" ]}

Addressability

AddressabilityEvery resource has at least one URI;

every URI points to a resource.

http://example.com/entries/2012/02/restful-web-services

http://example.com/tags/awesome

http://example.com/

Interface Uniformity


GET POST


GET POST

PUT DELETE


GET POST PUT

DELETE HEAD OPTIONS


GET POST PUT

DELETE HEAD OPTIONS

TRACE CONNECT


GET POST PUT

DELETE HEAD OPTIONS


GET POST PUT

DELETE HEAD OPTIONS

PATCH

Idempotency

Being able to perform an operationmultiple times without changing the result

after the initial operation.


GET POST PUT

DELETE HEAD OPTIONS

Status Codes

Connectedness

Resources Link to Each Other

Connectedness

<?xml version="1.0" encoding="UTF-8"?><resource xmlns="http://example.com/ns/resource"> <content>...</content> <nextResource href="http://example.com/resource/3"/>

<prevResource href="http://example.com/resource/1"/>

</resource>

Connectedness

<?xml version="1.0" encoding="UTF-8"?><resource xmlns="http://example.com/ns/resource"> <content>...</content> <nextResource href="http://example.com/resource/3"/>

<prevResource href="http://example.com/resource/1"/>

</resource>

<link rel="alternate" type="application/atom+xml" href="http://example.com/resource/2.atom" />

HATEOAS

Statelessness

HTTP Is Stateless

Every RequestHappens in Isolation

State Machine

Resource StateServer-Side

Application StateClient-Side

Transferring State

Every HTTP request transfers state between the application and the requested resource.

Resource Applicatione.g. GET

Resource Applicatione.g. PUT

Representation State Transfer

Representation State TransferI see what you did there…

Richardson Maturity Model

Plain Old XMLLevel Zero

ResourcesLevel One

HTTP VerbsLevel Two

HypermediaLevel Three

Strive for Level Three

Be OK with Level Two

Be Embarrassed by Level One

Die in a Fire for Level Zero

RESTful Web Services

Technology

Transcript of RESTful Web Services