REST in peace @ Osidays 2011 India 11-21-2011

RESTin peace

Bengaluru, 20-22 November 2011

Sorry for the ugly slide.

There will be others.Really sorry.



REST in a nutshell

2000Fielding's dissertation:

REpresentational

State

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


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

REST in a nutshell:

1. Client <> ServerBengaluru, 20-22 November 2011

REST in a nutshell:

2. Stateless


Servers do not keep anyinformations the clients uses

during different requests.


So the architecture scales well.


3. Cacheable

REST in a nutshell:


Client has access to resources stored betweenit and the origin server.


So communication is faster.


REST in a nutshell:

4. Layered systemBengaluru, 20-22 November 2011

Intermediary nodes can beused along our architecture.


So you efficiently implement point 3.


REST in a nutshell:

5. Uniform interface


Communicate using well-knownverbs and providing all the

informations needed toconsume a service.


So fallbacks are easy.


this was a bit difficult to understand

so, obviously...


nobody had a clue


ANTIPATTERNS


1URIs


"REST is about

cool URI design"

http://apple.com/users/1/licenses/4.json


"REST is about

cool URI design"

http://apple.com/users/1/licenses/4.json


http://apple.com/site/en_US/showUsers.jsp?uid=1&license=4

is OK too


but, enter simple rule of thumb


cool URIs help youthink in term of resources

- David Zuelke


2URIs (bis)


GET /users POST /users PUT /users/{id} DELETE /users/{id} ...

REST follows a URI schema


GET /users POST /users PUT /users/{id} DELETE /users/{id} ...

REST follows a URI schema


what if you change yourURL?


client is broken


RESTful clients shouldbe driven by service'shypermedia controls

Roy Fielding : http://roy.gbiv.com/untangled/2008/rest-apis-must-be-hypertext-driven


HATEOAS


3POST is cool


said SOAP 1.1


said SOAP 1.1


loosing meaningful verbs at the protocol level



nothing cacheable by default



nothing cacheable by default

what about bookmarking?


4500 is your friend


said SOAP( again )


GET /users/300Host: www.example.com


HTTP/1.1 500 Internal Server ErrorEtag: 1234X-Powered-By: php/5.3...

The record cannot be found



HTTP/1.1 500 Internal Server ErrorEtag: 1234X-Powered-By: php/5.3...

The record cannot be found



The HTTP protocol is awesome,and lets you return meaningful anduniversally-understood status codes


404 Not Found


404 Not Found

OMG Link is broken?


202 Accepted


202 Accepted

You get an immediate OK, and the operation will hopefully complete


Pause


The WWW


the largest data-exchange network on the planet


And meanwhile, at Facebook...

12TB of new data every day(1 year ago)

500 million users


And meanwhile, at Google...

1 billion unique monthly googlers


via HTTP, baby!


HTTP in a nutshell:

1. Client <> ServerBengaluru, 20-22 November 2011

HTTP in a nutshell:

2. Stateless


http://www.w3.org/Protocols/rfc2616/rfc2616-sec13.html

3. widespread cache spec

HTTP in a nutshell:


HTTP in a nutshell:

4. Layered systemOrigin server

Reverse proxy

Great chinese (fire)wall

Company proxy

Lao Tze Song using Firefox 6


HTTP in a nutshell:

5. it is the uniform interfacebetween clients and servers


HTTP bleeds REST


How do Iimplement

thisgoodness?


1. caching & scalability


HTTP cache


Local

Shared/proxy

Shared/reverse proxy

Types of cache


Local

Shared/proxy


Types of cache



Local

Shared/proxy


Types of cache



Local

Shared/proxy


Types of cache



on the server side


Caching withExpiration(example)


HTTP/1.1 200 OKHost: www.example.comExpires: 0


HTTP/1.1 200 OKHost: www.example.comExpires: 0


HTTP/1.1 200 OKHost: www.example.comExpires: Tue, 31 Jan 2011 01:00 GMT


HTTP/1.1 200 OKHost: www.example.comCache-Control: max-age=60, public





Cacheable for 60 seconds



Cacheable by both local and shared caches


You can also cache with validation

(Etags, If-None-Match, ...)


Why HTTP cachingis so

important?


Ask yourself:as a developer, what do I want

on my application?


Evolve

Loose coupling

Work less


Evolve Because you want your platform to extensible

Loose coupling

Work less



Loose coupling Because you want it to be easy to integrate with, evolve, plug and mantain

Work less



Loose coupling Because you want it to be easy to integrate with, evolve, plug and mantain

Work less

Because every LoC is bug-prone and our man-day is a hard-to-scale cost


enters our Hero #1




enters our Hero #2



http://www.lullabot.com/articles/a-beginners-guide-to-caching-data


http://www.lullabot.com/articles/a-beginners-guide-to-caching-data

2007


2011?


it supportsHTTP caching!

http://drupal.org/node/147310



it supportsHTTP caching!


( people is supposed to clap their hands here )



but


wait.... how?


Default headers

Expires = 'Sun, 19 Nov 1978 05:00:00 GMT',

Cache-Control = 'no-cache, must-revalidate',

ETag = $_SERVER['REQUEST_TIME'],


Default headers





Default headers





Default headers





is that even legal?


"but you can redefine them!"


drupal_add_http_header()


function drupal_add_http_header(){ ...

...

drupal_send_headers($headers);}


so, what

drupal_send_headers()

can do so evil?


header(),

of course


which means


drupal_add_http_header('Dumb-Header', 'I\'m batman!');...// other logic...drupal_add_http_header('Dumb-Header', 'I\'m not');

var_dump(headers_list());


drupal_add_http_header('Dumb-Header', 'I\'m batman!');...// other logic...drupal_add_http_header('Dumb-Header', 'I\'m not');


array 0 => string 'X-Powered-By: PHP/5.3.2-1ubuntu4.7' 1 => string 'Dump-Header: I'm not'


drupal_add_http_header('Dumb-Header', 'I\'m batman!');...// other logic...drupal_add_http_header('Dumb-Header', false);



drupal_add_http_header('Dumb-Header', 'I\'m batman!');...// other logic...drupal_add_http_header('Dumb-Header', false);


array 0 => string 'X-Powered-By: PHP/5.3.2-1ubuntu4.7' 1 => string 'Dump-Header: I'm batman'


drupal_add_http_header('Dumb-Header', 'I\'m batman!');...// other logic...drupal_add_http_header('Dumb-Header', ' ');



drupal_add_http_header('Dumb-Header', 'I\'m batman!');...// other logic...drupal_add_http_header('Dumb-Header', ' ');


array 0 => string 'X-Powered-By: PHP/5.3.2-1ubuntu4.7' 1 => string 'Dumb-Header:'


or


you can use header_remove()

( PHP 5.3 )


and create a new class to manage/keep track of

headers and caching directives


but we're lazy

and

we don't want to reinvent the wheel


Goals

Work lessevolve

loose coupling


Goals

Work lessevolve

loose coupling


everything is done for us!

:)

but....


tmp files, cache tables, procedural code...

mmmmh....

gotta be something better


Frameworks



ONE


Cache is used for compiling routes, autoloading, ...


Cache is used for compiling routes, autoloading, ...

...but also for storing the view


Goals

Work lessevolve

loose coupling


Goals

Work lessevolve

loose coupling


at least because we use a framework


HTTP

Less work


because the hard work is delegated to the browser/proxy

http://www.flickr.com/photos/snakphotography/5004775320/sizes/o/in/photostream/


Evolve


because cache is abstracted from the application


Loose coupling


because caching is bound to the protocol, HTTP, not to your implementation ( Sf, RoR, Django )


but hey, you say


HTTP's cache fails when dealing with really dynamic pages, because consumers will always have to hit the

origin server, although a part of the page would be cacheable ( header and footer, for example )


Nope

Nope


ESI was built for thathttp://www.w3.org/TR/esi-lang


Edge Side IncludesA de facto standard for bla bla bla...


Edge Side IncludesA de facto standard for bla bla bla...

Server side includes ( not SSI! ) usually handled by the architecture's ESI processor.

http://www.w3.org/TR/esi-langhttp://www.w3.org/TR/edge-arch

http://www.w3.org/TR/esi-lang

http://www.w3.org/TR/edge-arch

<esi:include src="http://osidays.com/talks/1" />






1s (tweets)

3600 (post)


<esi:include src='tweets.html' />

<esi:include src='article/12.html' />


2. adaptability & durability


Hypermediaanother long-time friend


Linksoutrageously semplifying


<img src="..." />

<a href="..." />

<link rel="payment" ... />


<img src="..." />

<a href="..." />



<img src="..." />

<a href="..." />



<link rel="payment" href="/checkout" type="text/html" ... />








HTTP/1.1 201 CreatedHost: www.example.comEtag: 1234X-Powered-By: php/5.3Location: /users/1

POST /usersHost: www.example.com


HTTP/1.1 201 CreatedHost: www.example.comEtag: 1234X-Powered-By: php/5.3Location: /users/1



HTTP/1.1 201 CreatedHost: www.example.comEtag: 1234X-Powered-By: php/5.3Location: /new-users-db/1



HTTP/1.1 201 CreatedHost: www.example.comEtag: 1234X-Powered-By: php/5.3Location: /new-users-db/1



consumers of your API are able to followthe changes of your design


Client knows how to consume the service based on the informationsauto-provided by the service itself


No WSDL.


No URI templates.


No easily-outdated documentation.


No assumptions.


Less WTFs.



This does not easily break.


HATEOASHypermedia As The Engine Of Application State



6

everything seems eventually

cool

Recap: why REST?Bengaluru, 20-22 November 2011

Pros

PerformancesBengaluru, 20-22 November 2011

Pros

Scalability


Pros

Durability


Not RESTful?


Simply don't care


Rules of architectural design


Follow them accordingto your needs


amazon.com


So...



Alessandro Nadalin


odino.org


a


a


@_odino_ #osidays

a


@_odino_

Thank YOU!

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Technology

REST in peace @ Osidays 2011 India 11-21-2011