Restinpeaceosidays2011 111121093818-phpapp02

RESTin peace
Bengaluru, 20-22 November 2011

Sorry for the ugly slide.

There will be others.
Really sorry.


REST in a nutshell


2000
Fielding's dissertation:

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


REST in a nutshell:

1. Client <> Server

REST in a nutshell:

2. Stateless

Servers do not keep any
informations the clients uses
during different requests.


So the architecture scales well.


REST in a nutshell:

3. Cacheable

Client has access to
resources stored between
it and the origin server.


So communication is faster.


REST in a nutshell:

4. Layered system

Intermediary nodes can be
used along our architecture.


So you efficiently implement
point 3.


REST in a nutshell:

5. Uniform
interface

Communicate using well-known
verbs and providing all the
informations needed to
consume a service.


So fallbacks are easy.


this was a bit difficult to understand

so, obviously...


nobody had a clue


ANTIPATTERNS


1
URIs


"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 you
think in term of resources
- David Zuelke


2
URIs (bis)


REST follows a URI schema

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


what if you change your
URL?


client is
broken

RESTful clients should
be driven by service's
hypermedia controls
Roy Fielding : http://roy.gbiv.com/untangled/2008/rest-apis-must-be-hypertext-driven


HATEOAS

3
POST is cool


said SOAP 1.1


loosing meaningful verbs at the protocol level



nothing cacheable by default



nothing cacheable by default

what about bookmarking?


4
500 is your friend


said SOAP
( again )


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


GET /users/300

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

The record cannot be found


The HTTP protocol is awesome,
and lets you return meaningful and
universally-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 <> Server

HTTP in a nutshell:

2. Stateless

HTTP in a nutshell:

3. widespread cache spec
http://www.w3.org/Protocols/rfc2616/rfc2616-sec13.html


HTTP in a nutshell:
Lao Tze Song using Firefox 6
Company proxy
Great chinese (fire)wall
Reverse proxy
Origin server

4. Layered system

HTTP in a nutshell:

5. it is the uniform interface
between clients and servers

HTTP bleeds REST


How do I
implement
this
goodness?

1.
caching & scalability


HTTP cache


Types of cache

Local

Shared/proxy

Shared/reverse proxy


on the server side


Caching with
Expiration
(example)

HTTP/1.1 200 OK
Expires: 0


HTTP/1.1 200 OK
Expires: Tue, 31 Jan 2011 01:00 GMT


HTTP/1.1 200 OK
Cache-Control: max-age=60, public


HTTP/1.1 200 OK

Cacheable for 60 seconds


HTTP/1.1 200 OK

Cacheable by both local and shared caches


You can also cache with
validation
(Etags, If-None-Match, ...)


Why HTTP caching
is 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


Evolve


Loose coupling

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

Work less


Evolve


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


2007


2011?


it supports
HTTP caching!
http://drupal.org/node/147310


it supports
HTTP caching!
http://drupal.org/node/147310
( 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'],


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());


...
// 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'


...
// other logic
...
drupal_add_http_header('Dumb-Header', false);



...
// other logic
...
drupal_add_http_header('Dumb-Header', false);


array
1 => string 'Dump-Header: I'm batman'


...
// other logic
...
drupal_add_http_header('Dumb-Header', ' ');



...
// other logic
...
drupal_add_http_header('Dumb-Header', ' ');


array
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 less
evolve
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


at least because we use a framework


Less work


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

because the hard work is delegated to the browser/proxy


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


Edge Side Includes
A de facto standard for bla bla bla...


Edge Side Includes
A 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-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


Hypermedia
another long-time friend


Links
outrageously semplifying


POST /users
Host: www.example.
com

HTTP/1.1 201 Created
Etag: 1234
Location: /users/1

POST /users
Host: www.example.
com

HTTP/1.1 201 Created
Etag: 1234
Location: /new-users-db/1

consumers of your API are able to follow
the changes of your design


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


No WSDL.


No URI templates.


No easily-outdated documentation.


No assumptions.


Less WTFs.


This does not easily break.


HATEOAS
Hypermedia As The Engine Of Application State


6


everything
seems eventually
cool

Recap: why REST?

Pros

Performances

Pros

Scalability


Pros
Durability


Not RESTful?


Simply don't care


Rules of architectural design


Follow them according
to your needs


amazon.com


So...


Alessandro Nadalin


odino.org


@_odino_ #osidays


Thank YOU!
@_odino_


Credits
http://www.flickr.com/photos/larachris/16564077/sizes/o/in/photostream/
http://www.flickr.com/photos/ashatenbroeke/4367373081/sizes/z/in/photostream/
http://www.flickr.com/photos/yourdon/3140270189/sizes/l/in/photostream/
http://www.flickr.com/photos/jox1989/4964706072/sizes/l/in/photostream/
http://www.flickr.com/photos/brainfg/168506259/sizes/o/in/photostream/
http://www.flickr.com/photos/norte_it/3897091546/sizes/o/in/photostream/
http://www.zdnet.com/blog/service-oriented/soap-versus-rest-a-matter-of-style/3568
http://www.flickr.com/photos/turtlemom_nancy/2046347762/sizes/l/in/photostream/
http://www.flickr.com/photos/juanpg/3333385784/sizes/z/in/photostream/
http://www.flickr.com/photos/congvo/301678287/sizes/l/in/photostream/
http://www.flickr.com/photos/ihasb33r/2573196546/sizes/z/in/photostream/
http://www.flickr.com/photos/martin_heigan/4544138976/sizes/o/in/photostream/
http://www.flickr.com/photos/cknara/4195099999/sizes/o/in/photostream/
http://www.flickr.com/photos/1080p/3076529265/sizes/l/in/photostream/
http://www.flickr.com/photos/adamrice/280300202/sizes/l/in/photostream/
http://www.flickr.com/photos/tomer_a/541411897/sizes/o/in/photostream/
http://www.flickr.com/photos/subpra/4514008262/sizes/l/in/photostream/
http://www.flickr.com/photos/lippincott/2539720043/sizes/l/in/photostream/
http://www.flickr.com/photos/rawryder/5086090931/sizes/l/in/photostream/
http://www.flickr.com/photos/robboudon/5312731161/sizes/l/in/photostream/
http://www.flickr.com/photos/bc-burnslibrary/4158243488/sizes/o/in/photostream/
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http://www.flickr.com/photos/neothezion/5135841069/sizes/l/in/photostream/
http://www.flickr.com/photos/planetschwa/2494067809/
http://www.flickr.com/photos/thomasthomas/258931782/
http://www.flickr.com/photos/rustyboxcars/2629631562/sizes/l/in/photostream/
http://www.flickr.com/photos/ell-r-brown/4138727474/sizes/l/in/photostream/
http://www.flickr.com/photos/noah123/5082076630/sizes/z/in/photostream/
http://www.flickr.com/photos/jungle_boy/220181177/sizes/l/in/photostream/
http://www.flickr.com/photos/prettydaisies/872539081/sizes/l/in/photostream/
http://www.flickr.com/photos/kaptainkobold/76256150/sizes/o/in/photostream/
http://www.flickr.com/photos/uomoincravatta/1438372865/sizes/z/in/photostream/


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