rest in ( a mobile ) peace @ whymca 05-21-2011
DESCRIPTION
RESTful architectures and the advantage for HTTP consumers.Focused on what matters to the mobile world: performances & scalability.TRANSCRIPT
RESTin (a mobile) peace
Alessandro Nadalin
May, 21st 2011
AgendaRest in a nutshellREST antipatternREST for the mobile world
HowHTTP cache fault-tolerance, downtime-availabilityESI Atom + Hypermedia controls
Whyperformancesevolution costadaptability
Sorry for the ugly slide.
There will be others.Really sorry.
A nutshellin (a mobile) peace
Let's go back!
http://www.ics.uci.edu/~fielding/pubs/dissertation/rest_arch_style.htm
2000Fielding's dissertation:
REpresentational
State
Transfer
REST in a nutshell:
REST in a nutshell:
1. Client <> Server
REST in a nutshell:
2. Stateless
easy toscale
Recover andfailoverparadise
What about the user session?
Must die
3. Cacheable
REST in a nutshell:
When dealing with safe methods,the response should be able to tell the client,
or whatever stands behind the request,how to cache it.
REST in a nutshell:
REST in a nutshell:
4. Layered system
REST in a nutshell:
5. Uniform interface
Uniform interfacehierarchic resource identification
Verbs to perform operations
manipulation through representation
HATEOAS
Richardson maturity model
hierarchic resource identification
Verbs to perform operations
manipulation through representation
HATEOAS
Really well explained by Fowler: http://martinfowler.com/articles/richardsonMaturityModel.html#level0
Richardson maturity model
hierarchic resource identification
Verbs to perform operations
HATEOAS
mess
Richardson maturity model
hierarchic resource identification
Verbs to perform operations
HATEOAS
mess0.
0Using HTTP
Without giving a f***
Richardson maturity model
hierarchic resource identification
Verbs to perform operations
HATEOAS
mess0.1.
1mytastyproduct.com/users
mytastyproduct.com/users/1/licenses/4
Richardson maturity model
hierarchic resource identification
Verbs to perform operations
HATEOAS
mess0.1.2.
2
3.
Richardson maturity model
hierarchic resource identification
Verbs to perform operations
HATEOAS
mess0.1.2.
3. GOD
http://www.slideshare.net/trilancer/why-hateoas-1547275
Hyperlinks
Single entry point
Uniform interface is interesting.
Everyone seem to have its own RESTful "service".
But no one seem to entirely implement a uniform interface.
Uniform interface is interesting.
Everyone seem to have its own RESTful "service".
But no one seem to entirely implement a uniform interface.
That means... ...?
No RESTful
stuff
But don't be too religious.
REST gets raped everyday, get over it.
( a few ) ANTIPATTERNSin (a mobile) peace
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
"cool URIs help youthink in term of resources"
- David Zuelke
and, by the way
a URI should neverlocate different resources
a URI should neverlocate different resources
while a resource could belocated by different URIs
2URIs (bis)
REST follows a URI schema
REST follows a URI schema
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} ...
URI templates suck, some say
what if you change yourURL?
Yeah, 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
3Formats
REST
=
XML
REST
=
XML
a representation variesbased on the format
Can be:application/xmlapplication/jsonaudio/mp4image/png
Can be:application/xmlapplication/jsonaudio/mp4image/png
but also:text/dnsvideo/vnd.motorola.videotext/uri-list
dear JSON, by the way
JSON is evil
{ "date": "2011-01-01", "stock": "100", "price": "12"}
The business evolves
{ "date": "2011-01-01", "stock": "100", "price": [ {"currency": "EUR", "amount": "12"}, {"currency": "USD", "amount": "10"} ]}
Credits: http://twitter.com/#!/odracci
Yeah, client is broken
Everything is a tradeoff
4POST is cool
said SOAP 1.1
said SOAP 1.1
loosing meaningful verbs at the protocol level
loosing meaningful verbs at the protocol level
nothing cacheable by default
loosing meaningful verbs at the protocol level
nothing cacheable by default
what about bookmarking?
5500 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
GET /users/300Host: www.example.com
HTTP/1.1 500 Internal Server ErrorEtag: 1234X-Powered-By: php/5.3...
The record cannot be found
GET /users/300Host: www.example.com
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
412 Precondition Failed
412 Precondition Failed
Want money?.. Got money?
The serious s**tin (a mobile) peace
How do Iimplement
thisgoodness?
1.
caching & scalability
HTTPyour long-time friend
Local
Shared/proxy
Shared/reverse proxy
Types of cache
Local
Shared/proxy
Shared/reverse proxy
Types of cache
Local
Shared/proxy
Shared/reverse proxy
Types of cache
Local
Shared/proxy
Shared/reverse proxy
Types of cache
on the server side
Proxy Reverse proxy
http://www.codeproject.com/KB/aspnet/ExploringCaching.aspx
There is something cool about caching softwares.
Free as free beer
...but the server should take advantage of them
( the boring part were you need to write code )
and here are a few ways to do so, using
and here are a few ways to do so, using
expiration
and here are a few ways to do so, using
expiration
validation
and here are a few ways to do so, using
expiration
validation
invalidation
and here are a few ways to do so, using
expiration
validation
invalidationwe will se why
Expiration
GET / HTTP/1.1Host: www.example.comExpires: 0
GET / HTTP/1.1Host: www.example.comExpires: 0
GET / HTTP/1.1Host: www.example.comExpires: Tue, 15 Nov 1994 01:00 GMT
GET / HTTP/1.1Host: www.example.comCache-Control: max-age=60, public
GET / HTTP/1.1Host: www.example.comCache-Control: max-age=60, public
GET / HTTP/1.1Host: www.example.comCache-Control: max-age=60, public
Cacheable for 60 seconds
GET / HTTP/1.1Host: www.example.comCache-Control: max-age=60, public
Cacheable by both local and shared caches
GET / HTTP/1.1Host: www.example.comCache-Control: stale-if-error=600, stale-while-revalidate=600
GET / HTTP/1.1Host: www.example.comCache-Control: stale-if-error=600, stale-while-revalidate=600
fault-tolerant
GET / HTTP/1.1Host: www.example.comCache-Control: stale-if-error=600, stale-while-revalidate=600
available during downtime
GET / HTTP/1.1Host: www.example.comCache-Control: stale-if-error=600, stale-while-revalidate=600
available during revalidation
Validation
GET / HTTP/1.1Host: www.example.comEtag: 1234
GET / HTTP/1.1Host: www.example.comEtag: 1234
an identifier for your response
GET / HTTP/1.1Host: www.example.comIf-None-Match: 1234
the browsers asks you if it has been modified
Conditional requests
Relax
Calculating an Etag is cheaper than generating a full MVC response
HTTP/1.1 304 Not Modified
GET / HTTP/1.1Host: www.example.comLast-Modified: Tue, 15 Jan 2011 12:00:00 GMT
GET / HTTP/1.1Host: www.example.comLast-Modified: Tue, 15 Jan 2011 12:00:00 GMT
tell the client about the latest change
GET / HTTP/1.1Host: www.example.comIf-Modified-Since: Tue, 15 Jan 2011 12:00:00 GMT
the client asks you if it has been modified since the last time
Conditional requests
Relax
Calculating a date is cheaper than retrieving an entire object
HTTP/1.1 304 Not Modified
Invalidation
The web is not meant for invalidating data.
Server should not be able to keep clients' state, otherwise they wont scale well.
That's why long-polling and endless connections haven't had big success dealing with caching.
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
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
<esi:include src="http://whymca.org/talks/1" />
<esi:include src="http://whymca.org/talks/1" />
<esi:include src="http://whymca.org/talks/1" />
This is a response
15 seconds cache
30 minutes cache
and hey, Varnish is a reverse proxy implementing what you need of the ESI specification
take 2, pay for 1
So what does HTTP cache is meant to solve?
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 )
2.
adaptability & durability
Hypermediaanother long-time friend
Linksoutrageously semplifying
<img src="..." />
<a href="..." />
<link rel="payment" ... />
<img src="..." />
<a href="..." />
<link rel="payment" ... />
<img src="..." />
<a href="..." />
<link rel="payment" ... />
<link rel="payment" href="/checkout" type="text/html" ... />
<link rel="payment" href="/checkout" type="text/html" ... />
<link rel="payment" href="/checkout" type="text/html" ... />
<link rel="payment" href="/checkout" type="text/html" ... />
POST /usersHost: www.example.com
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
POST /usersHost: www.example.com
POST /usersHost: www.example.com
HTTP/1.1 301 Moved permanentlyHost: www.example.comLocation: /users
POST /usersHost: www.example.com
POST /usersHost: www.example.com
HTTP/1.1 201 CreatedHost: www.example.comEtag: 1234X-Powered-By: php/5.3Location: /newusersdatabase/1
POST /usersHost: www.example.com
HTTP/1.1 201 CreatedHost: www.example.comEtag: 1234X-Powered-By: php/5.3Location: /newusersdatabase/1
POST /usersHost: www.example.com
HTTP/1.1 201 CreatedHost: www.example.comEtag: 1234X-Powered-By: php/5.3Location: /newusersdatabase/1
POST /usersHost: www.example.com
Helps refactoring legacy stuff indeed :)
consumers of your API are able to followthe changes of your design
Clients are too importantto break'em
and here comes a controversial part...
Like it or not,
XML is a friend of the non BC-breaking evolution
http://www.slideshare.net/Wombert/xml-versus-the-new-kids-on-the-block-phpbnl11-20110129http://www.odino.org/320/long-live-xml-too-sorry-for-json-fanboyz
BTW<xml...> <product...> <price>25</price> </product></xml>
BTW<xml...> <product...> <price currency="EUR">25</price> <price currency="USD">23</price> </product></xml>
As said, everything is a tradeoff
Choose the media typefor your needs
No need to be religious. Ever.
Why beingin (a mobile) peace?
everything seems cool
everything seems cool
but
why REST?
Pros
Performances
Pros
Scalability
http://articles.sfgate.com/2011-02-20/opinion/28613184_1_news-network-cable-and-satellite-website
http://tech.groups.yahoo.com/group/rest-discuss/message/17370
+2.500%traffic
Pros
Durability
"REST is software design on the scale of decades: every detail is intended to promote software longevity and independent evolution. Many of the constraints are directly
opposed to short-term efficiency. Unfortunately, people are fairly good at short-term design, and usually awful at long-term design. "
Roy Fielding
Put a bit of REST
everywhere
Rules of good design
amazon.it
Alessandro Nadalin
Alessandro Nadalinodino.org
Alessandro Nadalinodino.org
@_odino_
Alessandro Nadalinodino.org
@_odino_
Thanks
Alessandro Nadalinodino.org
@_odino_
Creditshttp://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/http://www.flickr.com/photos/13606325@N08/2416993706/sizes/o/in/photostream/
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/