REST Introduction (PHP London)

Representational State Transfer

RESTful Principles

A universal syntax for resource-identification

A set of well-defined operations

Having a shared set of media-types

The use of hypermedia for application state-transitions

Statelessprotocol

Building a RESTful App

RESTfully Delicious

● Get a list of all bookmarks● filter by user and/or tag● limit by number

● Add a bookmark● Edit a bookmark● Delete a bookmark

Discover Resources

Resources URLs Methods RepresentationsBookmark /bookmarks/{md5} GET

PUTDELETE

Bookmark list /bookmarks GETPOST

Users bookmarks /users/{user} GETTagged bookmarks /tags/{tag} GET

application/bookmark+xmlapplication/bookmark+xml

application/atom+xmlapplication/bookmark+xmlapplication/atom+xmlapplication/atom+xml

Resources URLs Methods RepresentationsUser list /users GETTag list /tags GETHomepage / GET

application/atom+xmlapplication/atom+xmlapplication/delicious+xml

GETting the Homepage

GET /

200 OK

Contenttype: application/delicious+xml

<?xml version=”1.0”?>

<delicious users=”/users” bookmarks=”/bookmarks” tags=”/tags”>

<recent start=”1” end=”20” next=”/?start=21&end=40”>

<bookmark url="http://www.example.org/somethingintersting" href="/bookmarks/a211528fb5108cddaa4b0d3aeccdbdcf"/>

...

</recent>

</delicious>

GETting Bookmarks

GET /bookmarks

200 OK

Contenttype: application/atom+xml

<?xml version="1.0"?>

<feed xmlns="http://www.w3.org/2005/Atom">

<title>Bookmarks</title>

<entry>

<title>Something interesting</title>

<link href="/bookmarks/a211528fb5108cddaa4b0d3aeccdbdcf"/>

<summary>http://example.org/somethingintersting</summary>

</entry>

</feed>

GETting A Bookmark

GET /bookmarks/a211528fb5108cddaa4b0d3aeccdbdcf

200 OK

Contenttype: application/bookmark+xml


<bookmark>


<url>http://example.org/somethingintersting</url>

<user href=”/users/pauljames”>pauljames</user>

<tags>

<tag href=”/tags/interesting”>interesting</tag>

</tags>

</bookmark>

Creating and Updating

POST /bookmarks


...

201 Created

Location: /bookmarks/a211528fb5108cddaa4b0d3aeccdbdcf

PUT /bookmarks/a211528fb5108cddaa4b0d3aeccdbdcf


...

200 OK

Benefits of Being RESTful

● Better scaling due to stateless communications ● Better response times due to caching● Better longterm compatibility due to:

● the capability of document types to evolve without breaking backwardscompatibility

● the ability to add support for new content types without reducing support for older content types.

● Do less with more

Finally, some PHP

HTTP method$_SERVER['REQUEST_METHOD']

Reading request data$_SERVER['CONTENT_LENGTH']

$_SERVER['CONTENT_TYPE']

POST - $HTTP_RAW_POST_DATA

Other HTTP methods - fopen('php://input', 'r')

Processing request dataSimpleXML, MiniXML, PHP JSON, parse_str, unserialize,

unpack, preg_match, etc.

Generating ResponsesHTTP response codes

200 OK, 201 Created, 204 No Content, 304 Not Modified, 401 Unauthorized, 404 Not Found, 405 Method Not Allowed, 411 Length Required, 415 Unsupported Media Type

Generating representationsSmarty, PHPFastTemplate, GD, SimpleXML, printf, etc.

HTTP cachingExpires, Cache-Control, Etag, Last-Modifiedheader('Expires: '.gmdate('D, j M Y H:i:s T', time() + $cachelength));

header('CacheControl: maxage='.$cachelength.', mustrevalidate');

Conclusion

● REST is not just about “Web Services”● Set of best practices for building Web apps

● Give everything a URL● Use correct HTTP methods● Use common media types● Link things together with hypertext

Further Reading

● Roger L. Costello (http://www.xfront.com/RESTWebServices.html)

● Paul Prescod (http://www.prescod.net/rest/)● REST Wiki (http://rest.blueoxen.net/)● Atom Publishing Protocol

(http://atomenabled.org/developers/protocol/)● http://del.icio.us/tag/rest

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IntroductionQuestions

Overloaded term

POX over HTTP?Other HTTP methods?Tidy URLs?Buzzword?

http://flickr.com/photos/estherase/128983854/

2

Representational State Transfer

Architectural styleDistilled from the Web by Roy FieldingHTTP 1.1 was designed to conform to RESTDefines how the Web worksDescribes a set of rules for building applications on the

Web that exhibit certain desirable propertiesREST is not HTTP, but HTTP is RESTful

“it’s the way the Web already works, just formalized a bit and with some do’s and don’ts.”

Web service is a Web page that’s meant to be consumed by an autonomous program as opposed to a Web browser

http://flickr.com/photos/practicalowl/392894653/

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RESTful Principles

5 principles

● A universal syntax for resourceidentification URLs● A set of welldefined operations● Having a shared set of mediatypes● The use of hypermedia for application statetransitions● Stateless protocol – all state on the client

http://flickr.com/photos/thowi/113223967/

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● Uniform resource locators (URLs)● Every resource (thing of interest) has a URL● URLs are unique and allow us to dereference a

resource● Nouns● Trillions of nouns for all the concepts in all the heads

and files of all the people in the world

http://flickr.com/photos/joeholmes/258136938/

5

A set of well-defined operations

● HTTP methods verbs● GET – fetch● POST append/process● PUT create/update● DELETE delete● Uniform interface, GET always gets, PUT always

creates● Using different verbs for different nouns would make

widespread communication impossible● There are no applications you can think of which

cannot be made to fit

http://flickr.com/photos/joygant/971783023/

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Having a shared set of media-types

● What's not machineprocessable about the current Web isn't the protocol, it's the content

● Information conveyed via documents● A standard set of document formats (HTML, RDF,

JPEG, PNG, etc.)● Representation of a resource● Resources are just concepts, representations are how

we interact with them

http://flickr.com/photos/thefrankfurtschool/1305454450/

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The use of hypermedia for application state-transitions

● Hypertext provides links between resources● Clients change state (navigate the Web) via information

from a previous state● URLs are opaque to clients, they never construct URLs● Because the links mirror the structure of how a user

makes progress through an application● A Webbased application is a dynamically changing

graph of state representations (pages) and potential transitions (links) between states

● If not, it may be accessible from the Web, but it’s not really part of the Web

http://flickr.com/photos/pgoyette/100769956/

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Statelessprotocol

● Application state is the information necessary to understand the context of an interaction – auth details, etc.

● Resource state – S in REST, avoid unnamed state● All requests must include all application state● Session state is application state – if you want a

session you need a smarter client than a browser – shopping cart

● Prevents partial failures● Loadbalancing● Service interruptions

http://flickr.com/photos/davenyc/23033147/

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Building a RESTful App

● Discover first class objects● Our resources● Assign URLs and URLspaces● Define representations● Input and output formats● Define HTTP methods

Time for an Example

http://flickr.com/photos/hugovk/2037935886/

10

RESTfully Delicious

● Get a list of all bookmarks● filter by user and/or tag● limit by number

● Add a bookmark● Edit a bookmark● Delete a bookmark

Get a list of all bookmarksfilter by user and/or taglimit by number

Add a bookmarkEdit a bookmarkDelete a bookmark

http://flickr.com/photos/sharynmorrow/124428600/

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Discover Resources

Resources URLs Methods RepresentationsBookmark /bookmarks/{md5} GET

PUTDELETE

Bookmark list /bookmarks GETPOST

Users bookmarks /users/{user} GETTagged bookmarks /tags/{tag} GET

application/bookmark+xmlapplication/bookmark+xml

application/atom+xmlapplication/bookmark+xmlapplication/atom+xmlapplication/atom+xml

Resources URLs Methods RepresentationsUser list /users GETTag list /tags GETHomepage / GET

application/atom+xmlapplication/atom+xmlapplication/delicious+xml


12

GETting the Homepage

GET /

200 OK

Contenttype: application/delicious+xml

<?xml version=”1.0”?>

<delicious users=”/users” bookmarks=”/bookmarks” tags=”/tags”>

<recent start=”1” end=”20” next=”/?start=21&end=40”>

<bookmark url="http://www.example.org/somethingintersting" href="/bookmarks/a211528fb5108cddaa4b0d3aeccdbdcf"/>

...

</recent>

</delicious>


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GETting Bookmarks

GET /bookmarks

200 OK

Contenttype: application/atom+xml


<feed xmlns="http://www.w3.org/2005/Atom">

<title>Bookmarks</title>

<entry>


<link href="/bookmarks/a211528fb5108cddaa4b0d3aeccdbdcf"/>

<summary>http://example.org/somethingintersting</summary>

</entry>

</feed>


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GETting A Bookmark

GET /bookmarks/a211528fb5108cddaa4b0d3aeccdbdcf

200 OK



<bookmark>


<url>http://example.org/somethingintersting</url>

<user href=”/users/pauljames”>pauljames</user>

<tags>

<tag href=”/tags/interesting”>interesting</tag>

</tags>

</bookmark>


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Creating and Updating

POST /bookmarks


...

201 Created

Location: /bookmarks/a211528fb5108cddaa4b0d3aeccdbdcf

PUT /bookmarks/a211528fb5108cddaa4b0d3aeccdbdcf


...

200 OK


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Benefits of Being RESTful

● Better scaling due to stateless communications ● Better response times due to caching● Better longterm compatibility due to:

● the capability of document types to evolve without breaking backwardscompatibility

● the ability to add support for new content types without reducing support for older content types.

● Do less with more

Better scaling due to stateless communications Better response times due to cachingBetter longterm compatibility due to:

the capability of document types to evolve without breaking backwardscompatibility

the ability to add support for new content types without reducing support for older content types.

Lower learning curve for consumerLower support overhead for producer

http://flickr.com/photos/ari/1387533615/

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Finally, some PHP

HTTP method$_SERVER['REQUEST_METHOD']

Reading request data$_SERVER['CONTENT_LENGTH']

$_SERVER['CONTENT_TYPE']

POST - $HTTP_RAW_POST_DATA

Other HTTP methods - fopen('php://input', 'r')

Processing request dataSimpleXML, MiniXML, PHP JSON, parse_str, unserialize,

unpack, preg_match, etc.

http://flickr.com/photos/nez/378348754/

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Generating ResponsesHTTP response codes

200 OK, 201 Created, 204 No Content, 304 Not Modified, 401 Unauthorized, 404 Not Found, 405 Method Not Allowed, 411 Length Required, 415 Unsupported Media Type

Generating representationsSmarty, PHPFastTemplate, GD, SimpleXML, printf, etc.

HTTP cachingExpires, Cache-Control, Etag, Last-Modifiedheader('Expires: '.gmdate('D, j M Y H:i:s T', time() + $cachelength));

header('CacheControl: maxage='.$cachelength.', mustrevalidate');

http://flickr.com/photos/nez/378348754/

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Conclusion

● REST is not just about “Web Services”● Set of best practices for building Web apps

● Give everything a URL● Use correct HTTP methods● Use common media types● Link things together with hypertext

REST is not just about “Web Services”Set of best practices for building Web apps

Give everything a URLUse correct HTTP methodsUse common media typesLink things together with hypertext

REST is an architectural styleIt defines 4 core principles


A set of well-defined operationsHaving a shared set of media-typesThe use of hypermedia for application

state-transitionsStateless client/server interaction

It helps us write well behaved appsIt's not just about Web APIs but the

whole Web, “there are no Web Services”

http://flickr.com/photos/naked_dave1/469220787/

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Further Reading

● Roger L. Costello (http://www.xfront.com/RESTWebServices.html)

● Paul Prescod (http://www.prescod.net/rest/)● REST Wiki (http://rest.blueoxen.net/)● Atom Publishing Protocol

(http://atomenabled.org/developers/protocol/)● http://del.icio.us/tag/rest

http://flickr.com/photos/dhammza/91435718/

REST Introduction (PHP London)

Technology

Transcript of REST Introduction (PHP London)