RESTful web

RESTful Webfrom RESTful style to RESTful code work !!!@PengEdy

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Table of Contents

• Web & Web Service

!• Details of REST Style

!• Some Examples

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Web & Web Service

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Web Service

• Normally: a method of communications over the WWW

!• W3C Definition: a software system

• Designed to support interoperable machine-to-machine interaction

• Over network

• An interface with a certain format: WSDL

• Other systems interact with the Web Service

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The ways we are using web service:

• RPC: Remote Procedure Call

• Strong Coupling

• SOA: Service-oriented Architecture

• This is a good choice.

• REST: Representational State Transfer

• Another choice

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Demo of RPC

• Server

getUser()

addUser()

removeUser()

updateUser()

getLocation()

addLocation()

removeLocation()

updateLocation()

• Client

exampleAppObject = new

ExampleApp(“example.com:1234”)

exampleAppObject.getUser()

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Demo of REST

• Server

http://example.com/users/

http://example.com/users/{user}

http://example.com/findUserForm

http://example.com/locations

http://example.con/locations/{location}

http://example.com/findLocationForm

• Client

userResource = new

Resource(http://example.com/users/001)

userResource.get()

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Our Web…

• Human Web

• For normal users

• Website, Web Application, etc.

• Programmable Web

• For program/programmer

• A set of API

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Web History

• Stage 1: Static Content

• At the beginning of web

• Full of static HTML content, which is the papers made by the scholar

• Like a file sharing server supports Hypertext

!• Is that enough ? We want MORE !

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Web History

• Stage 2: CGI Program

• People wanted to have more function on the web.

• API appeared.

• CGI is made by C/C++, Perl, and some other language, which is powerful but a little tricky.

!• But, we want it better…

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Web History

• Stage 3: Script Languages

• CGI is not safe, so we have script languages.

• ASP, JSP, PHP, Java Applet, JavaScript, etc…

• HTML was mixed with scripts, which is much more safe and powerful.

!• Well, it was still tricky for developers with pure scripts.

• The mixture of HTML and script was horrible when code increased.

!• And, we want more !

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Web History

• Stage 4: Thin Client

• All the content was produced on the server.

• And we had MVC !

• Back-end technology runs fast in this stage.

!• Still, we want more !

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Web History

• Stage 5: Rich Interactive Application (RIA)

• Developers started to build single page application, which can be very useful on the desktop.

• Front-end technology started to run.

• Ajax, jQuery/jQuery UI, ExtJS, Prototype, etc…

• Flex, Sliverlight, JavaFX

• ……

!• Always, we want more !

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Web History

• Stage 6: Mobile Application

• RIA is great, we now have something greater — mobile web.

• iOS, Android, Windows Phone, Blackberry, etc..

• HTML5 + CSS3 + JavaScript

!• We are happy with it now, while we both know that’s not enough.

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Web NOW !

• Pure HTML is not enough.

• CGI and scripts suck.

• Developers, users, administrators want to be happy !

!• So, we have made our mind and technology improved:

• Resource Oriented

• HTTP 1.1: request method, status code, cache

• REST

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RESTful and Resource Oriented Architecture

• REST: Representational State Transfer

• a style, not a standerd

• ROA

• What is resource: anything useful

• Resources must have URIs.

• Use HTTP verbs to implement CRUD

• Provide 2 kind of web service

• Human Web

• Programmable Web

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HTTP Request Methods

• Verbs:

• OPTIONS

• HEAD

• GET

• POST

• PUT

• DELETE

• TRACE

• CONNECT

• PATCH

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HTTP Request Methods

• Safe method: just get information, doesn’t change anything.

• GET, HEAD

• Idempotent methods: multiple identical requests should have the same effect as a single request.

• GET, HEAD, PUT, DELETE, OPTIONS, TRACE

!• We focus on: GET, POST, DELETE, PUT

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Details of REST Style

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Build REST from Everything

• There are two thoughts when we want build something:

• Nothing we have, we start from bringing in.

• Everything we have, we start from cutting down.

!• For REST, the author made some cut off on the former web style.

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RESTful Binding

• Client-Server

• Separate the system into client and server

• Client call request, send it to server

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RESTful Binding

• Stateless

• Request shall contain all the information it needs.

• Server identify requests by the info it stored in, not some info on the server.

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RESTful Binding

• Cacheable

• Data in the request should marked as either cacheable or not, in a sensitive or insensitive way, so that client can cache the data.

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RESTful Binding

• Uniform Interface

• Optimize the structure

• Light coupling

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RESTful Binding

• Layered System

• Simplify the system

• Make high performance possible

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RESTful Binding

• Code on Demand

• Expand system

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REST Quick Tips

• Use HTTP Verbs to mean something: GET, PUT, DELETE, POST

• Provide sensible resource names

• Use HTTP response code to indicate status

• Offer JSON and XML

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HTTP Methods

• We will only discuss the most useful four methods here:

• GET

• PUT

• POST

• DELETE

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HTTP Methods: GET

# Add bookmark

GET /bookmarks/add_bookmark?href=http%3A%2F%2F

www.example.org%2F2009%2F10%2F10%2Fontes.html HTTP/1.1

Host: www.example.org

# Add cart

GET /add_cart?pid=1234 HTTP/1.1

Host: www.example.org

# Delete note

GET /notes/delete?id=1234 HTTP/1.1

Host: www.example.org

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HTTP Methods: PUT

• PUT will only be used when client can decide the URI or resource.

!# Request

PUT /user/smith/address/home_address HTTP/1.1

Host: www.example.com

Content-type: application/xml;charset=UTF-8

<address>

<street>1, Main Street</street>

<city>New York</city>

</address>

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HTTP Methods: PUT

# Response

HTTP/1.1 201 Created

Location: http://www.example.org/user/smith/address/home_address

Content-Location: http://www.example.org/user/smith/address/home_address

Content-Type: application/xml;charset=UTF-8

<address>

<id>urn:example:user:smith:address:1</id>

<atom>link rel=“self” href=“http://www.example.org/user/smith/address/home_address”/>

<street>1, Main Street</street>

<city>New York</city>

</address>

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HTTP Methods: POST

• Create new resource if we don’t know the URI

• Update resource(s) using controller

• Run research which has too many parameters

• Other actions which are not safe

# Request

POST /user/smith HTTP/1.1

Host: www.example.com

Content-type: application/xml;charset=UTF-8

Slug: Home Address

<address>

<street>1, Main Street</street>

<city>New York</city>

</address>

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HTTP Methods: POST

# Response

HTTP/1.1 201 Created

Location: http://www.example.org/user/smith/address/home_address

Content-Location: http://www.example.org/user/smith/address/home_address

Content-Type: application/xml;charset=UTF-8

<address>

<id>urn:example:user:smith:address:1</id>

<atom>link rel=“self” href=“http://www.example.org/user/smith/address/home_address”/>

<street>1, Main Street</street>

<city>New York</city>

</address>

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HTTP Methods: DELETE

• DELETE a resource on the web.

!# Request

DELETE /users/john HTTP/1.1

Host: www.example.com

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Resource Naming

• To name a resource to make it readable and programmable

• URI: the name of resource as well as an address on the web

• A RESTful URI should refer to a resource that is a thing, not an action.

• Resource:

• Users of the system

• Courses in which a student is enrolled

• A user’s timeline of posts

• The users that follow another user (some kind of relationship)

• An article or a news on the web

• etc…

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Resource Naming

• Some examples:

• To insert/create a new customer in the system:

• POST http://example.com/customers

• To read a customer with Customer ID #12345

• GET http://example.com/customers/12345

• the same URI would be used for PUT & DELETE, to update and delete

• For reading , updating, deleting, product #12345:

• GET/PUT/DELETE http://example.com/pruducts/12345

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Resource Naming

• More examples:

• To create an order for a customer:

• POST http://example.com/customers/12345/orders

• GET http://example.com/customers/12345/orders

• What will it return ?

• POST http://example.com/customers/12345/orders/2334/lineitems

• What will this return ?

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Resource Naming

• More and more real examples:

• Twitter: https://dev.twitter.com/docs/api

• Facebook: http://develpoers.facebook.com/docs/api/

• LinkedIn: https://developer.linkedin.com/apis

• more…

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RESTful API Demo

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Build a website

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Build a set of API

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Programming Languages and Frameworks

• Java

• PHP

• Python

• Ruby

• JavaScript (Node.js)

• C#

• etc…

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Thanks for your listening !