Creating a Web of Data with Restlet

Creating a Web of Data with Restlet

Andrew Newman

1Monday, 8 December 2008

REST ArchitectureResource Oriented Analysis and Design (ROAD)

Stateless Access

Where Everything is a Resource

Identified by URI

With Different Representations

Linked Together

2Monday, 8 December 2008

Restlet OveviewGWT, Client and Server APIs

Standalone, App Servers, Oracle, OSGi, Spring

HTTP, SMTP, POP3, JDBC, File Connectors

JSON, XML, HTML, Atom Representations

Integration with Groovy, JPA, Seam, Struts Hibernate

3Monday, 8 December 2008

A little bit of HTTPVerb Action

GET Return the entity

POST Server create/modify entity

PUT Client create/modify entity

DELETE X Delete an entity

HEAD Entity metadata (not data)

OPTIONS ? Methods supported on entity

4Monday, 8 December 2008

Restlet ModelUniform

Restlet

Application

Filter FinderConnector Router

Component Redirector

Client Server Guard

Transformer

Route

5Monday, 8 December 2008

Restlet Model• Reference - Mutable java.net.URI

• Request - Client Request

• Response - Server Response

• MediaType - Mime Types e.g. text/html, application/xml

• Resource - Anything with a Reference e.g. video, document, collection

• Variant - Metadata about a representation.

• Representation - The current state/value of a Resource.

6Monday, 8 December 2008

Resource APIGET Representation represent(Variant)

POST void acceptRepresentation(Representation)

PUT void storeRepresentation(Representation)

DELETE void removeRepresentations()

HEAD Calls GET without stream.

OPTIONS Updates Response’s getAllowedMethods

7Monday, 8 December 2008

Applications and Components// Create Application for http://localhost/helloWorldApplication application = new Application() { public synchronized Restlet createRoot() { Router router = new Router(getContext()); // Attach a resource router.attach("helloWorld", HelloWorldResource.class); return router; }};// Create the component and attach the applicationComponent component = new Component();component.getServers().add(Protocol.HTTP);component.getDefaultHost().attach(application);// Start the web servercomponent.start();

8Monday, 8 December 2008

Data and Resourcespublic HelloWorldResource(Context context, Request request, Response response) { super(context, request, response); // Declare all kind of representations supported by the resource getVariants().add(new Variant(MediaType.TEXT_PLAIN));}

// Respond to GETpublic Representation represent(Variant variant) throws ResourceException { Representation representation = null; // Generate a representation according to the variant media type. if (MediaType.TEXT_PLAIN.equals(variant.getMediaType())) { representation = new StringRepresentation("hello, world", MediaType.TEXT_PLAIN); } return representation;}

9Monday, 8 December 2008

A Bit More HTTPGET /index HTTP/1.1 Host: www.realestate.com User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.12)... Accept: text/xml,application/xml,application/xhtml+xml,text/html;q=0.9,... Accept-Language: us,en;q=0.5 Accept-Encoding: gzip,deflate Accept-Charset: ISO-8859-15,utf-8;q=0.7,*;q=0.7 Keep-Alive: 300 Connection: keep-alive

10Monday, 8 December 2008

Drop the DotYeshttp://realestate.com/house/1 + type Nohttp://realestate.com/house/1.htmlhttp://realestate.com/house/1.xmlhttp://realestate.com/house/1.jsonhttp://realestate.com/house/1.png

11Monday, 8 December 2008

No iPhoneYeshttp://realestate.com/house/1 + user-agent Nohttp://www.realestate.com/house/1http://iphone.realestate.com/house/1http://iphone-v2.realestate.com/house/1http://n95-8GB-Black.realestate.com/house/1

12Monday, 8 December 2008

Client Side API// GET a resource from uri as a XML DOM.Response response = new Client(Protocol.HTTP).get(uri);DomRepresentation document = response.getEntityAsDom();// Specify content types.ClientInfo clientInfo = request.getClientInfo();List<Preference<MediaType>> preferenceList = new ArrayList<Preference<MediaType>>();preferenceList.add(new Preference<MediaType>(TEXT_XML));preferenceList.add(new Preference<MediaType>(APPLICATION_XML));preferenceList.add(new Preference<MediaType>(APPLICATION_XHTML_XML));preferenceList.add(new Preference<MediaType>(TEXT_HTML, 0.9f));clientInfo.setAcceptedMediaTypes(preferenceList);// Specify encodingsclientInfo.setAcceptedEncodings(Arrays.asList(new Preference<Encoding>(Encoding.GZIP));// Finally, GET.client.get(uri);

13Monday, 8 December 2008

Simple WebDAV

Directory Demo

See also: http://code.google.com/p/gogoego/

14Monday, 8 December 2008

Restlet and SpringConfigurableRestletResource<bean id="someResource" class="SomeResource" scope="prototype"> <property name="representationTemplates"> <map> <entry key-ref="TEXT_HTML" value-ref="htmlRep"/> <entry key-ref="APPLICATION_JSON" value-ref="jsonRep"/> <entry key-ref="APPLICATION_XML" value-ref="xmlRep"/> </map> </property></bean>

15Monday, 8 December 2008

Restlet and SpringFreemarkerRepresentationFactory<bean id="htmlRep" class="org.jrdf.query.server.FreemarkerRepresentationFactory"> <property name="templateName" value="dbLocal-html.ftl"/> <property name="freemarkerConfig" ref="freemarkerConfig"/></bean>

dbLocal-html.ftl<html><head> <title>Query Page -- Database ${database}</title></head><body> <h1> Query for database <i>${database}</i>...

16Monday, 8 December 2008

Restlet and SpringSpringRouter<bean id="router" class="org.restlet.ext.spring.SpringRouter"> <property name="attachments"> <map> <entry key="/databases"> <bean class="org.restlet.ext.spring.SpringFinder"> <lookup-method name="createResource" bean="listDbResource"/> </bean> </entry> <entry key="/databases/{database}"> <bean class="org.restlet.ext.spring.SpringFinder"> <lookup-method name="createResource" bean="queryDbResource"/> </bean> </entry> </map> </property></bean>

17Monday, 8 December 2008

Restlet and Springpublic Representation represent(Variant variant) { Representation rep = null; try { graphName = (String) getRequest().getAttributes().get("database"); if (getRequest().getResourceRef().hasQuery()) { queryString = getRequest().getResourceRef().getQueryAsForm(). getFirst("query").getValue(); } if (queryString == null) { rep = queryPageRepresentation(variant); } else { rep = queryResultRepresentation(variant); } getResponse().setStatus(SUCCESS_OK); } catch (Exception e) { getResponse().setStatus(SERVER_ERROR_INTERNAL, e, e.getMessage().replace("\n", "")); } return rep;}

18Monday, 8 December 2008

Linking Data

recipeID Desc. Cat.1 Chips Snack2 Ice Water Drink

recipeID Desc. Cat.1 Toast Snack2 Tea Drink

URIshttp://myfood.com/recipe/chipshttp://myfood.com/recipe/water

http://myfood.com/cat/snackhttp://myfood.com/cat/drink

URIshttp://yourfood.com/recipe/toasthttp://yourfood.com/recipe/teahttp://yourfood.com/cat/snackhttp://yourfood.com/cat/drink

MyFood.Com YourFood

19Monday, 8 December 2008

recipeID Desc. Cat.1 Chips Snack2 Ice Water Drink

recipeID Desc. Cat.1 Toast Snack2 Tea Drink

URIshttp://myfood.com/recipe/chipshttp://myfood.com/recipe/water

http://myfood.com/cat/snackhttp://myfood.com/cat/drink

URIshttp://yourfood.com/recipe/toasthttp://yourfood.com/recipe/teahttp://yourfood.com/cat/snackhttp://yourfood.com/cat/drink

MyFood.Com YourFood

Linking Data

?20Monday, 8 December 2008

Linking Datahttp://myfood.com/cat/snack

http://yourfood.com/cat/snack

http://myfood.com/recipe/chips

IsA

http://yourfood.com/recipe/toast

IsA

21Monday, 8 December 2008

Linking Datahttp://myfood.com/cat/snack

http://yourfood.com/cat/snack

isTheSameAs

http://myfood.com/recipe/chips

IsA

http://yourfood.com/recipe/toast

IsA

22Monday, 8 December 2008

Linking Datahttp://myfood.com/cat/snack

http://yourfood.com/cat/snack

isTheSameAs

http://myfood.com/recipe/chips

IsA

http://yourfood.com/recipe/toast

IsA

http://purl.org/recipeIsA

IsA

23Monday, 8 December 2008

Querying the WebUser at myFood.Com wants all the snack recipes:

1. Find all http://purl.org/recipe and http://myfood.com/cat/snack

recipe {my:chips, my:water}, snack {my:snack}

2. my:snack = your:snack

3. Query YourFood

recipe {your:toast, your:tea}, snack {your:tea}

4. Answer: {my:chips, your:toast}

24Monday, 8 December 2008

How do you Link Data?RDF (Linking URIs)

<my:chips> <rdfs:type> <purl:snack>

SPARQL (Querying)SELECT * FROM myfood, yourfood WHERE { ?recipe <rdfs:type> <purl:recipe> .?recipe <rdfs:type> <my:cat/snack> }

OWL (Adding Relationships)<my:cat/snack> <owl:sameAs> <your:cat/snack>

25Monday, 8 December 2008

Questions?

26Monday, 8 December 2008