Introduction to JAX-RS @ SIlicon Valley Code Camp 2010

<Insert Picture Here> Introduction to JAX-RS Jitendra Kotamraju Oct 2010

What this presentation is about ? • Not the REST style per se – But, briefly ... • The basics of JAX-RS 2

Agenda • What is JAX-RS ? • JAX-RS Resources • Standard Methods (uniform interface) • JAX-RS Representations • Lots of demos using JAX-RS API – @Path, HTTP methods, @Produces/@Consumes – XML, JSON, @xxParam, Response, Application, – Sub-resource locators, Injection etc 3 ©2010 Oracle Corporation

Very Short REST Primer: Buy This Book 4

Java API for RESTful Web Services (JAX-RS) Standard annotation-driven API that aims to help developers build RESTful Web services in Java 7

Status of JAX-RS • JSR 311: JAX-RS 1.1 released Nov 2009 • Part of Java EE 6; Not part of the Web profile! • Specifies integration with technologies: – CDI 1.0 – EBJ 3.1 – Servlet 3.0 • Jersey implementation shipped with GlassFish 3.x • 7 implementations – Apache CXF, Apache Wink, eXo, Jersey, RESTEasy, Restlet, Triaxrs 8

Sample JAX-RS application GlassFish hello.war GET /hello/world HTTP/1.1 JAX-RS resource HTTP/1.1 200 OK Content-Type: text/xml <hello world/> 9

RESTful Application Cycle Resources are identified by URIs ↓ Clients communicate with resources via requests using a standard set of methods ↓ Requests and responses contain resource representations in formats identified by media types ↓ Responses contain URIs that link to further resources 10

Resources are identified by URIs http://example.com/widgets/foo http://example.com/customers/bar http://example.com/customers/bar/orders/2 http://example.com/orders/101230/customer 11

JAX-RS Resources • Resource == Java class – POJO, EJB Stateless, Singleton Session Beans – No required interfaces • ID provided by @Path annotation – Value is relative URI, base URI is provided by deployment context or parent resource – Embedded parameters for non-fixed parts of the URI – Annotate class or “sub-resource locator” method 12 ©2010 Oracle Corporation

JAX-RS Sub-resources • Root resources can declare sub-resources that will match the unmatched part of the URI path • Root resources implement sub-resource locator methods 14

JAX-RS Sub-resources @Path("properties") public class Props { @GET @Path("{name}") Prop getProperty(@PathParam("name")String p){…} } GET http://.../context/properties/java.home 15 ©2010 Oracle Corporation

JAX-RS Sub-resources @Path("properties") public class Props { @GET @Path("java.home") Prop getProperty() {…} @Path("{name}") Object getProp(@PathParam("name")String name){ return new Dyna(name); } } public class Dyna { @GET Prop getProperty() {…} } 16 ©2010 Oracle Corporation

JAX-RS Sub-resources @Path("properties") public class Props { @GET @Path("java.home") Prop getProperty() {…} @Path("{name}") Object getProp(@PathParam("name")String name){ return new Dyna(name); } } public class Dyna { @GET Prop getProperty() {…} } GET http://.../context/properties/java.home 17 ©2010 Oracle Corporation

JAX-RS Sub-resources @Path("properties") public class Props { @GET @Path("java.home") Prop getProperty() {…} @Path("{name}") Object getProp(@PathParam("name")String name){ return new Dyna(name); } } public class Dyna { @GET Prop getProperty() {…} } GET http://.../context/properties/java.tmp.dir 20 ©2010 Oracle Corporation

JAX-RS Sub-resources summary • Sub-resource classes are processed at runtime • Warning: easy to confuse sub-resource methods with sub-resource locators 23

Standard Set of Methods Method Purpose GET Read, possibly cached POST Update or create without a known ID PUT Update or create with a known ID DELETE Remove 24

JAX-RS Methods • Annotate resource class methods with standard method – @GET, @PUT, @POST, @DELETE, @HEAD – @HttpMethod meta-annotation allows extensions, e.g. WebDAV • JAX-RS routes request to appropriate resource class and method • Flexible method signatures, annotations on parameters specify mapping from request • Return value mapped to response 25

JAX-RS HTTP Methods @Path("properties/{name}") public class Props { @GET Prop get(@PathParam("name") String name) {...} @PUT Prop set(@PathParam("name") String name, String value) {...} } 26 ©2010 Oracle Corporation

Resource Representations • Representation format identified by media type. E.g.: – XML - application/properties+xml – JSON - application/properties+json – (X)HTML+microformats - application/xhtml+xml • JAX-RS automates content negotiation – GET /foo Accept: application/properties+json 27

Resource Representations • Annotate methods or classes with static capabilities – @Produces, @Consumes • Use Variant, VariantListBuilder and Request.selectVariant for dynamic capabilities – Also supports language and encoding 28

JAX-RS Resource Representations @GET @Produces("application/properties+xml") Prop getXml(@PathParam("name") String name) { ... } @GET @Produces("text/plain") String getText(@PathParam("name") String name) { ... } 29

JAX-RS Resource Representations @POST @Consumes("application/xml") @Produces({"application/xml","application/json"}) Customer getCustomer(Source id) { … return customer; } @XmlRootElement class Customer { public String first; public String last; } 30

Responses Contain Links HTTP/1.1 201 Created Date: Wed, 03 Jun 2009 16:41:58 GMT Server: Apache/1.3.6 Location: http://example.com/properties/foo Content-Type: application/order+xml Content-Length: 184 <property self="http://example.com/properties/foo"> <parent ref="http://example.com/properties/bar"/> <name>Foo</name> <value>1</value> </order> 31

Responses Contain Links • UriInfo provides information about deployment context, the request URI and the route to the resource • UriBuilder provides facilities to easily construct URIs for resources 32

Responses Contain Links @Context UriInfo i; SystemProperty p = ... UriBuilder b = i.getBaseUriBuilder(); URI u = b.path(SystemProperties.class) .path(p.getName()).build(); List<URI> ancestors = i.getMatchedURIs(); URI parent = ancestors.get(1); 33 ©2010 Oracle Corporation

Demos 34

The future of JAX-RS • Possible features in scope for a JAX-RS 2.0 effort – Client API – Declarative hyperlinking – Model View Controller – Quality of Source – Form validation – Asynchronous/Comet/WebSocket – Improved integration with JSR-330 and @Inject – JAX-RS Modules 35

Information • JSR-311: http://jsr311.dev.java.net/ • http://jersey.dev.java.net • mailto:users@jersey.dev.java.net • http://glassfish.dev.java.net 36

Questions ? 37

Servlet JAX-RS application packaged in WAR like a servlet For JAX-RS aware containers web.xml can point to Application subclass For non-JAX-RS aware containers web.xml points to implementation-specific Servlet; and an init-param identifies the Application subclass Resource classes and providers can access Servlet request, context, config and response via injection 38 ©2010 Oracle Corporation

Java EE Resource class can be an EJB session or singleton bean Providers can be an EJB stateless session or singleton bean JAX-RS annotations on local interface or no-interface bean If JCDI (JSR 299) also supported then Resource classes can be JCDI beans Providers can be JCDI beans with application scope Full access to facilities of native component model, e.g. resource injection 39

Introduction to JAX-RS @ SIlicon Valley Code Camp 2010

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Introduction to JAX-RS @ SIlicon Valley Code Camp 2010 Presentation Transcript

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