RestFull Webservices with JAX-RS
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The document discusses developing RESTful web services using JAX-RS. It describes how JAX-RS allows identifying resources with URIs, communicating with standard HTTP methods, supporting multiple representations through content negotiation, and linking resources together through embedded URIs. Resources are represented as Java POJO classes annotated with JAX-RS annotations.
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RestFull Webservices with JAX-RS
- 1. Sabyasachi Ghosh, Senior Application Engneer Oracle India, @neilghosh Developing RESTful Web services with JAX-RS
- 2. Java API for RESTful Web Services (JAX-RS) Standard annotation-driven API that aims to help developers build RESTful Web services in Java
- 3. 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
- 4. Give everything an ID
- 5. Standard set of methods
- 9. ID is a URI http://example.com/widgets/foo http://example.com/customers/bar http://example.com/customers/bar/orders/2 http://example.com/orders/101230/customer
- 10. Resources are identified by URIs Resource == Java class POJO
- 11. No required interfaces ID provided by @Path annotation Value is relative URI, base URI is provided by deployment context or parent resource
- 12. Embedded parameters for non-fixed parts of the URI
- 13. Annotate class or “sub-resource locator” method
- 14. Resources are identified by URIs @Path("orders/{order_id}") public class OrderResource { @GET @Path("customer") CustomerResource getCustomer( @PathParam(“order_id”)int id ) {...} }
- 15. Standard Set of Methods Purpose Method Remove DELETE Update or create with a known ID PUT Update or create without a known ID POST Read, possibly cached GET
- 16. Standard Set of Methods Annotate resource class methods with standard method @GET , @PUT , @POST , @DELETE , @HEAD
- 17. @HttpMethod meta-annotation allows extensions, e.g. WebDAV JAX-RS routes request to appropriate resource class and method
- 18. Flexible method signatures, annotations on parameters specify mapping from request
- 19. Return value mapped to response
- 20. Standard Set of Methods @Path("properties/ {name} ") public class SystemProperty { @GET Property get(@PathParam(" name ") String name) {...} @PUT Property set(@PathParam(" name ") String name, String value ) {...} }
- 21. Parameters Template parameters and Regular expressions @Path("customers/ {firstname}-{lastname} ") @Path(" { id : \\d+} ") Matrix Parameters example.cars.com/mercedes/e55;color=black/2006 Query Paremetsrs DELETE /orders/233?cancel=true
- 22. Multiple Representations Offer data in a variety of formats XML
- 23. JSON
- 25. Support content negotiation Accept header GET /foo Accept: application/json
- 27. Content Negotiation: Accept Header Accept: application/xml Accept: application/json;q=1.0, text/xml;q=0.5, application/xml;q=0.5, @GET @Produces({"application/xml","application/json"}) Order getOrder(@PathParam(" order_id ") String id) { ... } @GET @Produces("text/plain") String getOrder2(@PathParam("order_id") String id) { ... }
- 28. Content Negotiation: URL-based @Path("/orders") public class OrderResource { @Path("{orderId}.xml") @Produces(“application/xml”) @GET public Order getOrderInXML(@PathParam("orderId") String orderId) { . . . } @Path("{orderId}.json") @Produces(“application/json”) @GET public Order getOrderInJSON(@PathParam("orderId") String orderId) { . . . } }
- 29. Content Negotiation import javax.ws.rs.GET; import javax.ws.rs.Path; import javax.ws.rs.Produces; import javax.ws.rs.PathParam; @Path("/actor/{id}") @GET @Produces("application/json") @PathParam("id") import javax.inject.Inject; import javax.enterprise.context.RequestScoped; @RequestScoped public class ActorResource { @Inject DatbaseBean db; public Actor getActor( int id) { return db.findActorById(id); } }
- 30. Link Things Together <order self=" http://example.com/orders/101230 "> <customer ref=" http://example.com/customers/bar "> <product ref=" http://example.com/products/21034 "/> <amount value="1"/> </order>
- 31. 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>
- 32. Responses Contain Links UriInfo provides information about deployment context, the request URI and the route to the resource
- 33. UriBuilder provides facilities to easily construct URIs for resources
- 34. 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);
- 35. Responses Contain Links UriBuilder builder = UriBuilder.fromPath("/customers/{id}"); builder.scheme("http") .host("{hostname}") .queryParam("param={param}"); http://{hostname}/customers/{id}?param={param} UriBuilder clone = builder.clone(); URI uri = clone.build("example.com", "333", "value"); http://example.com/customers/333?param=value
- 36. Response codes and Exception Successful HTTP : 200 to 399 200 – OK 204 – No Content Standard HTTP error : 400 to 599 404 – Not Found 406 - Not Acceptable 405 - Method Not Allowed java.lang.Exception java.lang.RuntimeException javax.ws.rs.WebApplicationException throw new WebApplicationException(Response.Status.NOT_FOUND);
- 37. Stateless Communications Long lived identifiers
- 38. Avoid sessions
- 39. Everything required to process a request contained in the request
- 40. Deployment JAX-RS application packaged in WAR like a servlet
- 41. 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
- 42. an init-param identifies the Application subclass Resource classes and providers can access Servlet request, context, config and response via injection
- 43. JAX-RS 1.1 Integration with Java EE 6 – Servlets 3.0 No or Portable “web.xml” <web-app> <servlet> <servlet-name>Jersey Web Application</servlet-name> <servlet-class> com.sun.jersey.spi.container.servlet.ServletContainer </servlet-class> <init-param> <param-name>javax.ws.rs.Application</param-name> <param-value>com.foo.MyApplication</param-value> </init-param> </servlet> <servlet-mapping> <servlet-name>Jersey Web Application</servlet-name> <url-pattern>/ resources /*</url-pattern> </servlet-mapping> </web-app> public class MyApplication extends javax.ws.rs.core.Application { } @ApplicationPath(“resources”)
- 44. JAX-RS Summary Java API for building RESTful Web Services
- 45. POJO based
- 47. Server-side API
- 48. HTTP-centric
- 49. JAX-RS 1.1 Jersey Client-side API Consume HTTP-based RESTful Services
- 50. Easy-to-use Better than HttpURLConnection! Reuses JAX-RS API Resources and URI are first-class citizens Not part of JAX-RS yet com.sun.jersey.api.client
- 51. JAX-RS 1.1 Jersey Client API – Code Sample Client client = Client.create(); WebResource resource = client.resource(“...”); //curl http://example.com/base String s = resource.get(String.class); //curl -HAccept:text/plain http://example.com/base String s = resource. accept(“text/plain”). get(String.class); http://blogs.oracle.com/enterprisetechtips/entry/consuming_restful_web_services_with
- 52. JAX-RS 1.1 WADL Representation of Resources Machine processable description of HTTP-based Applications
- 53. Generated OOTB for the application <application xmlns="http://research.sun.com/wadl/2006/10"> <doc xmlns:jersey="http://jersey.dev.java.net/" jersey:generatedBy="Jersey: 1.1.4.1 11/24/2009 01:37 AM"/> <resources base=" http://localhost:8080/HelloWADL/resources/ "> <resource path="generic"> <method id="getText" name=" GET "> <response> <representation mediaType="text/plain"/> </response> </method> <method id="putText" name=" PUT "> <request> <representation mediaType="text/plain"/> </request> </method> </resource> </resources> </application>
- 56. jersey.java.net
- 57. jax-ws.java.net/
- 58. Demo
- 59. Sabyasachi Ghosh, Senior Application Engneer Oracle India, @neilghosh Developing RESTful Web services with JAX-RS Thank You