REST made simple with Java
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This document provides an overview of REST and how to implement it with Java using frameworks like JAX-RS. It discusses REST principles like resources having identifiers and exposing a uniform interface. It shows how to define Java REST services using annotations to map HTTP methods to methods. It also covers writing custom entity providers to support different media types and handling requests, responses, and exceptions.
![Niklas Gustavsson [email_address] http://protocol7.com http://twitter.com/protocol7](https://image.slidesharecdn.com/sdc-2009-rest-090330035524-phpapp01/85/REST-made-simple-with-Java-2-320.jpg)
![@Provider @Produces("text/calendar") public class TimeReportICalWriter implements MessageBodyWriter<TimeReport> { public void writeTo(TimeReport t, Class<?> type, Type genericType,Annotation[] annotations,MediaType mediaType,MultivaluedMap<String, Object> httpHeaders, OutputStream entityStream) { PrintWriter wr = new PrintWriter(entityStream); ... for(TimeRange range : t.getRanges()) { wr.println("BEGIN:VFREEBUSY"); wr.println("DTSTART:" + DF.format(range.getStartTime())); wr.println("DTEND:" + DF.format(range.getEndTime())); wr.println("SUMMARY:" + range.getDescription()); wr.println("END:VFREEBUSY"); } ... }](https://image.slidesharecdn.com/sdc-2009-rest-090330035524-phpapp01/85/REST-made-simple-with-Java-45-320.jpg)
![[email_address]](https://image.slidesharecdn.com/sdc-2009-rest-090330035524-phpapp01/85/REST-made-simple-with-Java-58-320.jpg)
REST made simple with Java
- 1. SDC 2008 REST made simple with Java
- 2. Niklas Gustavsson [email_address] http://protocol7.com http://twitter.com/protocol7
- 3. REST made simple with Java
- 4. REST?
- 5. HTTP 1.1
- 10. Principles
- 11. Principles Everything is a resource
- 12. Principles A resource has an identifier http://example.com/customers/1453
- 13. Principles We transfer representations
- 14. Principles All resources expose a uniform interface GET, POST, PUT, DELETE
- 15. Principles Hypermedia as the engine of application state
- 16. Principles Client-server, Stateless, Cacheable, Layered
- 17. Why?
- 18. Why? It's easy! Well, it's not
- 19. Why? It's what the cool kids use
- 20. Why? Web has been successful, copy!
- 21. Why? It's what others use
- 22. Why? Interoperability on the right level
- 25. Jersey http://jersey.dev.java.net Restlets http://www.restlet.org RESTeasy http://www.jboss.org/resteasy CXF http://cxf.apache.org
- 26. POJO based Annotation heavy
- 27. Resources
- 28. Code! Show me the code!
- 29. public class TimeReportService { private TimeReportDao reportDao; public TimeReport getReport(String username) { return reportDao.forUser(username); } public void saveReport(TimeReport report) { reportDao.update(report); } ... }
- 30. Request mapping
- 31. @Path("report") public class TimeReportService { private TimeReportDao reportDao; @GET public TimeReport getReport(String username) { return reportDao.forUser(username); } @PUT public void saveReport(TimeReport report) { reportDao.update(report); } ... }
- 33. public class TimeReportApplication extends Application { @Override public Set<Class<?>> getClasses() { Set<Class<?>> resources = new HashSet<Class<?>>(); resources.add(TimeReportService.class); return resources; } }
- 34. Path parameters and contexts
- 35. @Path("{username}/report") public class TimeReportService { @GET public TimeReport getReport(@PathParam("username") String username) { return reportDao.forUser(username); } ... } http://example.com/niklas/report
- 36. @GET public TimeReport getReport(@Context SecurityContext sc) { if(sc.isSecure()) { Principal user = sc.getUserPrincipal(); return reportDao.forUser(user.getName()); } else { ... throw error, redirect to login } }
- 37. @GET public TimeReport getReport(@CookieParam("username") String username) { return reportDao.forUser(username); }
- 39. Any media type is allowed XML, JSON, text/plain, Binary files, ...
- 40. Entity providers MessageBodyReader, MessageBodyWriter
- 43. Writing your own Entity provider
- 44. BEGIN:VFREEBUSY DTSTART:20090324T080000Z DTEND:20090324T170000Z DTSTAMP:20090316T123136Z UID:[email protected] SUMMARY:SDC2009 END:VFREEBUSY
- 45. @Provider @Produces("text/calendar") public class TimeReportICalWriter implements MessageBodyWriter<TimeReport> { public void writeTo(TimeReport t, Class<?> type, Type genericType,Annotation[] annotations,MediaType mediaType,MultivaluedMap<String, Object> httpHeaders, OutputStream entityStream) { PrintWriter wr = new PrintWriter(entityStream); ... for(TimeRange range : t.getRanges()) { wr.println("BEGIN:VFREEBUSY"); wr.println("DTSTART:" + DF.format(range.getStartTime())); wr.println("DTEND:" + DF.format(range.getEndTime())); wr.println("SUMMARY:" + range.getDescription()); wr.println("END:VFREEBUSY"); } ... }
- 48. Deployment
- 50. JAX-RS limitations Lifecycle support
- 51. JAX-RS limitations Weak support for links, caching, method tunneling
- 52. JAX-RS limitations Accept based content negotiation only http://example.com/report http://example.com/report.xml http://example.com/report.cal http://example.com/report.json
- 53. JAX-RS limitations Limited security support
- 54. JAX-RS limitations Leaky abstraction
- 55. Try it out! And have a look at the alternatives
- 56. Want more?
- 57. Questions?
- 58. [email_address]
- 59. Attributions http://www.flickr.com/photos/psd/421186578/ http://www.flickr.com/photos/sineout/2491569707/ http://www.flickr.com/photos/apelad/sets/72157594388426362/ http://www.flickr.com/photos/goopymart/289959670