Introduction to JAX-RS that I gave at Øredev 2009

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

6. Some HTTP history

7. Some HTTP history

8. HTTP used right

9. Constraints

10. Constraints Everything is a resource

11. Constraints A resource has an identifier http://example.com/reports/niklas

12. Constraints We transfer representations

13. Constraints All resources expose a uniform interface GET, POST, PUT, DELETE

14. Constraints Hypermedia as the engine of application state

15. Constraints Client-server, Stateless, Cacheable, Layered

16. Why?

17. Why? It's easy! Well, it's not

18. Why? It's what the cool kids use

19. Why? Web has been successful, copy!

20. Why? It's what others use

21. Why? Interoperability on the right level

22. Frameworks!

23. JAX-RS (aka JSR-311)

24. Jersey http://jersey.dev.java.net Restlets http://www.restlet.org RESTeasy http://www.jboss.org/resteasy CXF http://cxf.apache.org

25. POJO based Annotation heavy

26. Resources

27. Code! Show me the code!

28. public class TimeReportService { private TimeReportDao reportDao; public TimeReport getReport(String username) { return reportDao.forUser(username); } public void saveReport(TimeReport report) { reportDao.update(report); } ... }

29. Request mapping

31. @Path("reports") 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); } ... }

32. Parameters

33. @Path("reports/ {username} ") public class TimeReportService { @GET public TimeReport getReport(@PathParam("username") String username) { return reportDao.forUser(username); } ... } http://example.com/report/ niklas

34. @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 } }

35. @GET public TimeReport getReport(@CookieParam("username") String username) { return reportDao.forUser(username); }

36. Any media type is allowed XML, JSON, text/plain, binary, ...

37. Entity providers MessageBodyReader, MessageBodyWriter

39. Standard Entity providers

40. Writing your own Entity provider

41. BEGIN:VEVENT DTSTART:20091102T080000Z DTEND:20091106T170000Z SUMMARY:OREDEV END:VEVENT

42. @Provider @Produces(&quot;text/calendar&quot;) 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(&quot;BEGIN:VEVENT&quot;); wr.println(&quot;DTSTART:&quot; + DF.format(range.getStartTime())); wr.println(&quot;DTEND:&quot; + DF.format(range.getEndTime())); wr.println(&quot;SUMMARY:&quot; + range.getDescription()); wr.println(&quot;END:VEVENT&quot;); } ... }

43. Request Response ResponseBuilder

44. Exception Mapping

45. Application

47. public class TimeReportApplication extends Application { @Override public Set<Class<?>> getClasses() { Set<Class<?>> classes = new HashSet<Class<?>>(); classes .add(TimeReportService.class); classes .add(TimeReportICalWriter.class); return classes ; } }

48. Deployment

49. JAX-RS limitations

50. JAX-RS limitations Lifecycle support

51. JAX-RS limitations Conneg only http://example.com/report http://example.com/report.xml http://example.com/report.cal http://example.com/report.json

52. JAX-RS limitations Limited security support

53. JAX-RS limitations Leaky abstraction

54. JAX-RS limitations Weak support for links

55. Try it out! And have a look at the alternatives

56. Want more? http://github.com/protocol7/jax-rs-demo

57. Want more?

58. Questions?

59. [email_address]

60. 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