REST with JAX-RS

An introduction to RESTful web services in Java using JAX-RS

Transcript

1. ______/\\\\\\\\\\\_____/\\\\\\\\\_____/\\\_______/\\\________________/\\\\\\\\\_________/\\\\\\\\\\\___ ! _____\/////\\\///____/\\\\\\\\\\\\\__\///\\\___/\\\/_______________/\\\///////\\\_____/\\\/////////\\\_ ! _________\/\\\______/\\\/////////\\\___\///\\\\\\/________________\/\\\_____\/\\\____\//\\\______\///__ ! _________\/\\\_____\/\\\_______\/\\\_____\//\\\\_______/\\\\\\\\__\/\\\\\\\\\\\/______\////\\\_________ ! _________\/\\\_____\/\\\\\\\\\\\\\\\______\/\\\\______\////////___\/\\\//////\\\_________\////\\\______! _________\/\\\_____\/\\\/////////\\\______/\\\\\\_________________\/\\\____\//\\\___________\////\\\___! __/\\\___\/\\\_____\/\\\_______\/\\\____/\\\////\\\_______________\/\\\_____\//\\\___/\\\______\//\\\__! _\//\\\\\\\\\______\/\\\_______\/\\\__/\\\/___\///\\\_____________\/\\\______\//\\\_\///\\\\\\\\\\\/___! __\/////////_______\///________\///__\///_______\///______________\///________\///____\///////////_____ ! ____/\\\\\\\\\______/\\\\\\\\\\\\\\\_____/\\\\\\\\\\\_____/\\\\\\\\\\\\\\\_ ! __/\\\///////\\\___\/\\\///////////____/\\\/////////\\\__\///////\\\/////__ ! _\/\\\_____\/\\\___\/\\\______________\//\\\______\///_________\/\\\_______ ! _\/\\\\\\\\\\\/____\/\\\\\\\\\\\_______\////\\\________________\/\\\_______! _\/\\\//////\\\____\/\\\///////___________\////\\\_____________\/\\\_______! _\/\\\____\//\\\___\/\\\_____________________\////\\\__________\/\\\_______! _\/\\\_____\//\\\__\/\\\______________/\\\______\//\\\_________\/\\\_______! _\/\\\______\//\\\_\/\\\\\\\\\\\\\\\_\///\\\\\\\\\\\/__________\/\\\_______! _\///________\///__\///////////////____\///////////____________\///________! with! 2009-09-15! Andreas Bjärlestam!
2. Andreas Bjärlestam mailto:andreas@bjarlestam.com http://andreas.bjarlestam.com http://twitter.com/bjarlestam
3. Attribution: http://www.flickr.com/photos/noahbulgaria/270090287 REST?
4. Pragmatic explanation   Use HTTP the way it was designed to be used   Take advantage of the good things in HTTP   By following a set of constraints
5. Constraints in REST •  Give everything its own URI •  Communicate with a standard set of methods •  Communicate with Media Types •  Link your resources together •  Avoid session state •  Support caching * This is a very simplified version of the real REST constraints, for the real stuff read Roy Fieldings dissertation
6. JAX-RS (JSR 311) Java API for building RESTful services
7. JAX-RS Based on POJOs with Annotations
8. JAX-RS Makes the developer focus on URLs, HTTP methods and Media Types.
9. Lets code…
10. @Path @Path("location") public class LocationResouce { }
11. @GET, @PUT, @POST @Path("location") public class LocationResouce { @GET @Produces("application/xml") public String getLocation() { return "<location>I’m in Sweden</location>"; } }
12. curl
13. @PathParam, @QueryParam @Path("location") public class LocationResouce { @GET @Path("{user}") @Produces("application/xml") public String getLocation(@PathParam("user") String user) { return "<location>” + user + " is in Sweden</location>"; } }
14. JAXB @Path("location") public class LocationResouce { @GET @Path("{user}") @Produces("application/xml") public Location getLocation(@PathParam("user") String user) { return new Location("59.3", "18"); } }
15. JAXB @XmlRootElement public class Location { public String lattitude; public String longitude; public Date timestamp; . . . }
17. @Produces and Media Types @Path("location") public class LocationResouce { @GET @Path("{user}") @Produces({"application/xml", "application/json"}) public Location getLocation(@PathParam("user") String user) { return new Location("59.3", "18"); } }
19. @Context, UriInfo and UriBuilder @Path("location") public class LocationResouce { @Context UriInfo uriInfo; . . . @POST @Consumes("application/x-www-form-urlencoded") public Response saveLocation(@FormParam("user") String user) { locations.put(user, new Location("59.3", "18")); UriBuilder uriBuilder = uriInfo.getAbsolutePathBuilder(); URI userUri = uriBuilder.path(user).build(); return Response.created(userUri).build(); } }
21. Cache Control @GET @Path("{user}") @Produces({"application/xml", "application/json"}) public Response getLocation(@PathParam("user") String user) { Location l = locations.get(user); CacheControl cc = new CacheControl(); cc.setMaxAge(500); Response.ResponseBuilder builder = Response.ok(l); builder.cacheControl(cc); return builder.build(); }
23. For the interested
24. For the interested   Roy Fieldings PhD dissertation, see ch 5 –  http://www.ics.uci.edu/~fielding/pubs/dissertation/top.htm   Roy Fieldings blog –  http://roy.gbiv.com/untangled/   Mark Hadleys blog –  http://weblogs.java.net/blog/mhadley/   Mark Nottinghams blog –  http://www.mnot.net   Stefan Tilkovs blog –  http://www.innoq.com/blog/st/
25. Extra slides
26. JAX-RS JSR 311 Version 1.0 was finalized in september 2008 Version 1.1 is planned to be part of JEE6
27. JAX-RS Several implementations available Sun Jersey JBoss RestEasy Restlets Apache CXF Triaxrs Apache WINK
28. Serendipity By giving everything a URL, sticking to a Uniform Interface and linking your resources you make the chances of reuse in unexpected ways higher
29. Statelessness •  Better scaling –  No session storage on server –  Any server in a cluster can handle any request –  The resources can safely be cached •  More reliable –  A client can safely re-send a request •  Better resource reuse –  The resources can safely be linked to
30. Caching
31. Client Proxy Cache Client Client Server Proxy Cache Client Reverse Proxy Cache Client Cache Client Cache Client Cache Client Cache
32. “The best requests are those that not even reach me.” - Anonymous overloaded Server
33. 50 requests/second = 3000 requests/minute setting max-age=60 (seconds) can then save you 2999 requests
34. Caching   GET can be cached while POST can't (safely)   Specify max-age –  Use max-age cache control header   Split data according to freshness requirement   Support conditional GET –  Get if modified since –  E-tags