Making Java REST with JAX-RS 2.0

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A short introduction on how JAX-RS 2.0 supports REST, including HATEOAS.

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Making Java REST with JAX-RS 2.0

  1. 1. Making Java REST with JAX-RS 2.0 April 24, 2014 Dmytro Chyzhykov
  2. 2. Disclaimer The views and opinions expressed in this presentation expressed by the speaker are solely his own and do not necessary represent the views and opinions of companies he is working or worked for. 3
  3. 3. Agenda - What is REST? - REST Principles and JAX-RS 2.0 - Q & A 4
  4. 4. HTTP Response 200 OKJSON Media Type Client ServerHTTP GET Resources Request http://example.com Read more Hypertext Transfer Protocol -- HTTP/1.1 5
  5. 5. What is REST? 6
  6. 6. REST? 7
  7. 7. REST JEE7 Definition REpresentational State Transfer is an architectural style of client-server applications centered around the transfer of representations of resources through requests and responses. Serves to build loosely coupled, lightweight web services that are particularly well suited for creating APIs for clients spread out across the Internet. Was introduced and defined by Roy T. Fielding in his doctoral dissertation. Read more The Java EE 7 Tutorial: 29.1 What Are RESTful Web Services? 8
  8. 8. REST is... - An architectural style, not a technology - Everything is a Resource - Suitable for CRUD (Create/Read/Update/Delete) - Stateless by nature (excellent for distributed systems) - Cacheable (naturally supported by HTTP) - Composable code on demand applications 9
  9. 9. REST Principles - Give every thing its own ID - Link things together (HATEOAS) - Use standard HTTP methods - Resources can have multiple representations - Communicate statelessly - Support caching 10
  10. 10. Give every thing its own ID 11
  11. 11. Individual Resource ID http://habrahabr.ru/users/theshade/! https://twitter.com/fielding! https://api.github.com/teams/46059! Collection Resource ID https://api.github.com/teams/! https://twitter.com/fielding/followers! https://api.github.com/user/repos?page=2! http://ajax.googleapis.com/ajax/services/ search/web?v=1.0&q=Paris%20Hilton 12
  12. 12. JAXRS 2.0 resource example GET http://locahost:8080/articles/7! GET http://locahost:8080/articles/! GET http://locahost:8080/articles/?page=1! 13
  13. 13. JAXRS 2.0 resource example GET http://locahost:8080/articles/7! GET http://locahost:8080/articles/! GET http://locahost:8080/articles/?page=1! @Path("articles") public class ArticleResource { } 14
  14. 14. JAXRS 2.0 resource example GET http://locahost:8080/articles/7! GET http://locahost:8080/articles/! GET http://locahost:8080/articles/?page=1! @Path("articles") public class ArticleResource { @GET @Path("{id}") public Article read(@PathParam("id") int id) {…} } 15
  15. 15. JAXRS 2.0 resource example GET http://locahost:8080/articles/7! GET http://locahost:8080/articles/! GET http://locahost:8080/articles/?page=1! @Path("articles") public class ArticleResource { @GET @Path("{id}") public Article read(@PathParam("id") int id) {…} @GET public List<Article> list(@QueryParam("page") @DefaultValue("1") int page) {…} } 16
  16. 16. Article POJO public class Article { private Integer id; private String title; private String content; ! // Getters and setters go here } 17
  17. 17. Let's try $ curl -X GET http://localhost:8080/articles/7! {! "id": 7,! "title": "REST Individual Resource",! "content": "REST Individual Resource example"! } $ curl -X GET http://localhost:8080/articles/! [! {! "id": 7,! "title": "REST Individual Resource",! "content": "REST Individual Resource example"! }! ] 18
  18. 18. Link things together 19
  19. 19. HATEOAS HATEOAS is abbreviation for Hypermedia as the Engine of Application State.
 A hypermedia-driven site provides information to navigate the site's REST interfaces dynamically by including hypermedia links with the responses. Read more Why hypermedia APIs? and Understanding HATEOAS 20
  20. 20. Atom Links Style <article id="123"> <title>Hypermedia and JAX-RS 2.0</title> <content>JAX-RS 2.0 supports Hypermedia …</content> ! <link rel="self" href=“/articles/123/" /> <link rel="update" href=“/articles/123/" /> <link rel="delete" href=“/articles/123/" /> <link rel="list" href=“/articles/“ /> ! </article> Read more Atom Format Link Relation Extensions 21
  21. 21. Link Headers Style HTTP/1.1 200 OK Content-Type: application/xml Link: </articles/123/>; rel=self; Link: </articles/123/>; rel=update; Link: </articles/123/>; rel=delete; Link: </articles/>; rel=list; ! <article id="123"> <title>Hypermedia and JAX-RS 2.0</title> <content>JAX-RS 2.0 supports Hypermedia …</content> </article> Read more Web Linking:The Link Header Field 22
  22. 22. How to Imaging HATEOAS 23
  23. 23. How to Imaging HATEOAS 24
  24. 24. JAX-RS 2.0 HATEOAS @POST @Consumes({"application/json", "application/xml"}) @Produces({"application/json", "application/xml"}) public Response create(Article article) { Article created = articleDao.create(article); return Response .ok(created) .link("link-URI", “link-rel") .links(produceLinks(created)) .build(); } ! private Link[] produceLinks(Article article) {...} Read more javax.ws.rs.core.Link 25
  25. 25. Jersey 2.x HATEOAS public class Article { @InjectLinks({ @InjectLink(resource = ArticleResource.class, rel = "self", method = "read"), @InjectLink(resource = ArticleResorce.class, rel = "edit", method = "update"), @InjectLink(resource = ArticleResource.class, rel = "delete", method = "delete"), @InjectLink(resource = ArticleResource.class, rel = "list", method = “list") }) private List<Link> links; ! Read more Jersey 2.x Chapter 12. Declarative Hyperlinking 26
  26. 26. Let's try $ curl -X GET “http://localhost:8080/articles/123" { "id": 123, "title": "Hypermedia and JAX-RS 2.0", "content": "JAX-RS 2.0 supports Hypermedia …", "links": [ { "uri": "/articles/", "rel": "self" }, { "uri": "/articles/", "rel": "edit" }, { "uri": "/articles/", "rel": "delete" }, { "uri": "/articles", "rel": “list"}] } 27
  27. 27. Use standard HTTP methods Method Purpose GET Read representation of the specified resource POST Create or Update without a know ID PUT Update or Create with a know ID DELETE Remove HEAD GET with no response, just metadata OPTIONS Supported methods for the specified URL. 28
  28. 28. HTTP methods and JAX-RS 2.0 Method Annotation POST @POST GET @GET PUT @PUT DELETE @DELETE HEAD @HEAD OPTIONS @OPTIONS 29
  29. 29. Multiple Representations 30
  30. 30. Content Negotiation GET http://example.com/stuff Accept: application/xml, application/json, text/* Give me resource contents as (in priority): 1. XML 2. or JSON 3. or any text content type you can 4. or return 406 Not Acceptable Error 
 otherwise 31
  31. 31. Content Negotiation Example curl -X POST "http://localhost:8080/articles" -H "Content-Type: application/xml" -d "<article> <title>Conneg and JAX-RS 2.0</title> <content> JAX-RS 2.0 supports Conneg… </content> </article>" -H "Accept: application/json" { "id": 7, "title": "Conneg and JAX-RS 2.0", "content": "JAX-RS 2.0 supports Conneg …" } 32
  32. 32. Content Negotiation Example curl -X POST "http://localhost:8080/articles" -H "Content-Type: application/xml" -d "<article> <title>Conneg and JAX-RS 2.0</title> <content> JAX-RS 2.0 supports Conneg… </content> </article>" -H "Accept: application/json" { "id": 7, "title": "Conneg and JAX-RS 2.0", "content": "JAX-RS 2.0 supports Conneg …" } 33
  33. 33. Content Negotiation Example @POST @Consumes({"application/json", "application/xml"}) @Produces({"application/json", "application/xml"}) public Article create(Article article) { return articleDao.create(article); } 34
  34. 34. Language Negotiation GET http://example.com/stuff Accept-Language: en-us, en, ru Encoding Negotiation GET http://example.com/stuff Accept-Encoding: gzip, deflate 35
  35. 35. Communicate Statelessly 36
  36. 36. State is Bad Client Load Balancer Server 1 Sessions Server 3 Sessions Server 2 Sessions 37
  37. 37. State is Bad Client Load Balancer Server 1 Sessions Server 3 Sessions Server 2 Sessions Replication Replication 38
  38. 38. State is Bad Client Load Balancer Server 1 Sessions Server 3 Sessions Server 2 Sessions Replication Replication ItD oesN otScale 39
  39. 39. Communicate statelessly Client Load Balancer Server 1 Server 3 Server 2 Token Storage 40
  40. 40. Caching Support “The best requests are those that not even reach me” - Anonymous overloaded Server 41
  41. 41. Caching Benefits - Reduce bandwidth - Reduce latency - Reduce load on servers - Hide network failures 42
  42. 42. Caching Client Client
 Cache Proxy
 Cache Server Reverse
 Proxy
 Cache Client Client
 Cache Client Client
 Cache 43
  43. 43. HTTP Caching GET http://example.com/stuff ! < HTTP/1.1 200 OK < Cache-Control: max-age=60 Cache-Control: max-age=<delta-seconds>
 | s-max-age=<delta-seconds>
 | no-cache
 | no-store
 | … Read more Caching in HTTP 44
  44. 44. JAX-RS 2.0 Cache Control Directive Usage max-age cache.setMaxAge(int maxAge) s-max-age cache.setSMaxAge(int maxAge) no-cache cache.setNoCache(boolean noCache) no-store cache.setNoStore(boolean noStore) … … CacheControl cache = new CacheControl(); Read more javax.ws.rs.core.CacheControl 45
  45. 45. Caching and JAX-RS 2.0 @GET @Path("{id}") public Response read(@PathParam("id") int id) { Article article = articleDao.findById(id); CacheControl cacheControl = new CacheControl(); cacheControl.setMaxAge(60); ! return Response.ok(article) .cacheControl(cacheControl) .build(); } 46
  46. 46. Let's try curl -X GET "http://localhost:8081/rest/articles/8" -H "Accept: application/json" -v < HTTP/1.1 200 OK < Cache-Control: max-age=60 < Content-Type: application/json < { "id": 8, "title": "HTTP Caching and JAX-RS 2.0", "content": "JAX-RS 2.0 supports HTTP Caching" } 47
  47. 47. Wrapping Up JAX-RS 2.0 is a POJO-based HTTP-centric annotation-driven specification for for RESTful Web Services.
 Makes the developer focus on URLs, HTTP methods and Media Types. Implementations: - Apache CXF - Jersey - RESTeasy - Restlet - others 48
  48. 48. Q & A 49
  49. 49. Thank you! 50
  50. 50. Старший Разработчик Киноплатформы Дмитрий Чижиков dmytro.chyzhykov@yandex.ru ffbit

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