Microservice avec les micro-frameworks Java @ DevoxxFR 2016

Hands-on DEVOXX FR 2016.
Feign, SparkJava, Micro frameworks, Microservices

Transcript

1. #DevoxxFR 20/04/2016 #feign #sparkjava 3 heures pour développer un micro-service avec les micro-frameworks Java
2. #DevoxxFR Laurent Baresse Developer & Geek lbaresse@ekito.fr @Baresse Igor Laborie Expert Web & Java igor@monkeypatch.io @ilaborie #feign #sparkjava
3. #DevoxxFR Roadmap 13:30 - Introduction to micro-XXX MyCellar 13:45 - Feign Exercises Set #1 15:00 - Coffee Time 15:15 - SparkJava Exercises Set #2 16:30 - End #feign #sparkjava
4. #DevoxxFR Practical notes Wifi SSID devoxxfr-hol / hol@1375 Requirement: JDK 8, Maven 3, your favorite IDE Download projects - https://ilaborie.org/DevoxxFR/ Or clone github project - https://github.com/Baresse/FeignSparkJava-exos #feign #sparkjava
5. #DevoxxFR Introduction to micro-XXX #feign #sparkjava
6. #DevoxxFR Microservices #feign #sparkjava Martin Fowler : Microservices (http://martinfowler. com/articles/microservices.html) • Componentization via Services • Decentralized governance • Decentralized data management
7. #DevoxxFR Micro-frameworks #feign #sparkjava • Plenty of micro-framework availables • Criteria ◦ Simple and mastered in few hours ◦ Community ◦ Elegant & Java 8 oriented
8. #DevoxxFR MyCellar #feign #sparkjava
9. #DevoxxFR #feign #sparkjava
10. #DevoxxFR Cellar Service microservices: mockup services (authentication, reference, comment and stock) src/main/java // devoxx.microframeworks.exos • models: Pojo used in the application • routes: Cellar service REST routes implementation (Spark Java) • services: REST clients services implementation (Feign) • Main: Cellar service Main class (embed cellar front-end) #feign #sparkjava
11. #DevoxxFR Start others microservices Open 4 terminals / consoles ./start-authentication-services.sh ./start-reference-services.sh ./start-comments-services.sh ./start-stocks-services.sh #feign #sparkjava $ ./start-authentication-service.sh [Thread-0] [INFO] log - Logging initialized @363ms [Thread-0] [INFO] JettySparkServer - == Spark has ignited ... [Thread-0] [INFO] JettySparkServer - >> Listening on 0.0.0.0:8093 [Thread-0] [INFO] Server - jetty-9.3.z-SNAPSHOT [Thread-0] [INFO] ServerConnector - Started ServerConnector@50f244a7{HTTP/1.1, [http/1.1]}{0.0.0.0:8093} [Thread-0] [INFO] Server - Started @450ms
12. #DevoxxFR Or if you <3 Docker $ docker-compose up Creating sparkfeign-auth Creating sparkfeign-reference Creating sparkfeign-stocks Creating sparkfeign-comments Attaching to sparkfeign-auth, sparkfeign-reference, sparkfeign-stocks, sparkfeign-comments sparkfeign-auth | [Thread-0] [INFO] log - Logging initialized @578ms sparkfeign-reference | [main] [INFO] WineDao - Parse wines database :323 wines read. sparkfeign-auth | [Thread-0] [INFO] JettySparkServer - == Spark has ignited ... sparkfeign-reference | [Thread-0] [INFO] log - Logging initialized @565ms sparkfeign-auth | [Thread-0] [INFO] JettySparkServer - >> Listening on 0.0.0.0: 8093 ...
13. #DevoxxFR Feign Consuming RESTful WebService #feign #sparkjava
14. #DevoxxFR Why Feign ? #feign #sparkjava
15. #DevoxxFR com.netflix.feign:feign-core:8.16.0 * for feign-core, others extensions had few https://github.com/Netflix/feign Apache License v2.0 Java 7+, Java 8 friendly No dependencies* #feign #sparkjava
16. #DevoxxFR Interface & Annotations [1/5] public interface CatClient { List<Cat> findAll(); Cat findById(String id); Cat create(Cat cat); // ... } #feign #sparkjava
17. #DevoxxFR Interface & Annotations [2/5] public interface CatClient { @RequestLine("GET /cats") List<Cat> findAll(); Cat findById(String id); Cat create(Cat cat); // ... } #feign #sparkjava
18. #DevoxxFR Interface & Annotations [3/5] public interface CatClient { @RequestLine("GET /cats") List<Cat> findAll(); @RequestLine("GET /cats/{id}") Cat findById(@Param("id") String id); Cat create(Cat cat); // ... } #feign #sparkjava
19. #DevoxxFR Interface & Annotations [4/5] public interface CatClient { @RequestLine("GET /cats") List<Cat> findAll(); @RequestLine("GET /cats/{id}") Cat findById(@Param("id") String id); @RequestLine("POST /cats") Cat create(Cat cat); // ... } #feign #sparkjava
20. #DevoxxFR Interface & Annotations [5/5] @Headers("Accept: application/json") public interface CatClient { @RequestLine("GET /cats") List<Cat> findAll(); @RequestLine("GET /cats/{id}") Cat findById(@Param("id") String id); @Headers("Content-Type: application/json") @RequestLine("POST /cats") Cat create(Cat cat); // ... } #feign #sparkjava
21. #DevoxxFR Build the instance public static CatClient create(String url) { return Feign.builder() // extra configuration ... .target(CatClient.class, url); } Use the Feign.Builder() #feign #sparkjava
22. #DevoxxFR Body Encoder & decoder It’s easy to create custom encoder/decoder. public static CatClient create(String url) { return Feign.builder() .encoder(new GsonEncoder()) .decoder(new GsonDecoder()) .target(CatClient.class, url); } Available extensions: GSON, Jackson, JAXB, Sax #feign #sparkjava
23. #DevoxxFR Error Decoder public static CatClient create(String url) { return Feign.builder() .errorDecoder((msg, response) -> new WTFException(response.status())) .target(CatClient.class, url); } Feign throw a FeignException on NOK response #feign #sparkjava
24. #DevoxxFR RequestInterceptor customisation RequestInterceptor ~ Consumer<RequestTemplate> Example: add an HTTP header public static CatClient create(String url) { // TODO get user JSON Web Tokens String jwt = ""; return Feign.builder() .requestInterceptor(template -> { template.header("Authorization", "Bearer " + jwt)); }).target(CatClient.class, url); } #feign #sparkjava
25. #DevoxxFR Others extensions ... Implement Contract for custom annotations (e.g. JAX-RS) Use another HTTP client implements Client Apache HttpClient: feign-httpclient OkHttp: feign-okhttp Also have integration for SLF4J logging: feign-slf4j Ribbon: feign-ribbon Histryx circuit breaker: feign-histryx ... #feign #sparkjava
26. #DevoxxFR Exercises Set #1 #feign #sparkjava
27. #DevoxxFR #feign #sparkjava
28. #DevoxxFR Ex 1.1 : Encoder/Decoder JSON Ex 1.2: ReferenceService Ex 1.3: CommentService Ex 1.4: StockService Ex 1.5 (bonus): Jackson instead of Gson Ex 1.6 (bonus): Add logs Ex 1.7 (bonus): connect Heroku -- PAUSE -- #feign #sparkjava
29. #DevoxxFR SparkJava #feign #sparkjava
30. #DevoxxFR Why Spark Java ? #feign #sparkjava
31. #DevoxxFR TL;TR: The promise... <dependency> <groupId>com.sparkjava</groupId> <artifactId>spark-core</artifactId> <version>2.3</version> </dependency> #feign #sparkjava http://localhost:4567/hello import static spark.Spark.*; public class HelloWorld { public static void main(String[] args) { get("/hello", (req, res) -> "Hello World"); } }
32. #DevoxxFR Spark Java http://sparkjava.com Apache License v2.0 Lightweight and embedded web server (Jetty) #feign #sparkjava
33. #DevoxxFR Roadmap Embedded Server Configuration Routes Request Response Filters Exceptions #feign #sparkjava
34. #DevoxxFR Embedded web server - Configuration // If provided port = 0, an arbitrary available port will // be used ; default 4567 port(int port) // the folder in classpath staticFileLocation(String folder) // the external folder serving static files externalStaticFileLocation(String externalFolder) Configuration before any route / filter mapping #feign #sparkjava
35. #DevoxxFR Routes #feign #sparkjava Routes are matched in the order they are defined. The first route that matches the request is invoked. • Verb: get, post, put, delete, head, trace, connect, options • Path: "/path", "/path/:param" • Callback: (request, response) -> { } Optionally: • Accept-type = "application/json" • ResponseTranformer
36. #DevoxxFR Routes matching // Show something get("/", (request, response) -> { ... }); // Create something post("/", (request, response) -> { ... }); // Update something put("/", (request, response) -> { ... }); // Annihilate something delete("/", (request, response) -> { ... }); // Appease something options("/", (request, response) -> { ... }); #feign #sparkjava
37. #DevoxxFR Routes matching & URL parameters // matches "GET /hello/foo" and "GET /hello/bar" // request.params("name") is 'foo' or 'bar' get("/hello/:name", (request, response) -> { return "Hello: " + request.params("name"); }); NOTE : Query parameters are not used for URL matching #feign #sparkjava
38. #DevoxxFR Request request.body(); // request body sent by the client request.bodyAsBytes(); // request body as bytes request.headers(); // the HTTP header list request.headers("BAR"); // value of BAR header request.params("foo"); // value of foo path parameter request.params(); // map with all parameters request.queryParams(); // the query param list request.queryParams("FOO"); // value of FOO query param request.queryParamsValues("FOO") // all values of FOO query param See Spark.Request for other methods and details #feign #sparkjava
39. #DevoxxFR Response response.body("Hello"); // sets content to Hello response.header("FOO", "bar"); // sets header FOO with value bar response.redirect("/example"); // browser redirect (HTTP 302) response.redirect("/bar", 301); // moved permanently response.status(401); // set status code to 401 response.type("text/xml"); // set content type to text/xml See Spark.Response for other methods and details #feign #sparkjava
40. #DevoxxFR Filters before((request, response) -> { // ... check if authenticated halt(401, "You are not welcome here"); }); before("/protected/*", (request, response) -> { // ... check if authenticated halt(401, "Go Away!"); }); after((request, response) -> { response.header("foo", "set by after f ilter"); }); Filters can: read the request read/modify the response #feign #sparkjava
41. #DevoxxFR Exceptions // Should an exception be thrown somewhere... get("/throwexception", (request, response) -> { throw new NotFoundException(); }); // Exception handler exception(NotFoundException.class, (e, request, response) -> { response.status(404); response.body("Resource not found"); }); #feign #sparkjava
42. #DevoxxFR With Spark Java, you can also ... • Cookies • Session • WebSockets (only with embedded web server) • Request/Response GZIP • View and Templatings (mustache, thymeleaf, velocity, …) #feign #sparkjava
43. #DevoxxFR Exercises Set #2 #feign #sparkjava
44. #DevoxxFR #feign #sparkjava
45. #DevoxxFR Ex 2.1 : WineRoute Ex 2.2: CellarRoute Ex 2.3: CommentRoute Ex 2.4: Exception handlers Ex 2.5 (bonus): Asynchronous services aggregation Ex 2.6 (bonus): Docker #feign #sparkjava
46. #DevoxxFR Resources Feign : https://github.com/Netflix/feign SparkJava: http://sparkjava.com Github (Exos) https://github.com/Baresse/FeignSparkJava-exos Github (Microservices-Mocks) https://github.com/Baresse/FeignSparkJava-mocks #feign #sparkjava
47. #DevoxxFR Q / A Thanks ! #feign #sparkjava