RESTful Microservices In Java With Jersey Jakub Podlešák Software Engineer Oracle, Application Server Group September 29, 2014 Copyright © 2014, Oracle and/or its affiliates. All rights reserved.

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Copyright © 2014, Oracle and/or its affiliates. All rights reserved. Goal of The Presentation 5 To show how Jersey as JAX-RS 2.0 implementation could be used outside of a Java EE container in a light-weight fashion to implement RESTful micro- services in Java

Copyright © 2014, Oracle and/or its affiliates. All rights reserved. Program Agenda Microservices Primer JAX-RS/Jersey Primer Jersey features to support Microservices development

Copyright © 2014, Oracle and/or its affiliates. All rights reserved. Microservices Primer See this: 7

Copyright © 2014, Oracle and/or its affiliates. All rights reserved. Microservices primer Do not try to solve complex problems at once – I.e. avoid building a single monolithic application Break the big thing into several small parts You will end up with a number of small loosely coupled applications – That can work together 8

Copyright © 2014, Oracle and/or its affiliates. All rights reserved. Why to break it down? It is easier to design a small application that only does one thing Testing is easier … as well as deployment and maintenance Individual parts could evolve at different pace 9

Copyright © 2014, Oracle and/or its affiliates. All rights reserved. Desired properties of you microservices Small enough that it could fit into your head – Every application does only one thing (and does it well) Could be easily thrown away and re-written Clear boundaries – Remotely accessible uniform interface 10

Copyright © 2014, Oracle and/or its affiliates. All rights reserved. Application interface Be of the web not on the web! HTTP and universal media types can be consumed by different clients Looks familiar? You are right, this is REST 11

Copyright © 2014, Oracle and/or its affiliates. All rights reserved. Deployment Select whatever container fits you best Standalone “container-less” deployment often recommended – Single jar file/OS service vs. a WAR in an application server Container selection does not matter to application consumers – You have this uniform interface and clear boundaries, don’t you? – But you might also have some throughput requirements – Auto-scaling 12

Copyright © 2014, Oracle and/or its affiliates. All rights reserved. Microservices summary Many small apps Every app does only one thing (and does it well) REST interface Decoupled from each other and it’s clients Deployable/Testable/Scalable individually 13

Copyright © 2014, Oracle and/or its affiliates. All rights reserved. JAX-RS/Jersey primer JAX-RS 2.0 – part of Java EE 7 (2013) – defines a standard API for Implementing RESTful web services in Java REST client API Jersey 2 – provides production ready JAX-RS 2.0 reference implementation – brings several non-standard features 14

Copyright © 2014, Oracle and/or its affiliates. All rights reserved. Why JAX-RS/Jersey? REST is the natural way how to design Microservice interface JAX-RS provides widely adopted Java API for REST Jersey brings additional features that could help with other aspects – Lightweight container support (switch back to Java EE if needed) – Testing – Monitoring (Auto-scale) – Security – Redeploy – … 15

Copyright © 2014, Oracle and/or its affiliates. All rights reserved. Selected Jersey features Grizzly HTTP server support Test framework Application monitoring 16

Copyright © 2014, Oracle and/or its affiliates. All rights reserved. Grizzly HTTP server support URI AppURI = URI.create(" HttpServer httpServer = GrizzlyHttpServerFactory.createHttpServer( AppURI, new JaxRsApplication()); 17

Copyright © 2014, Oracle and/or its affiliates. All rights reserved. Grizzly HTTP server support – thread pool config HttpServer httpServer = GrizzlyHttpServerFactory.createHttpServer(AppURI, new JaxRsApplication(), false); NetworkListener grizzlyListener = httpServer.getListener("grizzly"); grizzlyListener.getTransport().setSelectorRunnersCount(4); grizzlyListener.getTransport().setWorkerThreadPoolConfig( ThreadPoolConfig.defaultConfig().setCorePoolSize(16).setMaxPoolSize(16)); httpServer.start(); 18

Copyright © 2014, Oracle and/or its affiliates. All rights reserved. Other supported containers Simple HTTP Server Jetty HTTP Container (Jetty Server Handler) Java SE HTTP Server (HttpHandler) Other containers could be plugged in via org.glassfish.jersey.server.spi.ContainerProvider SPI 19

Copyright © 2014, Oracle and/or its affiliates. All rights reserved. Jersey Test Framework Based on JUnit Support for TestNG available Multiple container support – Grizzly – In memory – Java SE Http Server – Jetty – External container support 20

Copyright © 2014, Oracle and/or its affiliates. All rights reserved. External Test Container You can test any (already running) REST application No need to have Jersey on the other side Use the following parameters: mvn test \ -Djersey.config.test.container.factory=org.glassfish.jersey.test.external.ExternalTestContainerFactory \ -Djersey.test.host=localhost -Djersey.config.test.container.port=

Copyright © 2014, Oracle and/or its affiliates. All rights reserved. Monitoring support Must be explicitly enabled – ServerProperties.MONITORING_STATISTICS_ENABLED – ServerProperties.MONITORING_STATISTICS_MBEANS_ENABLED – Register your own event listeners MonitoringStatistics could be injected into any resource and MonitoringStatistics stats; 22

Copyright © 2014, Oracle and/or its affiliates. All rights reserved. Summary When writing microservices in Java, JAX-RS is a natural choice to implement REST interface Jersey brings several non-standard options that might be handy: – Lightweight container support (switch back to Java EE container if needed) – Test framework – Monitoring features (auto-scaling) There is more to come in future Jersey versions 23

Copyright © 2014, Oracle and/or its affiliates. All rights reserved. Several Related sessions Client Orchestration and Reactive Programming in JAX-RS Applications [CON3408] Tuesday, Sep 30, 12:30 PM, Parc 55 – Mission Real-World RESTful Service Development Problems and Solutions [BOF2105] Monday, Sep 29, 7:00 PM, Moscone South 303 Securing JAX-RS Services With OAuth 2 [CON3774] Tuesday, Sep 30, 12:30 PM, Hilton Golden Gate 6/7/8 24

Copyright © 2014, Oracle and/or its affiliates. All rights reserved. THANK YOU!

Copyright © 2014, Oracle and/or its affiliates. All rights reserved. BACKUP JAX-RS/CDI demo on Grizzly HTTP server 26