OSGi & Java EE: A hybrid approach to Enterprise Java Application Development, Sahoo

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There's a considerable activity in the enterprise Java community about the use of OSGi in Java EE applications. We call such applications "hybrid applications." With hybrid applications, developers can continue to build standard and familiar enterprise application components, such as Java Servlets and EJBs, and take full advantage of:

* Features such as modularity/dependency management, service dynamism, and more provided by OSGi
* Infrastructure services such as transaction management, security, persistence, and more offered by Java EE

This session will present the current state of affairs, discuss the benefits of hybrid applications, and demonstrate development and deployment of such applications.
GlassFish will be used for demonstration.

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OSGi & Java EE: A hybrid approach to Enterprise Java Application Development, Sahoo

  1. 1. 1 <Insert Picture Here> OSGi and Java EE: A Hybrid Approach to Enterprise Java Application Development Sanjeeb Sahoo Staff Engineer, Sun Microsystems India Pvt. Ltd.
  2. 2. 2 The following is intended to outline our general product direction. It is intended for information purposes only, and may not be incorporated into any contract. It is not a commitment to deliver any material, code, or functionality, and should not be relied upon in making purchasing decisions. The development, release, and timing of any features or functionality described for Oracle’s products remains at the sole discretion of Oracle. Safe Harbor Statements
  3. 3. 3 The preceding is intended to outline our general product direction. It is intended for information purposes only, and may not be incorporated into any contract. It is not a commitment to deliver any material, code, or functionality, and should not be relied upon in making purchasing decisions. The development, release, and timing of any features or functionality described for Oracle’s products remains at the sole discretion of Oracle.
  4. 4. 4 <Insert Picture Here> Agenda • OSGi 101 • OSGi meets Java EE – Hybrid Applications • Advanced usecases • Hybrid Application Demo • Q & A
  5. 5. 5 <Insert Picture Here> Agenda • OSGi 101 • OSGi meets Java EE – Hybrid Applications • Advanced usecases • Hybrid Application Demo • Q & A
  6. 6. 6 OSGi Service oriented dynamic module system for Java
  7. 7. 7 OSGi Layers
  8. 8. 8 Module Layer • Bundle – a unit of modularity in OSGi • Encapsulation • Lifecycle independent of the JVM • Versionable • Packaged as a JAR (classes + Manifest with OSGi metadata) • Very explicit dependency specification • Well defined dependency resolution rules
  9. 9. 9 Bundle-SymbolicName: com.acme.hello.startup Bundle-Name: Hello World OSGi Sample Bundle-Version: 1.0.1 Bundle-ManifestVersion: 2 Bundle-Activator: com.acme.hello.startup.MyActivator Export-Package: com.acme.hello.startup;version=1.0.0 Import-Package: org.osgi.framework;version=1.3 OSGi Metadata
  10. 10. 10 Classloading in OSGi Image from the OSGi R4 Core Specification
  11. 11. 11 Lifecycle Layer • Provides an API to manage bundles – BundleContext.install – BundleContext.uninstall – Bundle.update • BundleActivator • BundleListener – listen to BundleEvents – Synchronous – Asynchronous
  12. 12. 12 Bundle Lifecycle Image from the OSGi R4 Core Specification
  13. 13. 13 Service Layer • In-VM SOA • Service Registry – Register – Unregister • Service is a POJO • Service Dynamism – Service tracking • Service Discovery – LDAP filter based queries
  14. 14. 14 Interactions between OSGi Layers Image from the OSGi R4 Core Specification
  15. 15. 15 OSGi benefits – a recap • Layered approach • Modularity – Enforces modularity – Ensures class-space consistency – Enables component reuse – Supports versioning and evolution • Dynamism – Bundles – Services • Ease of deployment and management – OBR • Bundle deployment order is not relevant – Faster deployment cycle
  16. 16. 16 OSGi meets Java EE
  17. 17. 17 <Insert Picture Here> Agenda • OSGi 101 • OSGi meets Java EE – Hybrid Applications • Advanced usecases • Hybrid Application Demo • Q & A
  18. 18. 18 Java EE Platform of choice for enterprise applications • Widely used APIs (JPA, JTA, JAXB, JNDI) • Component Models (Servlet, EJB, JAX-RS) • Frameworks (JSF, CDI) • Ease of Use (Annotations, Convention over Configuration) • Platform provided infrastructure services (Transaction, Security, Persistence, Remoting) • Tools (IDE, Management, Monitoring) • Ubiquitous deployment platform for enterprise applications
  19. 19. 19 Hybrid Applications Meeting of the two worlds • OSGi + Java EE = Hybrid application • Hybrid application – An OSGi bundle – And a Java EE Archive • Leverage the capabilities of both the platforms – Enterprise applications can now • be built as modular OSGi bundles • use OBR, Config Admin, service tracking, etc. – OSGi bundles can now use Java EE services like JTA, JPA, etc.
  20. 20. 20 Current State • OSGi Enterprise Expert Group (EEG) – Relased OSGi Service Platform Enterprise Specification 4.2 in 2010 • Open source efforts – Project GlassFish – Project Aries – Eclipse Gemini
  21. 21. 21 OSGi/Web Application (WAB) • Web Application Bundle (WAB) – WAR + OSGi metadata + Web-ContextPath header • Can use all enterprise APIs (like JPA, JTA) • Wrapped WAR support – webbundle: URL scheme
  22. 22. 22 Bundle-SymbolicName: com.acme.hellowab Bundle-Name: Hello World OSGi Web Application Bundle-Version: 1.0.0 Bundle-ManifestVersion: 2 Bundle-Activator: com.acme.hellowab.MyActivator Import-Package: javax.servlet; javax.servlet.http; version=3.0, org.osgi.framework; version=1.5 Bundle-ClassPath: WEB-INF/classes, WEB-INF/lib/foo.jar Web-ContextPath: /hello OSGi Metadata of a WAB
  23. 23. 23 Hybrid application bundle lifecycle
  24. 24. 24 Enterprise OSGi Specifications • OSGi/Web Application • OSGi/JPA • OSGi/JDBC • OSGi/JTA • OSGi/JNDI • OSGi/HTTP Service • OSGi Blueprint Service
  25. 25. 25 EE APIs in OSGi • OSGi/JDBC – JDBC driver as DataSourceFactory – Dynamic discovery of driver details – Multiple versions of same driver • OSGi/JTA – JTA artifacts available as OSGi Services • OSGi/JPA – Enhancement of JPA entities at runtime – Same packaging rules as JPA and also deploy entities as a bundle – Shared Persistence Unit and thereby shared second level cache
  26. 26. 26 Tools • BND (http://www.aqute.biz/Code/Bnd) – de-facto tool for OSGi metadata generation – maven-bundle-plugin – Ant task • IDE – Eclipse – NetBeans – IntelliJ IDEA
  27. 27. 27 Advanced Usecases
  28. 28. 28 <Insert Picture Here> Agenda • OSGi 101 • OSGi meets Java EE – Hybrid Applications • Advanced usecases • Hybrid Application Demo • Q & A
  29. 29. 29 OSGi/EJB Application • Allows you to develop managed, transactional, secure OSGi services with very little knowledge of OSGi • Make your existing EJB service available to OSGi clients with little effort • Achieved through simple manifest metadata – Export-EJB: ALL/None/<names of stateless local EJB>
  30. 30. 30 Bundle-SymbolicName: com.acme.helloEjbOsgi Bundle-Name: Hello World OSGi EJB Bundle Bundle-Version: 1.0.0 Bundle-ManifestVersion: 2 Import-Package: javax.ejb; version=3.0, Export-EJB: ALL OSGi Metadata of an OSGi/EJB bundle
  31. 31. 31 CDI • Brings type-safe dependency injection to EE platform – Strong typing and loose coupling • Well defined life cycle of stateful objects bound to life cycle contexts • Ability to decorate and intercept injected Beans • An event notification model • An ability to develop portable extensions that integrates with the container to extend the runtime
  32. 32. 32 GlassFish CDI/OSGi Portable Extension • Use of CDI for type safe injection of OSGi services @WebServlet(urlPatterns = “/login”) public class FooServlet implements HttpServlet {     @Inject      @org.glassfish.osgicdi.OSGiService(           dynamic=”true”,            timeout = 200,            serviceCriteria=<an ldap query >)     FooService foo; }
  33. 33. 33 Demo: Putting them together
  34. 34. 34 Demo schematic • WAB • JPA- LAZY loading • EJB as Service • OSGi Service Injection • OBR • Security/Transaction Context propagation Simple OSGi Bundle OSGi Service Simple OSGi Service EJB OSGi Service Advanced WAB Simple WAB
  35. 35. 35 Call To Action • Want to build hybrid applications? – Try our tutorial at http://tinyurl.com/osgieehol • Want to try out? – Use GlassFish 3.1 trunk builds from http://glassfish.org • Questions? – users@glassfish.dev.java.net
  36. 36. 36 References • OSGi Service Platform Core and Enterprise Specification 4.2 – http://www.osgi.org • Project GlassFish – http://glassfish.org • Hybrid application samples – http://wikis.sun.com/display/GlassFish/BlogsGfOsgi
  37. 37. 37 <Insert Picture Here> Agenda • OSGi 101 • OSGi meets Java EE – Hybrid Applications • Advanced usecases • Hybrid Application Demo • Q & A
  38. 38. 38 <Insert Picture Here> OSGi and Java EE: A Hybrid Approach to Enterprise Java Application Development Sanjeeb Sahoo Staff Engineer, Sun Microsystems India Pvt. Ltd.

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