A presentation about how to create and combine Java EE and OSGi (aka hybrid application). Presentation held at Devcon12 2012 (Sweden, Karlskrona)

1. ANDREAS ENBOHM (@enbohm)
2012-09-13
HYBRID APPLICATIONS
- Combining the Power of Java EE and OSGi

2. About Me

3. Agenda
 Introduction
 Java EE
 OSGi + Java EE
 Demo
- Java EE + OSGi
- Glassfish V3
 Future<?>

4. Why This Presenation?
Homer Simpson Programming Model:
”Let some else do it!”

5. Java EE

7. Java EE
”The industri standard for enterprise computing. JEE is
used for mission-critical, large-scale, multi-tiered,
scalable, reliable, and secure applications”

8. Java EE
 A set of API
- JTA, JPA, JSF, EJB, JMS, JCA, Servlet, CDI, JAX-WS, JAX-RS…
 Application Servers
- Oracle AS, IBM Websphere, Apache Geronimo, JBoss, Glassfish, JOnAS,
TomEE, Resin…
 Used within
- Finance
- Telecom
- Manufacturing
- …

9. Ewok* EJB Appreciation
*Ewoks from motion picture ”Star Wars Return of the Jedi”

10. ”EJB/J2EE IS HEAVYWEIGHT”

11. ”EJB/J2EE IS HEAVYWEIGHT”
 EJB != heavyweight
- acctually its considered ultra-lean
- please tell if anyone know any other tech!
 One jar file (java-ee-6.jar, 967 kB)
 One single annotation
- @Stateless
 Glassfish (55/200MB)
- restart in ~3 seconds
- hot deployment
- full OSGi support

12. Why Java EE
 Hyper productive
- time-to-market
 Maximize focus on Business functionality
- Inversion of control (DI)
- Decorators
- Aspects
- Schedulers
- Events
- Asyncronous calls
- …
 Helps you with a lot of non-functional requirements

13. Why Java EE
 Thread-safe
- every thread gets it own bean instance
 Transaction management
- transaction are automatically started, commited or rollbacked
 Pooling of Session beans
- prevent DDOS attacks
- scale up/down
 Distributed components
- runs in a multi-tier architecture
- failover, scalability

14. Why Java EE
 Deployment
- very few (if any) xzy.xml deployment desc.
- runs on several app servers and/or clouds
 Elastic

15. Why Java EE
 Ultra-lean
- what more can be removed?

16. EJB Component
public interface PaymentService {
public ProductReceipt pay(int productId);
}
@Stateless
public class PaymentEJB implements PaymentService {
public ProductReceipt pay(int productId){
//implementation goes here
}
}
EJB-annotation (convention over configuration)
Plain interface (not
required)

17. TDD and Java EE
 Unit test
- POJO
 Integration test
- embedded container
- arquillian
- pax exam

18. TDD and Java EE
EJBContainer container = EJBContainer.createEJBContainer();
Context ctx = container.getContext();
PaymentService service = (PaymentService) ctx
.lookup("java:global/classes/PaymentEJB");
Assert.assertNotNull(service);

19. Areas Not Covered by Java EE
 Java lacks (real) modularity
- known problem since day 1
- many app servers builds on OSGi
- may change when Project Jigsaw is release (2013)
 Service tracking
 Criteria-based service selection
 ”Jar-hell”
- NoSuchMethodException
- Classpath / Dependencies

20. Areas Not Covered by Java EE
 Well defined life-cycle of components
 Multiple instances of a service/component
 Hot-swapping* of components
* debug mode doesn’t count

21. Hello OSGi!
“OSGi technology provides a service-oriented,
component-based environment for developers and
offers standardized ways to manage the software
lifecycle.” - Wikipedia

22. Hello OSGi!
Simply put, a modularity layer for the Java platform

23. Why OSGi
 Separation of concerns (i.e modularization)
 Key concepts
- Cohesion
- Coupling
 Containers
- Apache Felix
- Knopflerfish
- Equinox

24. Why OSGi
 But how about OO in Java?
- OO is all about high cohesion and low coupling, right?
 Java has a limited modularization
- no transitive dependencies
- public (keyword) is ’too public’
- error prone class path
- low-level modularization (packages)

25. OSGi Layers
 OSGi Layered Architecture
 Module
- packaging and sharing
of code
 Life Cycle
- module management
 Service
- interaction between
modules

26. OSGi Module Layer
 Bundle
–a unit of modularity in OSGi
 Package as a JAR (classes + MANIFEST.MF with OSGi metadata)
 Versionable
 Clear dependency declaration
 Clear dependency resolution rules

27. OSGi Metadata
 Manifest.MF
Manifest-Version: 1.0
Built-By: aenbohm
Bundle-ManifestVersion: 2
Bundle-Name: hybridCommon
Bundle-SymbolicName: hybridCommon
Bundle-Version: 1.0.0
Export-Package: com.acme.hybrid.devcon.entity;version="1.0.0"
Import-Package: javax.persistence,javax.xml.bind.annotation

28. OSGi Life Cycle Layer
 Life Cycle

29. OSGi Service Layer
 Services registry
- register
- unregister
 Service is a POJI
- focus on the contract/interface
- reduce coupling
 Service discovery
- LDAP filter based queries

30. Best of Both Worlds
 How about combining JEE & OSGi?
- productivity
- reusable bundles with visible dependencies
- version control of components
- automatic transaction handling
- ..

31. Hello Hybrid Application!
31
© 2012 Capgemini. All rights reserved.

32. Hybrid Applications
“a hybrid application bundle is an OSGi bundle as well
as a Java EE module. At
runtime, it has both an OSGi bundle context and a Java
EE context.”

33. Hybrid Applications
 Allows you to develop managed, transactional OSGi services with little
knowledge of OSGi
 Makes your EJB:s available as OSGi services with little effort
- bundles can use Java EE services like JTA, JPA, etc
 Supports Stateless and Singleton EJBs

34. Hybrid Applications
How to turn your Java
EE artifacts to OSGi
Services?

35. Hybrid Applications
…
Implementation-Title: hybrid
Implementation-Version: 1.3
Bundle-ClassPath: WEB-INF/classes/
Bundle-Name: hybrid
Bundle-SymbolicName: com.acme.hybrid.service.impl
Bundle-Version: 1.3.0
Export-EJB: ALL
Web-ContextPath: /hybrid
…
Manifest.MF
WAB (web application bundle); OSGi Spec. 4.2

36. Hybrid Applications
 EJB artifacts + Manifest.MF = ’Declarative’ Service
- Enterprise Application Bundle (EAB)
- Web Application Bundle (WAB)
 ExportEJB: List of EJBs to be exported as OSGi services.
- Values: NONE, ALL or fully qualified name

37. Hybrid Applications
 In VM SOA
- service-oriented design
- domain-driven design
 Different support for hybrid apps
- JBoss
- Glassfish
- IBM Websphere
- Geronimo
 This makes hybrid apps less portable!
- RFP 152 ”EJB Integration”
- RFP 146 ”OSGi/CDI Integration”

38. Glassfish + OSGi
 OSGi R4, version 4.2 compliant
- Uses Apache Felix as OSGi runtime
 Jave EE / OSGi services in Glassfish
- JTA
- JPA
- JMS
- HTTP Service
- Event Admin
- Config Admin
- …

39. Glassfish + OSGi
 Type safe injection with CDI Extension
ServiceTracker tracker =
new ServiceTracker(context, Hello.class.getName(), null);
tracker.open();
Hello hello = (Hello) tracker.getService();
System.out.println(hello.sayHello("Duke"));
@Inject @OSGiService(dynamic=true)
Hello hello;
System.out.println(hello.sayHello("Duke"));
With CDI annotation:

40. PROVE IT ! (Demo time)
 Asyncronous invocations
 Events
 Decorators
 Service update (hot deployment)
 REST service

41. Demo Overview
HybridCommon
(standard OSGi bundle containing
domain objects)
HybridClient
(WAB exposes a service via Jax-RS)
HybridBackend
(EJB as OSGi service, EAB)
<uses>
<uses>
OSGi Service
Registry
<publish>
<discover>

42. CONS JEE + OSGi
 ”With great power comes great complexity”
- combining OSGi + JEE
- two different component models
- developers need to know both models
- not all app server have (full) hybrid support
- different containers with different characteristics
 Technology overlap of Java EE and OSGi
- events, security, monitoring…
 Declarative Services, iPojo, Blueprint, ServiceTracker…

43. FUTURE<JavaEE&OSGi>
Project Jigsaw

44. FUTURE<JavaEE&OSGi>
 Project Jigsaw
- monolitic JVM
- will address both compile & runtime (Maven + OSGi)
- no service register nor life cycle handling
- (probably) not until Java 9

45. FUTURE<JavaEE&OSGi>
OSGi + Maven?

46. FUTURE<JavaEE&OSGi>
 OSGi
- CDI integration
- EJB incorporation
- more app servers will support hybrid
apps
 Jigsaw and OSGi will definitely co-exist
- Project Penrose

47. SUMMARY
 Features in Java EE and OSGi
- productivity and modularity
 How to combine them
- WAB/EAB
 Demonstrated a hybrid application
- using Glassfish + Apache Felix

48. | Sector, Alliance, Offering
USEFUL LINKS
www.osgi.org
www.glassfish.org
http://www.oracle.com/technetwork/java/javaee/overvie
w/index.html
http://www.jboss.org/arquillian.html
http://mreinhold.org/blog/late-for-the-train-qa

49. Q & A
49
© 2012 Capgemini. All rights reserved.
http://www.slideshare.net/enbohm
Twitter: @enbohm

50. www.se.capgemini.com
The informationcontained in this presentation is proprietary. ©2012 Capgemini. All rights reserved