OSGiOSGi
Yet another framework?Yet another framework?
Jiří Harazim
FI MU 2012
22. 11. 2012 Jiri HARAZIM: OSGi 2
AgendaAgenda
Introduction
Motivation
OSGi Framework
Demo
Conclusion
Discussion
22. 11. 2012 Jiri HARAZIM: OSGi 3
AgendaAgenda
Introduction
Motivation
OSGi Framework
Demo
Conclusion
Discussion
22. 11. 2012 Jiri HARAZIM: OSGi 4
IntroductionIntroduction
Survey: Who has never heard of OSGi?
OSGi = former Open Services Gateway initiative
Who are members of this initiative?
Adobe Systems, IBM, Oracle, Red Hat, Vmware,
Siemens AG, TIBCO, Hitachi, Mitsubischi Electric,
Telefonica S.A., Credit Suisse, Eclipse Foundation Inc.
and many others
22. 11. 2012 Jiri HARAZIM: OSGi 5
AgendaAgenda
Introduction
Motivation
OSGi Framework
Demo
Conclusion
Discussion
22. 11. 2012 Jiri HARAZIM: OSGi 6
Beyond Java ModularityBeyond Java Modularity
Java (1995) is cool, but:
Lacks modularity support (jar hell)
Hardly follows proved trends (dependency injection, services)
Is only a tool actually
Thus a bunch of proprietary solutions had emerged
(JBoss, NetBeans, servers and others)
Why? They address major pitfalls:
Different unit of assembly (NetBeans Modules)
Services support (Spring, Guice)
Runtime/environment support
22. 11. 2012 Jiri HARAZIM: OSGi 7
AgendaAgenda
Introduction
Motivation
OSGi Framework
Demo
Conclusion
Discussion
22. 11. 2012 Jiri HARAZIM: OSGi 8
OSGi FrameworkOSGi Framework
OSGi is a specification
Defines runtime environment called OSGi Framework
Examples: Apache Felix, Equinox, Knopflerfish
Runs on top of Java Virtual Machine
22. 11. 2012 Jiri HARAZIM: OSGi 9
ModulesModules
Bundle = unit of deployment, ordinary JAR file with
META-INF/MANIFEST.MF
Example of manifest file:
22. 11. 2012 Jiri HARAZIM: OSGi 10
Life-cycleLife-cycle
Each bundle deployed into framework has its own
lifecycle
Header Bundle-Activator acts as Main-Class
Lifecycle scheme:
22. 11. 2012 Jiri HARAZIM: OSGi 11
ServicesServices
Service = element of interaction between bundles
Binding is performed at runtime
In R4 and R5 specs much easier (Declarative Service)
22. 11. 2012 Jiri HARAZIM: OSGi 12
Services and DynamismServices and Dynamism
Handling dynamic services is difficult
They can apper or leave anytime
ServiceTracker was introduced to reduce the burden
Event-based approach with listeners
Much better but still a lot of effort required
IPOJO
Service-Oriented component framework, not specification
Tackles dynamism as non-functional aspect – much easier!
Predecessor of DS
Declarative Services
Service-Oriented component framework in R4.0 specification
22. 11. 2012 Jiri HARAZIM: OSGi 13
AgendaAgenda
Introduction
Motivation
OSGi Framework
Demo
Conclusion
Discussion
22. 11. 2012 Jiri HARAZIM: OSGi 14
DemoDemo
Let's have a look at two bundles:
Provider bundle – this one provides service into service registry
Client bundle – this one queries registry for the service and uses it
We use iPOJO to facilitate development
Annotations are translated to manifest-headers by bnd tool
We can also specify iPOJO components in XML
We launch example in Apache Felix Framework
Open Source, felix.apache.org
Provider Bundle Client Bundle
22. 11. 2012 Jiri HARAZIM: OSGi 15
AgendaAgenda
Introduction
Motivation
OSGi Framework
Demo
Conclusion
Discussion
22. 11. 2012 Jiri HARAZIM: OSGi 16
ConclusionConclusion
OSGi provides solid platform for developing pervasive
applications
Current release R5 introduces next benefits
Provide-Capability header
Replacement of OBR (Osgi Bundle Repository) rfc
Used heavily in a lot of projects
All of us know at least Eclipse and GlassFish
Good support of tools
Ant, Maven, Eclipse, WebConsole
22. 11. 2012 Jiri HARAZIM: OSGi 17
AgendaAgenda
Introduction
Motivation
OSGi Framework
Demo
Conclusion
Discussion
22. 11. 2012 Jiri HARAZIM: OSGi 18
DiscussionDiscussion
Questions? Suggestions? Opinions?
22. 11. 2012 Jiri HARAZIM: OSGi 19
The EndThe End
Thank you for your attention!