Short introduction to OSGi for Java developers.

1. OSGi
as Enterprise Integration Platform
Elek Márton
@anzix
2014 September
DPC Consulting

2. Agenda
Typical question:
JavaEE or Spring based application?
Our question:
Is the OSGi good enough for a third way?
● What is OSGi
– Classpath separation
– Service definitions
– Lifecycle
● How does an OSGi application server looks like?
– Felix, Karaf, ServiceMix
– JBoss Fuse, Fabric8.io

3. OSGi

4. What is OSGi
● Modular system and service platform for Java
– Specification (similar to J2EE)
– Ecosystem (eg. exams are announced at 2014.09)
● Jigsaw vs. OSGi interoperability ????
– (PoC: project penrose)
OSGi R1 2000.05
OSGi R2 2001.10
OSGi R3 2003.03
OSGi R4 2005.10
OSGi R4.1,4.2,4.3 2009.09-2011.04
OSGi R5 2012.06
J2EE 1.2 1999.12
J2EE 1.3 2001.09
J2EE 1.4 2003.11
JavaEE 5 2006.05
JavaEE 6 2009.12
JavaEE 7 2013.06

5. ● OSGi runtime is collection of bundles
● Bundle:
– Plain old jar file
– With plain old META-INF/MANIFEST.MF
● With OSGi specific entries in the manifes
OSGi bundle

6. Classpath separation
● Package based
● Bundles explicitly
imports and exports packages
– META-INF/MANIFEST.MF
Bundle1
Export-Package: hu.dpc.helloworld
;version="1.0.0"
Bundle2
Import-Package: hu.dpc.helloworld
;version="1.0.0"

7. Lifecycle management
● Every bundle has a lifecycle.
● Activator in
META-INF/MANIFEST.MF
Bundle-Name: Hello World
Bundle-SymbolicName: hu.dpc.helloworld
Bundle-Activator: hu.dpc.Activator

8. Service definition
● API to publish/use implementation for a specific
interface
– With optional metadata set
● Programmatic API: there are extensions to use
declarative approach
– blueprint
– DS (declarative services
● Main set of useful interfaces
– Logging, Config Admin, Http, ...

9. Runtime container

10. Apach Felix
OSGi container

11. Apache Karaf
Apach Felix
OSGi container
Hibernate
Spring
CXF
● Hot deployment
● Dynamic configuration
○ (etc/*.properties -> OSGi config API)
● Provisioning (feature definition)
● KAR archive
● More advanced shell
● Instance management
○ Parent container/Child container
○ The binaries are shared

12. Apache Karaf
Apach Felix
OSGi container
Apache ServiceMix
Hibernate
Spring
CXF
Camel ServiceMix
● Hot deployment
● Dynamic configuration
○ (etc/*.properties -> OSGi config API)
● Provisioning (feature definition)
● KAR archive
● More advanced shell
● Instance management
○ Parent container/Child container
○ The binaries are shared

13. Apache Karaf
Apach Felix
OSGi container
Apache ServiceMix
JBoss Fuse
● Clustering / auto provisioning
● Microservice management
Hibernate
Spring
CXF
Fabric
Camel ServiceMix
● Hot deployment
● Dynamic configuration
○ (etc/*.properties -> OSGi config API)
● Provisioning (feature definition)
● KAR archive
● More advanced shell
● Instance management
○ Parent container/Child container
○ The binaries are shared

14. Apache Karaf
Apach Felix
OSGi container
Apache ServiceMix
JBoss Fuse / FABRIC8.IO
● Clustering / auto provisioning
● Microservice management
Hibernate
Spring
CXF
Fabric
Camel ServiceMix
● Hot deployment
● Dynamic configuration
○ (etc/*.properties -> OSGi config API)
● Provisioning (feature definition)
● KAR archive
● More advanced shell
● Instance management
○ Parent container/Child container
○ The binaries are shared

15. Summary
● Third way with own strength and weakness
● Strength
– Modularity, Modularity, Modularity
● Classloader separation
● Lifecycle management
● Service producer/consumer pattern
– Well defined standard service APIs
– More control to fine tune the integration
● Weakness
– Additional complexity even if the classloader separation
and the lifecycle management is not needed
– Many different project should be used together
– DIY environment, everything is possible, but more
knowledge needed about the platform.

16. Q&A