Introduction to OSGi, modularity & proof of concept in Apache Karaf with Hibernate persitsence

1. OSGi Experiments
Ladislav Gažo / gazo@seges.sk / @ladislavGazo

2. 2 | Internal use only
Restart container

3. 3 | Internal use only
Tomcat
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Pleeeenty of projects
=
Long time

4. 4 | Internal use only
Something was wrong
• start-up time long
• hot redeploy is fail
• restart takes long
• multiple wars? maybe
• JRebel? maybe
• one big bunch of bitter jars?
• YES – this needs a solution

5. 5 | Internal use only
OSGi
• old Alliance
• different class loading
– dependency hell no more
• modules a.k.a. bundles
• redeploy
• not clear what to choose
• but still small enough

6. 6 | Internal use only
Eclipse Equinox
Apache Felix
Oracle Glassfish
Eclipse Virgo
Apache Karaf

7. 7 | Internal use only
Challenges
• which runtime to choose
• how to properly structure
• inter/intra module
dependencies
• deployment model
• redeployment in dev
• database access
• Karaf
• Maven already helped a lot
• Blueprint, CDI
– optionally Spring, Guice
• e.g. from local m2 repo
• bundle:watch
• ehm... Hibernate is hard

8. 8 | Internal use only
Layers & Bundle & Lifecycle

9. 9 | Internal use only
Karaf PoC - https://github.com/lgazo/karaf-poc
fis-database fis-persistenceunitfis-database customer-domain event-domain
event-service
fis-shell fis-web
otherapp-persistenceunitotherapp-database order-domain
Features
• independent domain modules,
orchestrated persistence units
• multiple DBs
• service separated from view/access
modules
• multiple versions of a bundle

10. 10 | Internal use only
<packaging>bundle</packaging>
<plugin>
<groupId>org.apache.felix</groupId>
<artifactId>maven-bundle-plugin</artifactId>
<version>2.3.7</version>
<extensions>true</extensions>
<configuration>
<instructions>
<Bundle-SymbolicName>${project.artifactId}</Bundle-SymbolicName>
</instructions>
</configuration>
</plugin>

11. 11 | Internal use only
Interesting commands
• ./karaf debug
• bundle:watch
• log:tail
• bundle:list
• feature:repo-add + feature:install
• install -s wrap:mvn:postgresql/postgresql/9.1-901-1.jdbc4
• bundle:tree-show

12. 12 | Internal use only
Notable buzzwords + properties
• Blueprint
• Whiteboard
• Apache Aries, Eclipse
Gemini
• Distributed OSGi
• Pax
• SSH console, web console
• Features
• Language agnostic – bundles
can be in Java, Scala,
Groovy,...
• HttpService, Configuration
service, Activator, Logging

13. 13 | Internal use only
Thank you for your patience
gazo@seges.sk
@ladislavGazo

14. 14 | Internal use only
Links
• Karaf PoC - https://github.com/lgazo/karaf-poc
• Apache Karaf – http://karaf.apache.org
• Apache Aries - http://aries.apache.org/
• Hibernate OSGi - https://github.com/brmeyer/HibernateOSGi