The OSGi Framework Multiplication
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This document discusses launching multiple OSGi frameworks within a single Java Virtual Machine (JVM). It describes challenges like runtime isolation, application models, and avoiding conflicts between frameworks and applications. The RFC 0138 proposes addressing these issues by allowing child frameworks to be created and managed, and by multiplexing singleton services like URL handlers across frameworks. However, the specification is incomplete and complex to implement. The document concludes that running multiple frameworks in a single JVM is important but not straightforward to achieve.
![Why ? – Application Model
composite {
Creation of composite
Install-Bundle:
Deployment packages++ foo; bundle-version=[1.0.0,1.2.0),
bar; bundle-version=[1.0.0,1.0.0]
Allows to describes Import-Package: waz; version=2.0.0
applications Export-Package: baz; version=1.0.1
}
Exemple
Such composites should
be ran in an isolated child
framework
Child framework
OSGi™ framework
Java Virtual Machine
6 The Framework Multiplication](https://image.slidesharecdn.com/ougf-theframeworkmultiplication-orig-091021093629-phpapp01/85/The-OSGi-Framework-Multiplication-6-320.jpg)
The OSGi Framework Multiplication
- 1. Chapter 4.2 - Draft, Verse 138 : The Framework Multiplication Clement Escoffier, akquinet A.G.
- 2. akquinet akquinet AG akquinet €1300k SE business consulting GmbH €60k SE International Microsoft / .NET Outsourcing JAVA / SAP Associate Partners akquinet akquinet akquinet akquinet BMC GMBH IBS dynamic solutions outsourcing it-agile cimt AG GmbH €250k SE GmbH €300k SE gGmbH €250k SE GmbH €100k SE DoubleC GmbH akquinet akquinet akquinet akquinet IBS Brüssel SLS logistics system integration tech@spree Groupconcept GmbH GmbH €40k SE GmbH €250k SE GmbH €125k SE GmbH €300k SE infodesign GmbH akquinet akquinet panoptimum GmbH eurosoft Sp. z o.o. enterprise solutions €100k SE GmbH €80k SE Portal Systems GmbH HKS PortivITy GmbH GmbH €75k SE w//Center GmbH Partner Power International GmbH akquinet AG 2002 2003 2004 2005 2006 2007 Budget 2008 In association 2007 Partnerbeteiligung Staff 64 108 133 165 170 203 315 Staff 433 2 The Framework Multiplication
- 3. Modular and Mobile Solutions Competence Center focusing on Modular Systems Modularization expertise OSGi-based Sophisticated, Large scale, Distributed systems Mobile Solutions In the large MobileDevices, Interactions middleware, Server-side … M2M, Data collection and Mediation, Control loop Technologies iPHONE / Android OSGi (Apache Felix, Apace Ace, OW2 Chameleon, Apache Sling…) Java EE (JBOSS, OW2 JOnAS) 3 The Framework Multiplication
- 4. Why multiple OSGi frameworks in one VM ? OSGi has made a successful breakthrough Bundle (packaging and Service binding THE module layer on the top of deployment unit) (loose-coupled, Java dynamic) Wide spread usages as middleware kernel Mobile devices Desktop applications Lightweight Application servers Enterprise Application Servers More and more used by OSGi™ framework application themselves Modularity Java Virtual Machine Dynamism Provisioning 4 The Framework Multiplication
- 5. Why ? - Runtime/ Application isolation Conflicts ! Internal / Private API exposed by the middleware used unexpectedly by the applications Version conflict on third- party libraries OSGi™ framework Java Virtual Machine 5 The Framework Multiplication
- 6. Why ? – Application Model composite { Creation of composite Install-Bundle: Deployment packages++ foo; bundle-version=[1.0.0,1.2.0), bar; bundle-version=[1.0.0,1.0.0] Allows to describes Import-Package: waz; version=2.0.0 applications Export-Package: baz; version=1.0.1 } Exemple Such composites should be ran in an isolated child framework Child framework OSGi™ framework Java Virtual Machine 6 The Framework Multiplication
- 7. Why ? – Avoid applications conflicts Same issues as the middleware /applications conflicts Two applications may share services But sometimes …. NOT ! Stateful services Third-party library conflicts By using separate frameworks Guaranty a service isolation Guaranty a third-party libraries isolation 7 The Framework Multiplication
- 8. How do we solve that today ? The Launcher approach OSGi R4.2 has standardized how to create OSGi framework instances Framework Factory factory.newFramework(config) FWK 1 FWK 2 Launcher Java Virtual Machine 8 The Framework Multiplication
- 9. How do we solve that today ? The Child approach A bundle instantiates a new OSGi framework The lifecycle of this framework is managed by the bundle Relationships between the intra-bundle and the external world are managed by the bundle May be tricky…. OSGi Framework Bundle OSGi Framework Java Virtual Machine 9 The Framework Multiplication
- 10. Does this work ? In simple cases … YES In sophisticated cases …. Absolutely NO Cross-framework singleton bundle ? A singleton bundle may be resolved several times on the JVM URL Streams have to be multiplexed The JVM supports only ONE extension of the URL class What happens if several framework provide several times the same URL Handler ? The Security Manager is a JVM Singleton The condition permission admin directly uses the JVM security No way to adapt the security policy per framework 10 The Framework Multiplication
- 11. The RFC 0138 Multiple Frameworks In One JVM OSGi R4.2 RFC Not pushed in the OSGi R4.2 because of some direct impacts on the framework Will be somewhere in OSGi R5 Assumption Each framework manages its own class space, and is responsible for managing the lifecycle and resolution of its bundles. Class reachability inside the framework is managed by bundle resolution and classloading rules Class reachability outside the framework is managed by standard classloading rules and hierarchies 11 The Framework Multiplication
- 12. Child Framework Define a way to create child frameworks Created thanks to a Framework service (CompositeBundleFactory) Similar to the Launcher API Framework configuration Composite Manifest 12 The Framework Multiplication
- 13. Composite Manifest A Composite Manifest may contain Bundle-Version and Bundle-SymbolicName Import-Package from the parent framework Export-Package from the child to the parent CompositeServiceFilter-Export Exports services from the child to the parent Equivalent to iPOJO exports CompositeServiceFilter-Import Imports a service from the parent to the child Equivalent to iPOJO imports No way to install bundles directly in the composite At least in the last version of the RFC Allows to define your ADL, to choose your provisioning mechanism... Can be done with the framework configuration map 13 The Framework Multiplication
- 14. The parent – child relationship Child frameworks managed by A composite bundle Child Framework Representing the child into the parent Surrogate Bundle A surrogate bundle Representing the parent into the child Composite Bundle OSGi Framework Java Virtual Machine 14 The Framework Multiplication
- 15. Surrogate & Composite Bundles The Surrogate represents the parent framework into the child framework Publishes imported services into the child service registry Exports imported packages TheComposite represents the child framework into the parent framework Publishes exported services into the parent service registry Exports exported packages 15 The Framework Multiplication
- 16. Singleton Multiplexing Propose a way to multiplex URL Handler without conflicts Objective Resolve URL by using the ‘adequate’ URL Handler Already done inside Felix Analyze from the stack trace which Framework triggers the URL resolving Use the good URL Handler service 16 The Framework Multiplication
- 17. What else ? … RFC not included into OSGi R4.2 Break the system bundle lifecycle (RESOLVED state ?) Impact the core specification Surrogate bundles are complex Why not reusing the System Bundle ? The specification does not cover all use cases Security ? Others singletons ? However, it’s still a work in progress… 17 The Framework Multiplication
- 18. Conclusion Beingable to launch several frameworks inside the same VM is definitely required But it’s not so simple ! The RFC 0138 proposes a first draft addressing the issues Child framework creation and management Singleton multiplexing However, it’s far from complete And complex to implement… 18 The Framework Multiplication
- 19. What might be cool A real composite bundle description language ADL Abstract placeholder Dynamism, Substitution Creating a bridge with the deployment admin A deployment package could create a child framework Sandbox mechanism Like on the iPHONE 19 The Framework Multiplication
- 20. Questions ? Karl Pauls Dr. Clement Escoffier karl.pauls@akquinet.de clement.escoffier@akquinet.de Bülowstraße 66, 10783 Berlin Bülowstraße 66, 10783 Berlin +49 151 226 49 845 +49 175 2467717 20 The Framework Multiplication