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.

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