Distributing OSGi


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OSGi 4.2- Early Draft RFC-119 (with a twist of Terracotta)

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Distributing OSGi

  1. 1. Distributing OSGi™ OSGi 4.2- Early Draft RFC-119 (with a twist of Terracotta)
  2. 2. So who is Bram? Bram de Kruijff Computer Science / Cognitive Science Lead Architect GX R&D Mainly interested in web x.y, Java™, Linux, Open Source, Open Standards Bram.deKruijff@gxwebmanager.com
  3. 3. … and what is GX? GX creative online development Web Content Management Nijmegen, Amsterdam, Eindhoven, Boston Founded in 1995, first (Java™) CMS in 1998 GX WebManager 9 powered by OSGi™ http://www.gxwebmanager.com http://www.gxdeveloperweb.com
  4. 4. Today’s menu! Problem statement OSGi™ Architecture Distributed OSGi™ Demo setup Code & Demo Questions & discussion
  5. 5. Problem statement How do we scale OSGi™ based application without loosing flexibility at runtime or violating the service programming model? •Sharing object caches between nodes •Manage deployment over multiple nodes •Manage application state over multiple nodes •Service collaboration over multiple nodes
  6. 6. OSGi™ Architecture OSGi™ Architecture • Security • Modules • Life Cycle • Service Registry • Services “OSGi provides an inVM collaborative SOA model”
  7. 7. Distributed OSGi™ RFC 119 addresses the need for OSGi™ applications to operate in heterogeneous IT environments •Allow OSGi™ services to publish themselves and be invoked from outside their own runtime •Allow OSGi™ services to discover and consume services outside their own runtime
  8. 8. Distributed OSGi™ Example of a remote system invoking a service inside the OSGi™ runtime Source: OSGi specification
  9. 9. Distributed OSGi™ Example of a an service inside the OSGi™ runtime invoking an external service Source: OSGi specification
  10. 10. Distributed OSGi™ Example using this mechanism for communication between multiple OSGi runtimes Source: OSGi specification
  11. 11. Distributed OSGi™ Hey! I can do that using <enter favorite middleware product here> too! True, but… Distributed OSGi™ standardizes the mechanism, abstracts away from implementation specifics and keeps the OSGI™ service programming model intact
  12. 12. Distributed OSGi™ OSGi™ service programming model is kept intact! •Remotable services simply publish their Java service interface with the service registry •Remote services are published through standard service registry •Discovery and distribution through standard service interfaces
  13. 13. Distributed OSGi™ Local services for distribution and discovery Source: OSGi specification
  14. 14. Distributed OSGi™ Responsibilities of the DistributionProvider service: •Monitor availability of local remotable services •Publish local remotable services with Discovery •Publish local endpoints for remote services •Handle local service invocation of remote services •Handle remote service invocation of local services
  15. 15. Distributed OSGi™ Responsibilities of the Discovery service •Discover available remote services •Monitor availability of remote services •Notify DistributionProvider of changes •Publish services in remote serviceregistries
  16. 16. Distributed OSGi™ Leveraging Service Registry Hooks (RFC 126) •PublishHook – filtering service lifecycle events before delivery •FindHook – filtering service references before return •ListenerHook – monitoring service registry listener registrations
  17. 17. Distributed OSGi™ Interaction example Source: OSGi specification
  18. 18. Distributed OSGi™ Metadata and configuration •org.osgi.remote.publish – indicates that a service is to be made available •org.osgi.remote.intents – list of (qualified) intents for the published service •org.osgi.remote.configuration.type – type of additional metadata Additional configuration is done at deployment time through the DSW software
  19. 19. Distributed OSGi™ Conclusion •Spec is still in early draft •Nice fit wit existing service model •Open and focused on collaboration •Service Registry Hooks are very powerful And it works  •Apache CXF (Reference Implementation) •Apache Tuscany (Work in progress) •GXLabs JSpring 2009 demo!
  20. 20. Demo setup To get things started we need an OSGi™ runtime and some kind of middleware •OSGi™ framework •JVM level clustering •Open source (ASL) •Open source (TPL) •Small footprint •Non invasive •Very stable •Lightweight
  21. 21. Demo setup To meet our objectives we are going to create several services •MessageBus – Simple messaging service infrastructure based on collections clustered by Terracotta •DeploymentManager – Bundle deployment service that allows cluster wide deployment of bundles using the MessageBus •DistributionProvider – DSW implementation that remotes calls using the MessageBus •Discovery – Implementation of the Discovery service that communicates over the MessageBus
  22. 22. Demo setup More then a thousand words OSGi runtime 1 TC OSGi runtime 2 Discovery Discovery Message Message BUS Bus Bus Distribution Distribution Provider Provider Distribution Cache Cache Cache Distribution Manager Manager (1..n) Manager Manager
  23. 23. Demo & Code
  24. 24. Q&A For more info on GX WebManager 9 have a look at http://www.gxdeveloperweb.com