Dynamic Service Aggregation in Heterogeneous Grids

1. Dynamic Service Aggregation in Heterogeneous Grids Stavros Isaiadis and Vladimir Getov University of Westminster HSCS PhD Workshop, 29th June 2007 s.isaiadis@wmin.ac.uk, v.s.getov@wmin.ac.uk

2. Outline • Overview/Background • Hybrid Grid Systems • Lightweight Server-side Container (LSC) • Aggregator Framework • Case Study • Evaluation • Conclusion

3. Outline • Overview/Background • Hybrid Grid Systems • Lightweight Server-side Container (LSC) • Aggregator Framework • Case Study • Evaluation • Conclusion

4. What is the Grid? • A distributed computing infrastructure that enables on-demand, cross-organizational resource sharing -a virtual supercomputer?

5. Objectives • Integration of mobile and small-scale devices into Grid systems as service providers (and not just consumers!) • Extend the Grid towards the less powerful but more flexible end of the spectrum • Encapsulate the inherent dynamicity and provide high-level views and programming abstractions • Ultimate vision: A truly pervasive hybrid Grid system

6. Why Mobile and Small Devices? • Unique Functionality • context and location awareness • multimedia cameras • intelligent wireless sensors • Global Positioning Systems • Flexibility • Extend to new geographical areas • Move business outside • Interactive and Personalized Services • With mobile phones, administrators are always near their services • Attach status and context to services

7. Outline • Overview • Hybrid Grid Systems • Lightweight Server-side Container (LSC) • Aggregator Framework • Case Study • Evaluation • Conclusion

8. Classes of Hybrid Systems • mobile interfaces to grid resources where mobile devices are merely interfaces to functionality available in the Grid system, and do not contribute any services. • exploitation of raw resources focus is on distributing applications for parallel execution usually requiring the partitioning of the application into small independent tasks. • exploitation of services and flexibility focus is on supporting mobile services in a SOA system, while also enabling small-scale devices to contribute services towards a fully integrated infrastructure.

9. Hybrid Systems Application Client, User Tools Developer Application Layer Fabric Layer Mobile and Small-Scale Devices Typical “Static” Services

10. Challenges • Grid systems have typically evolved around High Performance Computing. As a result, Grid developers have assumed: • A plethora of available static resources • Fast and reliable networking infrastructure • Currently very restricted and very few service middleware for small scale devices • Based on Web Services (slow and resource demanding) • Java RMI (restrictions and dependencies) • Cannot consider each mobile device as a full Grid system member! • Very unreliable • Limited individual contribution

11. Contribution • A Lightweight Service Container suitable for limited devices • Performance-oriented • No dependencies • Easy deployment • But: non-interoperable, low-level. What do we do? • Related Work: • Mobile OGSI.NET • Obsolete, restricted model, complex deployment • Microservices • Very complex deployment, not very fast (WS-based) • Racoon • Promising for small Web Services (still in progress), but not very fast • WSKPeer • Promising hybrid Service/P2P approach, work in progress –no workable version

12. Contribution (contd.) • An Aggregator framework to enable the efficient integration of mobile devices. An Aggregator provides: • A proxy to a group of heterogeneous and mobile fabric services • an abstraction layer that hides the dynamicity and heterogeneity of the mobile services • a high-level view of a virtually stable and reliable entity, despite the unreliable nature of the inner fabric services • Related Work: • ?

13. Contribution (contd.) Application Client, User Tools Developer Application Layer Aggregators Development API Fabric Layer Proxy Layer Mobile and Small-Scale Devices

14. Outline • Overview • Hybrid Grid Systems • Lightweight Server-side Container (LSC) • Aggregator Framework • Case Study • Evaluation • Conclusion

15. Lightweight Server-side Container (LSC) • Small CPU and memory footprint • Simpler services • not complex operations • no build in support for complex data types (currently) • No software dependencies • only J2ME running! • for easy deployment • Permanent and Stateful approach • To support context-awareness • To simplify lifecycle management • To reduce concurrent client connections and thus resource requirements • Friendly GUI for easy service registration

16. Mobile Device Proxy Server Socket Listener Socket Communicator TCP Socket Server Request Handler Service Request Translator Service Registry Service Container Selector Service Interfaces Server Side Components Java Bean Java Class Other Java LSC Stack

17. Outline • Overview • Hybrid Grid Systems • Lightweight Server-side Container (LSC) • Aggregator Framework • Case Study • Evaluation • Conclusion

18. Aggregator Framework Design Requirements: • Encapsulate the big cardinality of the mobile domain • Provide reliability and availability • Encapsulate heterogeneity and dynamicity • Must enable a high-level abstract view VIRTUAL CLUSTER HTTP/SOAP TCP/LSC CLIENT PROXY

19. Aggregator/Virtual Clusters Architecture Application Client, User Tools Developer Application Layer Aggregator + Platform Service Interfaces Development API Aggregator + Platform Services Collective Layer VC Platform/ Proxy Layers Fabric Layer Groups of Mobile and Small-Scale Devices

20. Dynamic Service Aggregation

21. Outline • Overview • Hybrid Grid Systems • Lightweight Server-side Container (LSC) • Aggregator Framework • Case Study • Evaluation • Conclusion

22. Case Study • Dynamic Content Aggregation from Multiple Heterogeneous Mobile Sources • Phase 1: providers must register their services with an Aggregator • Phase 2: registered services are automatically activated when they are within the “neighbourhood” of an Aggregator • Phase 3: clients can now use that Aggregator (WS) to gather content without knowledge of the underlying fabric level details

23. Phases 1 and 2: Registration and Activation Providers specify the shared services • Server-side Framework (WS, RMI, LSC, Other) • Implementation class • Interface location • Human readable description They can then enable sharing on the press of a button • Services are discovered by the relevant Aggregator and activated automatically • Services are now shared!

24. Phase 3: Invocation

25. Outline • Overview • Hybrid Grid Systems • Lightweight Server-side Container (LSC) • Aggregator Framework • Case Study • Evaluation • Conclusion

26. LSC Evaluation: Performance Testing

27. LSC Evaluation: Resource Requirements

28. Outline • Overview • Hybrid Grid Systems • Lightweight Server-side Container (LSC) • Aggregator Framework • Case Study • Evaluation • Conclusion

29. Conclusions • The LSC framework manages to marry the high performance of low-level TCP sockets with the interoperability of the standards-based Web Services paradigm • Evaluation has shown that resource requirements are minimal, and there are no software dependencies or complex installation procedures • The Aggregator framework: • enables high-level abstract views of the mobile devices • Provides a virtually stable and reliable virtual entity despite consisting of unreliable fabric services • With the rapid evolution of mobile computing and related advances, the time is right to provide the foundations for truly pervasive systems

30. Thank You! Questions? The Virtual Clusters Project page: http://www.isaiadis.com/vc/ Please forward any suggestions, questions, comments to: s.isaiadis@wmin.ac.uk