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Interoperating with Services in a Mobile Environment Andreas Dahl, andread@fi.uio.no

Presentation. Interoperating with Services in a Mobile Environment Andreas Dahl, andread@fi.uio.no Pål Rolfsen Grønsund, paalrgr@ifi.uio.no Per Thomas Kraabøl, pertk@ifi.uio.no. ReMMoC: A Reflective Middleware to Support Mobile Client Interoperability. Sam Samuel

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Interoperating with Services in a Mobile Environment Andreas Dahl, andread@fi.uio.no

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  1. Presentation Interoperating with Services in a Mobile Environment Andreas Dahl, andread@fi.uio.no Pål Rolfsen Grønsund, paalrgr@ifi.uio.no Per Thomas Kraabøl, pertk@ifi.uio.no

  2. ReMMoC: A Reflective Middleware to Support Mobile Client Interoperability Sam Samuel Global Wireless Systems Research, Bell Laboratories, Lucent Technologies,UK Paul Grace, Gordon Blair Distributed Multimedia Research Group, Computing Department, Lancaster University, UK

  3. Outline • The challenges for mobile computing middleware • Middleware heterogeneity • The ReMMoC approach • Reflection, components & component frameworks • Evaluation • Future work & concluding remarks

  4. The Challenges of Mobile Computing • The characteristics of the mobile environment present a number of challenges for middleware developers. For example: • Disconnection • Low & variable Bandwidth • Address Migration • Low Power • Small Storage Capacity • Middleware seeks to overcome these to better support distributed mobile applications.

  5. Mobile Computing Middleware • Different styles of mobile middleware have emerged to solve these challenges. • Asynchronous paradigms: • Publish-Subscribe (REBECA, STEAM) • Tuple Spaces (LIME, L2IMBO) • Context-based adaptation: • CHARISMA, OpenORB, Odyssey • Enhancements to established middleware: • RAPP, Alice, Dolmen (CORBA) & Wireless RMI (Java RMI) This explosion of middleware solutions creates middleware heterogeneity. No interoperability between different middleware styles.

  6. A Mobile Computing Scenario

  7. The ReMMoC Approach • A Reflective Middleware to support mobile client interoperability. • Find mobile services irrespective of the service discovery protocol • Interoperate with services implemented by different middleware types • Design of ReMMoC built upon three concepts: • Components (OpenCOM) • Reflection • Component Frameworks (CFs)

  8. Abstract Middleware ReMMoC abstract programming Model Binding mapping implementations Abstract to Concrete Discovery mapping implementations Binding type implementations Service Discovery CF Binding CF Concrete Middleware Service Discovery protocols Top-level ReMMoC CF The ReMMoC Architecture

  9. Component Frameworks in ReMMoC ILifeCycle IMetaInterface IConnections OpenCOM component framework ICFMetaArchitecture CF Service Interfaces (Can be exposed interfaces of internal components) CF receptacles (Can be exposed) Lock Interceptor Graph of internal components Validation Plug-in

  10. The Service Discovery Framework • Discover Services advertised by different protocols. • Dynamically reconfigures itself based upon current environment conditions. • Cycles through tests for known types of service discovery. • Single-personality – discovery performed over a single protocol type. • Multi-personality – discovery executed simultaneously over a number of types. • Current Implementations – UPnP and SLP lookup.

  11. The Binding Component Framework • Dynamic replacement of binding types (implemented as OpenCOM components) based upon information the from service discovery CF. • Configurations we’ve implemented - IIOP client, IIOP Server, SOAP client, subscriber, publisher

  12. Evaluation - Mobile Applications • Goal to develop a mobile application using ReMMoC that operates in different locations exhibiting middleware heterogeneity. • Three Applications implemented: • Jukebox, Chat Service, Sport News. • Different locations (e.g. Office & Home Environment). • Heterogeneous discovery protocols (UPnP & SLP). • Heterogeneous binding protocols (P/S, SOAP, IIOP). • The same application code (containing only abstract operations) operates continuously across different locations.

  13. Evaluation – Memory Capacity • Mobile devices are resource light and reflection is expensive; why not reconfigure at the server side?

  14. Future Work • Dynamic component downloading architecture based upon context information. • Extension to include other binding paradigms: • Tuple spaces, data-sharing, multimedia streaming etc. • Integration with resource management architecture. • Evaluation using more complex applications: • Ambient intelligent environments, ubiquitous computing. • Investigate Web Service description formats that include non-functional aspects (e.g. Web Services Endpoint Languages) and more complex interaction patterns (e.g. Web Services Flow Language).

  15. Concluding Remarks • Mobile environments contain heterogeneous middleware • ReMMoC developed to support application developers in face of this type of heterogeneity • Reconfiguration of binding and service discovery • Evaluated and demonstrated across a set of mobile applications: • Jukebox • Chat service • Sport News Service

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