1. Performance Evaluation of a SNAP-based Community Resource Broker Mohammed H. Haji, Peter Dew, Karim Djemame and Iain Gourlay

2. Outline DAME Project (Distributed Aircraft Maintenance Environment) Current challenges within Grid middleware Grid Resource Brokers Service Negotiation Acquisition Protocol Use of a Knowledge bank Three-phase Commit protocol Performance results Conclusion and future work

3. DAME Project (Distributed Aircraft Maintenance Environment) DAME is a joint project Four Universities, Leeds, York, Sheffield and Oxford Industrial partners are Rolls Royce, Data Systems and Solutions and Cybula Ltd This project aims to build a distributed diagnostics decision support system, for the use of Virtual Organisations (VOs), based on Grid technology

4. Current Challenges within Grid Middleware There are many complexities in-order to submit a simple Grid job: Have the ability to query local and remote resource Information Providers Identify and filter out the appropriate resources for the job Co-allocate the job Secure the resources Submit the job Monitor and police the active job

5. Grid Resource Brokers A Resource Broker is a middleware entity that insulates the user from the Grid complexities Two broad categories of resource brokers:  System-centric which enhances system utilisation and throughput  User-centric which enhances computation and adheres to user requirements

6. Service Negotiation and Acquisition Protocol (SNAP) Observation User requirements through a Grid portal Resources QoS needs Policies Feedback on decisions made Resource availability Resources Active Job SLA Resource query/ Dispatch Monitor Policing Resource broker TSLA RSLA BSLA Task Service Level Agreement (TSLA ). Resource Service Level Agreement (RSAL). Binding service level agreement (BSLA). User requirements through a Grid portal Task Service Level Agreement (TSLA ) Resource broker Resource Service Level Agreement (RSLA) Resources Active Job SLA Monitor Binding Service Level Agreement (BSLA)

7. SNAP Development Resources Knowledge bank Matchmaker Co-ordinator Dispatcher Resource gatherer Decision maker Grid middleware RRRR Portal TSLA RSLA BSLA

8. Knowledge Bank (KB) Benefits of having a KB:  Facilitate the broker in supporting automated resource discovery  Alleviate the user from the burden of keeping a log of the resources  Enhance efficiency by avoiding unnecessary interaction with resources  The KB  stores a history profile of past performance of resources  enables the broker to differentiate and categorise the resources into different levels  An analogy to the KB is a telephone directory

9. Resources Knowledge bank Matchmaker Co-ordinator Dispatcher Resource gatherer Decision maker Grid middleware RRRR Portal TSLA RSLA BSLA Need to Secure Resources

10. Three-Phase Commit Protocol First phase  Contact the categorised resources which would either be tagged as white or blue Second phase  On receiving the information from all the contacted resources, the broker co-allocates the task  The selected resources are reserved and evolve into the amber state  The data is transferred Third phase  The information service updates the resource status to red and the job is bound to the resources and begins execution  Establish a socket connection for probing the dynamic information and keeping a vision of any resource status change Blue tagged resources White tagged resources Resources in the amber state Resources in the red state

11. Experimental Design and Performance Evaluation Objectives Investigate behaviour of both a simple SNAP broker and one using the three-phase commit protocol Performance evaluation Scenario 1 Resources appropriate for the job are taken and the broker must wait until they become free before submitting the job Case A  The information provider response time varies but the job duration is constant Case B  The information provider response time is constant but the job duration is varied Scenario 2 While the broker is in the process of making a decision as to where the job should be submitted the resources are taken

12. Results: Scenario 1 Case A Experiment 1

13. Results: Scenario 1 Case A Experiment 2

14. Results: Scenario 1 Case B Experiment 1

15. Results: Scenario 1 Case B Experiment 2

16. Results: Scenario 2 Experiment

17. Future Work To deploy the SNAP-based resource broker on the White Rose Grid (WRG) using the Three-phase commit protocol.

18. SNAP-based resource broker is a viable contender for use in future Grid implementations. Results indicate that in certain specific scenarios, three-phase commit protocol provides a performance enhancement over a simple SNAP- based broker. Further work would be to investigate the broker in a wider scenario space through mathematical modelling and simulation and for it to be deployed on the WRG. Conclusion

19. References M.H. Haji, P.M. Dew, K. Djemame, I. Gourlay. A SNAP-based Community Resource Broker using a Three-Phase Commit Protocol, 18th IEEE International Parallel and Distributed Processing Symposium, Santa Fe, New Mexico, April 2004. K. Djemame, M.H Haji, J. Padgett. SLA Management in a Service Oriented Architecture, 2004 International Conference on Computational Science and its Application, Assisi, Italy, May 2004. A. Othman, P. Dew, K. Djemame, I. Gourlay Adaptive Grid Resource Brokering, IEEE Cluster Computing, December 2003, Hong Kong.