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Automated Negotiation for Grid Notification Services

Automated Negotiation for Grid Notification Services. Richard Lawley, Keith Decker, Michael Luck, Terry Payne and Luc Moreau Intelligence, Agents, Multimedia Group School of Electronics & Computer Science University of Southampton ral01r@ecs.soton.ac.uk. Outline. Introduction

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Automated Negotiation for Grid Notification Services

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  1. Automated Negotiation for Grid Notification Services Richard Lawley, Keith Decker, Michael Luck, Terry Payne and Luc Moreau Intelligence, Agents, Multimedia Group School of Electronics & Computer Science University of Southampton ral01r@ecs.soton.ac.uk

  2. Outline • Introduction • Notification Services • Negotiation • Negotiation Engine • Evaluation of Negotiation Engine • Future Work & Conclusion Automated Negotiation for Grid Notification Services

  3. Introduction • Providers need to inform clients of: • Changes to database content • New releases of tools or services • State changes in long-running jobs • Message-Oriented Middleware layer • Provider notifies middleware layer • Middleware layer informs clients • e.g. MQ Series, JMS, MSMQ Automated Negotiation for Grid Notification Services

  4. Information is published on a topic Consumers subscribe to an information topic Publishers publish information on a topic Updates are sent to subscribers Publish-Subscribe Model S1 NS P1 S2 Publisher Notification Service Subscriber Automated Negotiation for Grid Notification Services

  5. Notification Services • Message-Oriented Middleware layer using Publish-Subscribe model • Responsible for asynchronous delivery of messages between publishers and subscribers • Can Filter & Combine Notifications allowing selective notifications and regular digest delivery Automated Negotiation for Grid Notification Services

  6. Notification Service Examples • Grid Monitoring Architecture (Tierney, Aydt, Gunter, Smith, Swany, Taylor and Wolski 2002) • Grid Notification Framework (Gullapalli, Czajkowski and Kesselman 2001) • OGSA Notification Framework (JaiPaul 2003) • NaradaBrokering (Fox and Pallickara 2001) • myGrid Automated Negotiation for Grid Notification Services

  7. myGrid • e-Science project aimed at Bioinformatics • Workflow-based in-silico experiments • Workflow specified how an experiment should be composed • Experiments can be long-running • Notification Service communicates results • NS also used between services Automated Negotiation for Grid Notification Services

  8. myGrid - Bioinformatics • Bioinformatics is data-intensive • SWISS-PROT Protein Knowledgebase • Over past 14 months has grown by 20%, with approximately 200 changes per day  Constantly expanding • Query to find new annotations or sequences that are similar to existing sequences Automated Negotiation for Grid Notification Services

  9. Notification Services - Problems • Providers and Consumers can specify QoS constraints • Notification frequency • Price paid • Mismatch in preferences of provider & consumer • Consumer wants updates immediately and for free • Producer wants to publish regular updates and charge • Notification Services do not address this problem • Negotiation can find mutually acceptable values Automated Negotiation for Grid Notification Services

  10. Negotiation • “The process by which two or more parties exchange proposals in order to reach a mutually acceptable agreement on a particular matter” • Components of negotiation • Item – the object under negotiation • Proposals – set of values suggested by one party • Preferences – values acceptable to a party • Utility functions – a method of evaluating the utility of a particular proposal Automated Negotiation for Grid Notification Services

  11. Negotiation • Negotiation Protocols • Set of rules governing a negotiation • Types of participants • Valid negotiation states & actions • Negotiation Strategies • How a participant will behave (within protocol) • How to generate proposals • When to accept proposals Automated Negotiation for Grid Notification Services

  12. Negotiation • Cooperative Negotiation • Preferences and utility functions shared • Social Welfare (benefit to all parties) is primary objective • Competitive Negotiation • Private preference and utility functions • Personal benefit is primary objective • Competitive Negotiation chosen for Notification Service • Hard to share utility functions & preferences if they depend on locally-sensed environmental factors • Notification Service may be used in competitive environment, e.g. service providers competing for business Automated Negotiation for Grid Notification Services

  13. Negotiation Engine – Definitions • Negotiations are between requester and requestee • Conditions negotiated over are negotiation terms • A proposal contains values for negotiation terms • Conversation between requester & requestee is a Negotiation Thread • Number of proposals exchanged is the Negotiation Thread Length • Preferences specify acceptable ranges • Ideal value – sensible “ideal world” value • Reservation value – limit of acceptability Automated Negotiation for Grid Notification Services

  14. Negotiation Process Automated Negotiation for Grid Notification Services

  15. Negotiation Model • Bilateral Service-Oriented Negotiation Model • Based on Negotiation Decision Functions (Faratin, Sierra & Jennings 1998) • Automated negotiation using external factors in proposal generation/evaluation • Model only handles negotiation protocol • External program provides inputs to proposal generation & evaluation process Automated Negotiation for Grid Notification Services

  16. Negotiation Model • Proposals generated by tactics and strategies • Tactics – function evaluating a single negotiation term • Time-dependant • Resource-dependant • Imitative • Strategies – way of weighting different tactics • Can vary over course of negotiation • Favour time-dependant tactics towards deadline • Proposal utility = weighted summation of utility of each term in proposal • Proposal accepted when U(Pincoming) > U(Pgenerated) Automated Negotiation for Grid Notification Services

  17. Evaluation of Negotiation Engine • Evaluate suitability for Notification Service • Experiment setup based on original evaluation • Variables grouped into environments • Preferences and Deadlines • Repeatedly running in same environment yield identical results • Range of environments generated and used for all of the experiments • Single tactic used for each party • All tactics played against each other Automated Negotiation for Grid Notification Services

  18. Exp1: Variable Deadline • “What affect does varying the deadline have on utility and success rate?” • Deadlines measured in number of messages • No communication overhead in test setup • Vary deadline (1-100 messages). Measure utility and success rate. • Hypothesis – Utility and success rate will be poor with shorter deadlines. Automated Negotiation for Grid Notification Services

  19. Exp1: Variable Deadline – Results • Higher utilities achieved with longer deadlines • Approaches optimal utility • Higher success rates with longer deadlines • Moves towards 100% success rate Automated Negotiation for Grid Notification Services

  20. Exp1: Variable Deadline - Results • Plot time used against utility achieved • Utility increases as time used decreases • Explained by plotting overlap of prefs (Φ) against messages Automated Negotiation for Grid Notification Services

  21. Exp2: Multiple Terms • Negotiations typically over many terms • e.g. price, duration, frequency • Is Utility affected by number of terms? • Number of terms varied between 1 and 25 • All terms weighted equally • Deadline varied between 30 and 60 (random) • Record utilities and execution time (CPU time) Automated Negotiation for Grid Notification Services

  22. Multiple Negotiation Terms - Results • As number of terms increases, utility remains fairly constant • Only valid when all terms weighted equally • Execution time is linearly related to the number of terms Automated Negotiation for Grid Notification Services

  23. Exp3: Execution Time • Is execution time linearly related to number of messages? • Deadlines varied between 30 and 60 • Minimum, average (over 100 runs) and maximum execution times measured for each deadline • Communication delays are ignored as in test setup components are coupled directly together Automated Negotiation for Grid Notification Services

  24. Exp3: Execution Time - Results • Minimum and mean execution times linearly related to number of messages • Maximum execution time has unpredictable peaks • Garbage collection? • Only in minority of cases as mean is close to minimum Automated Negotiation for Grid Notification Services

  25. Notification Service Example • Example from Bioinformatics field • SWISS-PROT Protein Knowledgebase • Over past 14 months has grown by 20%, with approximately 200 changes per day  Constantly expanding • Query to find new annotations or sequences that are similar to existing sequences Automated Negotiation for Grid Notification Services

  26. Notification Service Example • Assumptions • 1000 Subscribers, each with 100 sequences they want matched • Searches can be run iteratively to refine results • Subscriber would like to be notified of changes every 5 hours Automated Negotiation for Grid Notification Services

  27. Notification Service Example • By accepting subscriber requests, 5,000,000 searches per day required • Use negotiation over two terms: • Frequency (time between notifications) • Provider preference: 168-24 hours • Subscriber preference: 5-120 hours • Number of iterations • Provider preference: 1-3 • Subscriber preference: 5-1 Automated Negotiation for Grid Notification Services

  28. Notification Service Example • Provider preferences kept constant • Consumer preferences vary by a small random amount • Deadlines between 30 and 60 messages • After running negotiations: • Average Frequency: 67.6 hours • Average Iterations: 2.31  651,000 searches per day (87% reduction) Automated Negotiation for Grid Notification Services

  29. Notification Service Example • Number of queries required for each outcome plotted against provider utility • Shows how utility decreases as the number of queries increases Automated Negotiation for Grid Notification Services

  30. Notification Service Example • Greater utility is represented by needing to do fewer queries for a provider • Using Negotiation allows the provider to increase their utility and still satisfy needs of consumer • Introducing Negotiation may reduce consumer utility, but would allow more consumers to be serviced Automated Negotiation for Grid Notification Services

  31. Future Work • Peer-to-peer Notification Services • Notification Services talking to Notification Services • Consumers subscribing to single service, receiving updates from elsewhere NS1 NS2 P2 S1 Publisher Notification Service S2 P1 NS3 Subscriber NS4 Automated Negotiation for Grid Notification Services

  32. Future Work • Support negotiations for peer-to-peer notification service by supporting chained negotiation • Negotiations with intermediaries • Negotiations where intermediaries may be able to satisfy request with existing commitments • Integrate with myGrid Notification Service Automated Negotiation for Grid Notification Services

  33. Conclusion • Negotiation in a Notification Service allows differences in QoS preferences to be resolved • Negotiating over QoS allows a provider to support more clients Automated Negotiation for Grid Notification Services

  34. Questions? Automated Negotiation for Grid Notification Services

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