Automated Negotiation for Grid Notification Services

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