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移动 agent 通信协议的 设计与分析

移动 agent 通信协议的 设计与分析. 答 辩 人： 冯 新 宇 指导教师：吕 建 教授 南京大学计算机软件研究所 2002 年 6 月 4 日. Outline of Presentation. Introduction: Inter-Agent Message Passing ARP: Design and Analysis Generalization: A Generic Framework Conclusion and Future Work. Introduction: Basic Concepts. Mobile Agents

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移动 agent 通信协议的 设计与分析

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  1. 移动agent通信协议的设计与分析 答 辩 人： 冯 新 宇 指导教师：吕 建 教授 南京大学计算机软件研究所 2002年6月4日

  2. Outline of Presentation • Introduction: Inter-Agent Message Passing • ARP: Design and Analysis • Generalization: A Generic Framework • Conclusion and Future Work

  3. Introduction: Basic Concepts • Mobile Agents • Mobile Agents are autonomous objects or object clusters, which are able to move between locations in a so-called mobile agent platform. (Mole, U of Stuttgart) • Mobile Agent Platform • A mobile agent platform is a distributed abstraction layer that provides the concepts and mechanisms for mobility and communication on one hand, and security of the underlying system on the other hand.

  4. Why Message Passing • Mobile Agent System can be used as General-Purpose Distributed Computing Middleware Platform. • Sometimes Message Passing is more efficient than migration • There DO exist MA-based applications that needs remote message passing between cooperating agents.

  5. Inter-Agent Message Passing- Requirements • Location Transparency • Message sender does not need to know the physical location of the receiver agent, whose address changes frequently by moving from one host to another. • Reliability • The concurrent and asynchronous nature of message forwarding and agent migration may cause message loss or chasing problem. • By reliability we mean the message can reach the target agent by a bounded number of forwarding.

  6. MAP ? MAP MAP MAP

  7. Inter-Agent Message Passing- Requirements • Efficiency • Low location updating overhead • Low message delivery overhead • Asynchrony • Asynchronous execution • Little constraint on the mobile agent mobility. • Adaptability • Suit different Communication and Migration Pattern

  8. Introduction: Inter-Agent Message Passing • ARP: Design and Analysis • Design of ARP • Analysis of ARP • Improvements • Generalization: A Generic Framework • Conclusion and Future Work

  9. Design of ARP (Adaptive and Reliable Protocol) • Mobile IP solution • Extention1: Mobile IP + Synchronization • Extension2: Distributed Home Scheme • Extension3: Mailbox-Based Scheme = ARP

  10. Reg Mobile IP Solution MAP MAP-Home MAP MAP

  11. Design of ARP • Mobile IP solution • No Reliability Support • Extention1: Mobile IP + Synchronization • The agent home coordinates message passing and agent migration • Extension2: Distributed Home Scheme • Extension3: Mailbox-Based Scheme = ARP

  12. ACK Reg Dereg Mobile IP + Synchronization MAP MAP-Home MAP MAP

  13. ACK Reg Dereg Mobile IP + Synchronization MAP MAP-Home MAP MAP

  14. ACK Dereg Mobile IP + Synchronization MAP MAP-Home MAP MAP

  15. Mobile IP + Synchronization • Pros • Simple • Guarantee reliable message delivery • Agent has received all the message on transmission before migration • Message forwarding is suspended during agent migration • Cons • Rely too much on the agent home • Performance bottleneck • Single-point-of-failure • Asynchronous execution • Triangle Routing

  16. Design of ARP • Mobile IP solution • Extention1: Mobile IP + Synchronization • Extension2: Distributed Home Scheme • Decentralize the role of agent home to all the hosts on the migration Path • Caching Mechanism • Extension3: Mailbox-Based Scheme = ARP

  17. Distributed Home Scheme MAP-1 MAP-2 MAP-3 MAP-5 MAP-4

  18. Distributed Home Scheme MAP-1 MAP-2 MAP-3 MAP-5 MAP-4

  19. Distributed Home Scheme MAP-1 MAP-2 MAP-3 MAP-5 MAP-4

  20. Caching Mechanism MAP-1 MAP-2 MAP-3

  21. Distributed Home Scheme • Pros • Location Transparency, Reliability • Reliance on the agent home is reduced • Locality of Communication (No Triangle Routing) • Cons • Migration Cost is Un-Affordable • Delay of Migration is prohibitive

  22. Design of ARP • Mobile IP solution • Extention1: Mobile IP + Synchronization • Extension2: Distributed Version • Extension3 (ARP): Mailbox-Based Scheme

  23. Design of ARP-The Mailbox-Based Scheme MB MAP MAP MAP

  24. Design of ARP-The Mailbox-Based Scheme • Communication between agents is divided into two steps • Message transmission from the sender to the receiver’s mailbox • Identical with inter-agent Communication • Distributed Home Scheme is used • Delivery of the message from the mailbox to its owner agent • Push or Pull

  25. ARP-Adaptive and Reliable Protocol MB MB MAP-1 MAP-2 MAP-3 MB MB MAP-4 MAP-5 MAP-6

  26. MB MB MAP-1 MAP-2 MAP-3 MB MB MAP-4 MAP-5 MAP-6

  27. MB MB MAP-1 MAP-2 MAP-3 MB MB MAP-4 MAP-5 MAP-6

  28. Properties of ARP • Location Transparency • Home + Caching Mechanism • Reliability • Synchronization is used • Asynchronous Migration • Adaptability • Mobile IP + Synchronization • Distributed Home Scheme • Efficiency

  29. Introduction: Inter-Agent Message Passing • ARP: Design and Analysis • Design of ARP • Analysis of ARP • Improvements • Generalization: A Generic Framework • Conclusion and Future Work

  30. ARP: Design and Analysis • Analysis • Migration of the mailbox • When to migrate • Impact of migration frequency on the performance • Interaction between the mailbox and the agent • Push or Pull • Improvement • Path Compression and Garbage Collection • Fault-Tolerance Issues

  31. Impact of the migration frequency on the performance

  32. Introduction: Inter-Agent Message Passing • ARP: Design and Analysis • Generalization: A Generic Framework • Design Space of the mailbox-based scheme • Three-Dimensional Framework • Particular Protocols • Conclusion and Future Work

  33. Design Space of the Mailbox-based Scheme • Migration of the mailbox • Interaction between the agent and its mailbox: Push or Pull? • Synchronization • Sender The mailbox • The mailbox Its owner agent

  34. Y (Delivery Mode) PS PL X (Migration Frequency) NS JM FM NM SHM (SMA) FS Z (Synchronization) Generalization – A Generic Framework

  35. The Generic Framework-Particular Protocols • Parameter Combination • The three dimensions are orthogonal • Protocol: XX-YY-ZZ • Home-Server Based Protocols • NM-PS-NS: Identical to Mobile IP • NM-PS-SMA: Mobile IP + Sync • NM-PL-NS: Pull mode is used

  36. Forwarding Pointer Based Protocols • FM-*-NS • JM-PL-NS • JM-PS-NS • Distributed Registration-Based Protocols • FM-*-SHM (Distributed Home Scheme) • JM-PS-FS • JM-PL-SHM (ARP) • When to use which protocol?

  37. Conclusion and Future Work • The mailbox based scheme introduces • Flexibility and adaptability • Reduction of the constraint on the agent mobility. • Better balance between migration cost and message delivery cost

  38. Conclusion and Future Work • Based on the scheme • The Generic Framework can be used to: • Describe and evaluate various MA communication protocols • Help users to clearly specify their requirements • Help users to design flexible and adaptive protocols which can be customized to meet their requirements • The ARP protocol derived from the framework can satisfy the requirements of a protocol • Location Transparency • Reliability • Asynchrony • Efficiency and Adaptability

  39. Conclusion and Future Work • Future work • Modeling mobility of mobile agents • Extend the mailbox-based scheme for mobile agents multicast

  40. 致谢 • 感谢参加答辩的各位老师 • 感谢我的导师吕建教授三年来的谆谆教诲 • 感谢陶先平博士对我工作上的指导和帮助 • 感谢软件所其他老师和各位同学对我生活和学习上的关心和帮助

  41. 发表论文和参加项目 • 发表论文 • 一种改进的移动agent通信算法，计算机学报，Vol.25, No. 4, 2002, pp. 357-364 • An Efficient Mailbox-Based Algorithm for Message Delivery in Mobile Agent Systems， Proc. of MA2001, pp. 135-151 • 参加项目 • 基于Internet的移动agent技术及其在电子商务中的应用 • Design of Efficient Mobile Agent Communication Protocols

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