Novel Directory Service and Message Delivery Mechanism Enabling Scalable Mobile Agent Communication

Jinho Ahn

doi:10.1155/2008/376805

Abstract

Mobile agent technology has emerged as a promising programming paradigm for developing highly dynamic and large-scale service-oriented computing middlewares due to its desirable features. For this purpose, first of all, scalable location-transparent agent communication issue should be addressed in mobile agent systems despite agent mobility. Although there were proposed several directory service and message delivery mechanisms, their disadvantages force them not to be appropriate to both low-overhead location management and fast delivery of messages to agents migrating frequently. To mitigate their limitations, this paper presents a scalable distributed directory service and message delivery mechanism. The proposed mechanism enables each mobile agent to autonomously leave tails of forwarding pointers on some few of its visiting nodes depending on its preferences. This feature results in low message forwarding overhead and low storage and maintenance cost of increasing chains of pointers per host. Also, keeping mobile agent location information in the effective binding cache of each sending agent, the sending agent can communicate with mobile agents much faster compared with the existing ones.

Highlights

Thanks to its desirable features such as asynchronous and dynamic execution and autonomy [12,17, 22,25], mobile agent technology has emerged as a promising programming paradigm for developing highly dynamic and large-scale service-oriented computing middlewares in various fields like ubiquitous computing [1,3,5,9,10,26], web service [28], grid computing [13,15] and adhoc network [19]
We attempt to develop our directory service and message delivery mechanism to have all three desirable features compared with the others as follows. + Alleviate the centralized dependency on the home node and its disconnection problem. + Require a small size of storage of each service node for agent location management. + Incur low message forwarding overhead
The mechanism P roposed reduces LInf ono by 79% compared with the mechanism Existing. These simulation results show that even if the scale of a mobile agent system grows considerably, our proposed mechanism P roposed incurs low message forwarding overhead and reduces the delivery time of each message destined to a mobile agent and the amount of agent location information kept by each service node compared with the previous one Existing

Summary

Introduction

Thanks to its desirable features such as asynchronous and dynamic execution and autonomy [12,17, 22,25], mobile agent technology has emerged as a promising programming paradigm for developing highly dynamic and large-scale service-oriented computing middlewares in various fields like ubiquitous computing [1,3,5,9,10,26], web service [28], grid computing [13,15] and adhoc network [19]. This mechanism is simple to implement and results in little mobile agent locating overhead It is unsuitable for highly mobile agents in distributed agent based systems because every agent location updating and message delivery are all performed around the home node, which introduces centralization. If a message is delivered to an agent not being at the home node, the message must traverse a list of forwarding nodes This mechanism can avoid performance bottlenecks of the global infrastructure, and improve its scalability, in large-scale distributed agent-based systems, compared with the home based one. In a previous work [16], a type of update message called inf orm message was introduced to include an agent’s current location for shortening the length of trails of forwarding pointers In this case, a node that receives the message is allowed to update its table if the received information is more recent than the one it had.

Mobile agent system model

Basic idea

Data structures and algorithms

Correctness

Experimental evaluation

Related work

Findings

Conclusion