ABSTRACT

Mobile Agent technology has become a new paradigm for distributed real-time systems because of their inherent advantages. In any distributed system, along with other issues, survivability and fault tolerance are vital issues for deploying Mobile Agent for real applications. All Mobile Agent based applications face reliability problems due to the failure of agent platform, host and communication link etc. Mobile Agent technology has drawn attention of various researchers working in the area of distributed computing. Researchers have realized the benefits of using Mobile Agents over other existing technology and explore various area of application for Mobile Agents such as Electronic Commerce, Network Management, and Distributed Applications etc. However to fully deploy Mobile Agents in practice a number of challenging issues especially security, fault tolerance and privacy need to be addressed. The scope of this paper is limited to address fault tolerance problem of Mobile Agents in a multi agent environment. This paper identifies various faults in life cycle of Mobile Agent and proposes a comprehensive solution to tolerate all these faults. Paper also identifies the situations when Mobile Agent gets blocked and suggests several ways to avoid these blocks and continues its execution. Proposed solutions combine various existing fault tolerant mechanism to tolerate different kinds of faults. Proposed approach is hierarchical in nature, which combines both centralized and distributed approaches to take advantages of both. Thread base mechanism has been used to detect the failure of Mobile Agent and its executing environment. Heart-beat message passing and Ping command based techniques have been suggested to detect failure of Agent servers. Mobile agent system places have been introduced in this paper for Mobile agent execution. Modified itinerary options have also been explored for tolerating faults and to avoid blocking. Rear guard and acknowledgement based mechanism has been used to tolerate link failure and to ensure fault free migration of Mobile Agents across the networks.