Antecedence graph based checkpointing and recovery for mobile agents

Abstract

Mobile agents are distributed programs which can move autonomously in a network, to perform tasks on behalf of user. Though mobile agents offer much more flexibility as compared to client-server computing, yet they have additional cost and issues such as security, reliability and fault tolerance which need to be addressed for successful adaptability of mobile agent technology for developing real life applications. Fault tolerance aims to provide reliable execution of agents even in face of failures that may occur on account of various errors that emerge during migration request failure, communication exceptions, system crashes or security violations. The graph based fault tolerance protocols have been successfully used for the implementation of fault tolerance in distributed computing. This paper proposes use of antecedence graphs and message logs for maintaining fault tolerance information of mobile agents. In order to reduce the overheads of the carrying fault tolerance information in form of large antecedence graphs, we propose the use of parallel checkpointing algorithm. For checkpointing, dependent agents are marked out using antecedence graphs; and only these agents are involved in process of taking checkpoints. In case of failures, the antecedence graphs and message logs are regenerated for recovery and then normal operation continued. Analysis of results show considerable improvement in terms of reduced message overhead, execution and recovery times as compared to the graph based existing approach.