A Hierarchical Navigation Map for A Fault-Tolerant Mobile Agent Model

Abstract

An application program on a faulty computer can be performed on another operational computer by moving the program in the mobile agent model. In this paper, we discuss a transactional agent (TA) model where a reliable and efficient application for manipulating objects in multiple computers is realized in the mobile agent model. Here, only a small part of the application program named routing (R) subagent moves around computers. A routing subagent autonomously finds a destination computer. We discuss a hierarchical navigation (HN) map which computer should be visited. A manipulating (M) subagent programs manipulating objects in a computer are loaded to the computer on arrival of R subagent in order to reduce the communication overhead. There are kinds of faulty computers for a transactional agent; current, destination, and sibling computers where a transactional agent now exists, will move, and has visited, respectively. The types of faults are detected by neighboring M subagents by communicating with each other. If some of the M subagents are faulty, the R subagent has to be aborted. However, the R subagent is still moving. We discuss how to efficiently deliver the abort message to the moving R subagent. We evaluate the TA model in terms of how long it takes to abort the R subagent if some computer is faulty.